We Keep Coding

Physical Device only - Google Maps - 'File.mkdir()' on a null object reference

I am running my code and getting this error when using app on mobile devide, but on emulator it is working.
E/AndroidRuntime: FATAL EXCEPTION: main
Process: com.example.nirbhaym.Indoor, PID: 17543
java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example.nirbhaym.Indoor/com.example.nirbhaym.indoor.MapsActivity}: android.view.InflateException: Binary XML file line #62: Error inflating class fragment
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2335)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2397)
at android.app.ActivityThread.access$800(ActivityThread.java:151)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1310)
at android.os.Handler.dispatchMessage(Handler.java:102)
at android.os.Looper.loop(Looper.java:135)
at android.app.ActivityThread.main(ActivityThread.java:5268)
at java.lang.reflect.Method.invoke(Native Method)
at java.lang.reflect.Method.invoke(Method.java:372)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:902)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:697)
Caused by: android.view.InflateException: Binary XML file line #62: Error inflating class fragment
at android.view.LayoutInflater.createViewFromTag(LayoutInflater.java:763)
at android.view.LayoutInflater.rInflate(LayoutInflater.java:806)
at android.view.LayoutInflater.inflate(LayoutInflater.java:504)
at android.view.LayoutInflater.inflate(LayoutInflater.java:414)
at android.view.LayoutInflater.inflate(LayoutInflater.java:365)
at android.support.v7.app.AppCompatDelegateImplV7.setContentView(AppCompatDelegateImplV7.java:256)
at android.support.v7.app.AppCompatActivity.setContentView(AppCompatActivity.java:109)
at com.example.nirbhaym.indoor.MapsActivity.onCreate(MapsActivity.java:50)
at android.app.Activity.performCreate(Activity.java:6033)
at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1106)
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2288)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2397) 
at android.app.ActivityThread.access$800(ActivityThread.java:151) 
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1310) 
at android.os.Handler.dispatchMessage(Handler.java:102) 
at android.os.Looper.loop(Looper.java:135) 
at android.app.ActivityThread.main(ActivityThread.java:5268) 
at java.lang.reflect.Method.invoke(Native Method) 
at java.lang.reflect.Method.invoke(Method.java:372) 
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:902) 
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:697) 
Caused by: java.lang.NullPointerException: Attempt to invoke virtual method 'boolean java.io.File.mkdir()' on a null object reference
at com.google.maps.api.android.lib6.gmm6.m.ad.a(Unknown Source)
at com.google.maps.api.android.lib6.gmm6.c.h.a(Unknown Source)
at com.google.maps.api.android.lib6.gmm6.c.y.a(Unknown Source)
at com.google.maps.api.android.lib6.e.bd.a(Unknown Source)
at com.google.maps.api.android.lib6.e.ev.a(Unknown Source)
at com.google.maps.api.android.lib6.e.z.a(Unknown Source)
at com.google.maps.api.android.lib6.e.y.a(Unknown Source)
at com.google.android.gms.maps.internal.u.onTransact(SourceFile:107)
at android.os.Binder.transact(Binder.java:380)
at com.google.android.gms.maps.internal.IMapFragmentDelegate$zza$zza.onCreateView(Unknown Source)
at com.google.android.gms.maps.SupportMapFragment$zza.onCreateView(Unknown Source)
at com.google.android.gms.dynamic.zza$4.zzb(Unknown Source)
at com.google.android.gms.dynamic.zza.zza(Unknown Source)
at com.google.android.gms.dynamic.zza.onCreateView(Unknown Source)
at com.google.android.gms.maps.SupportMapFragment.onCreateView(Unknown Source)
at android.support.v4.app.Fragment.performCreateView(Fragment.java:1962)
at android.support.v4.app.FragmentManagerImpl.moveToState(FragmentManager.java:1036)
at android.support.v4.app.FragmentManagerImpl.moveToState(FragmentManager.java:1226)
at android.support.v4.app.FragmentManagerImpl.addFragment(FragmentManager.java:1328)
at android.support.v4.app.FragmentManagerImpl.onCreateView(FragmentManager.java:2284)
at android.support.v4.app.FragmentController.onCreateView(FragmentController.java:111)
at android.support.v4.app.FragmentActivity.dispatchFragmentsOnCreateView(FragmentActivity.java:314)
at android.support.v4.app.BaseFragmentActivityHoneycomb.onCreateView(BaseFragmentActivityHoneycomb.java:31)
at android.support.v4.app.FragmentActivity.onCreateView(FragmentActivity.java:79)
at android.view.LayoutInflater.createViewFromTag(LayoutInflater.java:733)
at android.view.LayoutInflater.rInflate(LayoutInflater.java:806) 
at android.view.LayoutInflater.inflate(LayoutInflater.java:504) 
at android.view.LayoutInflater.inflate(LayoutInflater.java:414) 
at android.view.LayoutInflater.inflate(LayoutInflater.java:365) 
at android.support.v7.app.AppCompatDelegateImplV7.setContentView(AppCompatDelegateImplV7.java:256) 
at android.support.v7.app.AppCompatActivity.setContentView(AppCompatActivity.java:109) 
at com.example.nirbhaym.indoor.MapsActivity.onCreate(MapsActivity.java:50) 
at android.app.Activity.performCreate(Activity.java:6033) 
at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1106) 
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2288) 
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2397) 
at android.app.ActivityThread.access$800(ActivityThread.java:151) 
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1310) 
at android.os.Handler.dispatchMessage(Handler.java:102) 
at android.os.Looper.loop(Looper.java:135) 
at android.app.ActivityThread.main(ActivityThread.java:5268) 
at java.lang.reflect.Method.invoke(Native Method) 
at java.lang.reflect.Method.invoke(Method.java:372) 
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:902) 
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:697) 
I/Process: Sending signal. PID: 17543 SIG: 9
Application terminated.
Main activity code
package com.example.nirbhaym.indoor;
import com.google.android.gms.maps.CameraUpdateFactory;
import com.google.android.gms.maps.GoogleMap;
import com.google.android.gms.maps.OnMapReadyCallback;
import com.google.android.gms.maps.SupportMapFragment;
import com.google.android.gms.maps.model.BitmapDescriptor;
import com.google.android.gms.maps.model.BitmapDescriptorFactory;
import com.google.android.gms.maps.model.GroundOverlay;
import com.google.android.gms.maps.model.GroundOverlayOptions;
import com.google.android.gms.maps.model.LatLng;
import android.os.Bundle;
import android.support.v7.app.AppCompatActivity;
import android.view.View;
import android.widget.CheckBox;
import android.widget.SeekBar;
import android.widget.SeekBar.OnSeekBarChangeListener;
import java.util.ArrayList;
import java.util.List;
/**
* This shows how to add a ground overlay to a map.
*/
public class MapsActivity extends AppCompatActivity
implements OnSeekBarChangeListener, OnMapReadyCallback,
GoogleMap.OnGroundOverlayClickListener {
private static final int TRANSPARENCY_MAX = 100;
private static final LatLng NEWARK = new LatLng(28.544594, 77.272486);
private static final LatLng NEAR_NEWARK =
new LatLng(NEWARK.latitude - 0.001, NEWARK.longitude - 0.025);
private final List<BitmapDescriptor> mImages = new ArrayList<BitmapDescriptor>();
private GroundOverlay mGroundOverlay;
private GroundOverlay mGroundOverlayRotated;
private SeekBar mTransparencyBar;
private int mCurrentEntry = 0;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.layout);
mTransparencyBar = (SeekBar) findViewById(R.id.transparencySeekBar);
mTransparencyBar.setMax(TRANSPARENCY_MAX);
mTransparencyBar.setProgress(0);
SupportMapFragment mapFragment =
(SupportMapFragment) getSupportFragmentManager().findFragmentById(R.id.map);
mapFragment.getMapAsync(this);
}
#Override
public void onMapReady(GoogleMap map) {
// Register a listener to respond to clicks on GroundOverlays.
map.setOnGroundOverlayClickListener(this);
map.moveCamera(CameraUpdateFactory.newLatLngZoom(NEWARK, 11));
mImages.clear();
mImages.add(BitmapDescriptorFactory.fromResource(R.drawable.fourth_floor_app));
//mImages.add(BitmapDescriptorFactory.fromResource(R.drawable.newark_prudential_sunny));
// Add a small, rotated overlay that is clickable by default
// (set by the initial state of the checkbox.)
mGroundOverlayRotated = map.addGroundOverlay(new GroundOverlayOptions()
.image(mImages.get(0)).anchor(0, 1)
.position(NEAR_NEWARK, 4300f, 3025f)
.bearing(30)
.clickable(((CheckBox) findViewById(R.id.toggleClickability)).isChecked()));
// Add a large overlay at Newark on top of the smaller overlay.
mGroundOverlay = map.addGroundOverlay(new GroundOverlayOptions()
.image(mImages.get(mCurrentEntry)).anchor(0, 1)
.position(NEWARK, 8600f, 6500f));
mTransparencyBar.setOnSeekBarChangeListener(this);
// Override the default content description on the view, for accessibility mode.
// Ideally this string would be localised.
map.setContentDescription("Google Map with ground overlay.");
}
#Override
public void onStopTrackingTouch(SeekBar seekBar) {
}
#Override
public void onStartTrackingTouch(SeekBar seekBar) {
}
#Override
public void onProgressChanged(SeekBar seekBar, int progress, boolean fromUser) {
if (mGroundOverlay != null) {
mGroundOverlay.setTransparency((float) progress / (float) TRANSPARENCY_MAX);
}
}
public void switchImage(View view) {
mCurrentEntry = (mCurrentEntry + 1) % mImages.size();
mGroundOverlay.setImage(mImages.get(mCurrentEntry));
}
/**
* Toggles the visibility between 100% and 50% when a {#link GroundOverlay} is clicked.
*/
#Override
public void onGroundOverlayClick(GroundOverlay groundOverlay) {
// Toggle transparency value between 0.0f and 0.5f. Initial default value is 0.0f.
mGroundOverlayRotated.setTransparency(0.5f - mGroundOverlayRotated.getTransparency());
}
/**
* Toggles the clickability of the smaller, rotated overlay based on the state of the View that
* triggered this call.
* This callback is defined on the CheckBox in the layout for this Activity.
*/
public void toggleClickability(View view) {
if (mGroundOverlayRotated != null) {
mGroundOverlayRotated.setClickable(((CheckBox) view).isChecked());
}
}
}
Layout file
<?xml version="1.0" encoding="utf-8"?><!--
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical">
<RelativeLayout
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:background="#drawable/fourth_floor_app"
android:padding="5dp">
<TextView
android:id="#+id/transparency_text"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_gravity="center_vertical"
android:text="string/transparency" />
<SeekBar
android:id="#+id/transparencySeekBar"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:layout_toEndOf="#+id/transparency_text"
android:layout_toRightOf="#+id/transparency_text" />
<Button
android:id="#+id/switchImage"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_below="#+id/transparencySeekBar"
android:onClick="switchImage"
android:text="string/switch_image" />
<CheckBox
android:id="#+id/toggleClickability"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignBottom="#+id/switchImage"
android:layout_toEndOf="#+id/switchImage"
android:layout_toRightOf="#+id/switchImage"
android:checked="true"
android:onClick="toggleClickability"
android:text="string/clickable" />
</RelativeLayout>
<fragment
android:id="#+id/map"
class="com.google.android.gms.maps.SupportMapFragment"
android:layout_width="match_parent"
android:layout_height="match_parent" />
</LinearLayout>

FragmentManager fmanager = getSupportFragmentManager();
Fragment fragment = fmanager.findFragmentById(R.id.map);
SupportMapFragment supportmapfragment = (SupportMapFragment)fragment;
GoogleMap supportMap = supportmapfragment.getMap();
try this code. For this the tutorial is here hope this helps you. The problem is in fragment only. You need to check permissions also in above tutorial. Hope it helps you
http://www.truiton.com/2013/05/android-supportmapfragment-example/
EDIT:
Check permission for External Storage:
<uses-permission android:name="android.permission.READ_EXTERNAL_STORAGE" />
<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" />

Android - Trying to instantiate a class that is not a fragment

So I'm trying to create a fragment in my app that contains a toolbar (as an action bar) using appcompat activity so I can reuse it across multiple views.
I've tested a simple text-only fragment using a class that extends fragment only and got that to work, but to include a toolbar I need to extend AppCompatActivity in the view (I think).
When I try to get this to work, I get an error that says that my action_bar_fragment is not a Fragment.
I fell like I'm missing something basic here. Any ideas?
Main Activity:
package com.example.aaron.personaldataassistant;
import android.support.v7.app.ActionBar;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.content.Intent;
import android.support.v7.widget.Toolbar;
import android.view.MenuInflater;
import android.view.MenuItem;
import android.view.View;
import android.widget.Button;
import android.view.Menu;
import android.widget.Toast;
public class MainActivity extends AppCompatActivity {
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
// action_bar_fragment = (Toolbar) findViewById(R.id.action_bar_fragment);
// setSupportActionBar(action_bar_fragment);
}
#Override
public boolean onCreateOptionsMenu(Menu menu) {
MenuInflater mi=getMenuInflater();
mi.inflate(R.menu.action_bar, menu);
return super.onCreateOptionsMenu(menu);
}
Main Activity Layout:
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
xmlns:app="http://schemas.android.com/apk/res-auto"
android:orientation="vertical"
android:id="#+id/activity_main"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:paddingBottom="#dimen/activity_vertical_margin"
android:paddingLeft="#dimen/activity_horizontal_margin"
android:paddingRight="#dimen/activity_horizontal_margin"
android:paddingTop="#dimen/activity_vertical_margin"
tools:context="com.example.aaron.personaldataassistant.MainActivity">
<fragment
android:id="#+id/action_bar_fragment"
android:layout_width="wrap_content"
android:layout_height="match_parent"
class="com.example.aaron.personaldataassistant.action_bar_fragment"
tools:layout="#layout/action_bar_fragment" />
</LinearLayout>
Action Bar Fragment:
package com.example.aaron.personaldataassistant;
import android.os.Bundle;
import android.support.annotation.Nullable;
import android.support.v4.app.Fragment;
import android.support.v7.app.AppCompatActivity;
import android.support.v7.widget.Toolbar;
import android.view.LayoutInflater;
import android.view.Menu;
import android.view.MenuInflater;
import android.view.MenuItem;
import android.view.View;
import android.view.ViewGroup;
import android.widget.Toast;
public class action_bar_fragment extends AppCompatActivity {
public action_bar_fragment() {
}
Toolbar action_bar;
#Nullable
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
return inflater.inflate(R.layout.action_bar_fragment, container, false);
}
#Override
protected void onCreate (Bundle savedInstanceState){
super.onCreate(savedInstanceState);
setContentView(R.layout.action_bar_fragment);
action_bar = (Toolbar) findViewById(R.id.action_bar);
setSupportActionBar(action_bar);
}
#Override
public boolean onCreateOptionsMenu(Menu menu) {
MenuInflater mi = getMenuInflater();
mi.inflate(R.menu.action_bar, menu);
return super.onCreateOptionsMenu(menu);
}
#Override
public boolean onOptionsItemSelected(MenuItem item) {
int i = item.getItemId();
if (i == R.id.item1) {
Toast.makeText(action_bar_fragment.this, "Item 1", Toast.LENGTH_SHORT).show();
} else if (i == R.id.item2) {
Toast.makeText(action_bar_fragment.this, "Item 2", Toast.LENGTH_SHORT).show();
} else if (i == R.id.item3) {
Toast.makeText(action_bar_fragment.this, "Item 3", Toast.LENGTH_SHORT).show();
}
//replace toasts with desired actions: Settings, Help and Exit. Settigns is blank, help is context-dependent, exit gives possibility to exit
return super.onOptionsItemSelected(item);
}
}
Fragment Layout:
<FrameLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
xmlns:app="http://schemas.android.com/apk/res-auto"
tools:context="layout.Fragment_1">
<!-- TODO: Update blank fragment layout -->
<TextView
android:layout_width="match_parent"
android:layout_height="match_parent"
android:text="#string/hello_blank_fragment" />
<android.support.v7.widget.Toolbar
android:id="#+id/action_bar"
android:layout_width="300dp"
android:layout_height="?attr/actionBarSize"
android:background="?attr/colorPrimaryDark"
android:elevation="8dp"
android:theme="#style/ThemeOverlay.AppCompat.ActionBar"
app:popupTheme="#style/ThemeOverlay.AppCompat.Light"
android:layout_alignParentTop="true"
android:layout_alignParentLeft="true"
android:layout_alignParentStart="true"
/>
</FrameLayout>
And of course the error message:
--------- beginning of crash
E/AndroidRuntime: FATAL EXCEPTION: main
Process: com.example.aaron.personaldataassistant, PID: 2481
java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example.aaron.personaldataassistant/com.example.aaron.personaldataassistant.MainActivity}: android.view.InflateException: Binary XML file line #19: Binary XML file line #19: Error inflating class fragment
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2646)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2707)
at android.app.ActivityThread.-wrap12(ActivityThread.java)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1460)
at android.os.Handler.dispatchMessage(Handler.java:102)
at android.os.Looper.loop(Looper.java:154)
at android.app.ActivityThread.main(ActivityThread.java:6077)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:865)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:755)
Caused by: android.view.InflateException: Binary XML file line #19: Binary XML file line #19: Error inflating class fragment
Caused by: android.view.InflateException: Binary XML file line #19: Error inflating class fragment
Caused by: android.app.Fragment$InstantiationException: Trying to instantiate a class com.example.aaron.personaldataassistant.action_bar_fragment that is not a Fragment
at android.app.Fragment.instantiate(Fragment.java:617)
at android.app.Fragment.instantiate(Fragment.java:593)
at android.app.FragmentManagerImpl.onCreateView(FragmentManager.java:2302)
at android.app.FragmentController.onCreateView(FragmentController.java:98)
at android.app.Activity.onCreateView(Activity.java:5884)
at android.support.v4.app.BaseFragmentActivityHoneycomb.onCreateView(BaseFragmentActivityHoneycomb.java:36)
at android.support.v4.app.FragmentActivity.onCreateView(FragmentActivity.java:75)
at android.view.LayoutInflater.createViewFromTag(LayoutInflater.java:777)
at android.view.LayoutInflater.createViewFromTag(LayoutInflater.java:727)
at android.view.LayoutInflater.rInflate(LayoutInflater.java:858)
at android.view.LayoutInflater.rInflateChildren(LayoutInflater.java:821)
at android.view.LayoutInflater.inflate(LayoutInflater.java:518)
at android.view.LayoutInflater.inflate(LayoutInflater.java:426)
at android.view.LayoutInflater.inflate(LayoutInflater.java:377)
at android.support.v7.app.AppCompatDelegateImplV9.setContentView(AppCompatDelegateImplV9.java:284)
at android.support.v7.app.AppCompatActivity.setContentView(AppCompatActivity.java:140)
at com.example.aaron.personaldataassistant.MainActivity.onCreate(MainActivity.java:24)
at android.app.Activity.performCreate(Activity.java:6662)
at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1118)
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2599)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2707)
at android.app.ActivityThread.-wrap12(ActivityThread.java)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1460)
at android.os.Handler.dispatchMessage(Handler.java:102)
at android.os.Looper.loop(Looper.java:154)
at android.app.ActivityThread.main(ActivityThread.java:6077)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:865)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:755)
Caused by: java.lang.ClassCastException
at android.app.Fragment.instantiate(Fragment.java:618)
at android.app.Fragment.instantiate(Fragment.java:593) 
at android.app.FragmentManagerImpl.onCreateView(FragmentManager.java:2302) 
at android.app.FragmentController.onCreateView(FragmentController.java:98) 
at android.app.Activity.onCreateView(Activity.java:5884) 
at android.support.v4.app.BaseFragmentActivityHoneycomb.onCreateView(BaseFragmentActivityHoneycomb.java:36) 
at android.support.v4.app.FragmentActivity.onCreateView(FragmentActivity.java:75) 
at android.view.LayoutInflater.createViewFromTag(LayoutInflater.java:777) 
at android.view.LayoutInflater.createViewFromTag(LayoutInflater.java:727) 
at android.view.LayoutInflater.rInflate(LayoutInflater.java:858) 
at android.view.LayoutInflater.rInflateChildren(LayoutInflater.java:821) 
at android.view.LayoutInflater.inflate(LayoutInflater.java:518) 
at android.view.LayoutInflater.inflate(LayoutInflater.java:426) 
at android.view.LayoutInflater.inflate(LayoutInflater.java:377) 
at android.support.v7.app.AppCompatDelegateImplV9.setContentView(AppCompatDelegateImplV9.java:284) 
at android.support.v7.app.AppCompatActivity.setContentView(AppCompatActivity.java:140) 
at com.example.aaron.personaldataassistant.MainActivity.onCreate(MainActivity.java:24) 
at android.app.Activity.performCreate(Activity.java:6662) 
at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1118) 
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2599) 
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2707) 
at android.app.ActivityThread.-wrap12(ActivityThread.java) 
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1460) 
at android.os.Handler.dispatchMessage(Handler.java:102) 
at android.os.Looper.loop(Looper.java:154) 
at android.app.ActivityThread.main(ActivityThread.java:6077) 
at java.lang.reflect.Method.invoke(Native Method) 
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:865) 
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:755) 
Application terminated.
Thank you for your time.
UPDATE
This is great, the top answer helped me figure out that doing things in a fragment can require different methods than doing them in an Activity. Googling "How do I do X in a fragment" turned out to give me almost everything I needed. There is only one problem left now: I changed the Action Bar Fragment line 37 to
setHasOptionsMenu(true);
action_bar = (Toolbar) getView().findViewById(R.id.action_bar);
This is giving me a null object reference, but the layout definitely exists! Any idea what's going on?
The relevant part of the error message is:
Caused by: java.lang.NullPointerException: Attempt to invoke virtual method 'android.view.View android.view.View.findViewById(int)' on a null object reference
Sorry for the long delay getting back to you, I had work. Should be faster this time!
I will also clean up the comment I made on your reply.

This is because your intended fragment is not a Fragment but an Activity, where:
action_bar_fragment extends AppCompatActivity {
}
is an Activity, so you should be extends action_bar_fragment with Fragment:
action_bar_fragment extends Fragment {
}
And please change your code style, where action_bar_fragment should be something like ActionBarFragment. A class name should be started with uppercase.
Please read Creating and Using Fragments.

I came upon this question because of the main title "Trying to instantiate a class that is not a Fragment". So maybe my solution can help. I'm using Android Studio 2.2.3 and targeting API 15.
I got that error:
...
Caused by: android.app.Fragment$InstantiationException: Trying to instantiate a class com.xyz.tuv.MyFragment that is not a Fragment
because I was importing:
import android.support.v4.app.Fragment;
instead of
import android.app.Fragment;
Since API 11, you can use a regular activity (android.app.Activity) for inserting fragments as documented here. But in that case you also have to use android.app.Fragment, contrary to what the main example shows.

In your MainActivity class, you have to change the order of some of code, they are:
#Override
public boolean onCreateOptionsMenu(Menu menu) {
MenuInflater mi=getMenuInflater();
mi.inflate(R.menu.action_bar, menu);
return super.onCreateOptionsMenu(menu);
}
Change it to :
#Override
public boolean onCreateOptionsMenu(Menu menu) {
super.onCreateOptionsMenu(menu);
MenuInflater mi = getMenuInflater();
mi.inflate(R.menu.action_bar, menu);
return true;
}
and try again.

TabHost addTabs on Android crashes the apk

I have a problem that I can not solve, the problem TabHost that crashes when apk run,I've been trying hard for this but still can not, please help.
activity_main.xml
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools" android:layout_width="match_parent"
android:layout_height="match_parent" android:paddingLeft="#dimen/activity_horizontal_margin"
android:paddingRight="#dimen/activity_horizontal_margin"
android:paddingTop="#dimen/activity_vertical_margin"
android:paddingBottom="#dimen/activity_vertical_margin" tools:context=".MainActivity">
<TabHost
android:id="#android:id/tabhost"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:layout_alignParentTop="true"
android:layout_centerHorizontal="true">
<LinearLayout
android:layout_width="fill_parent"
android:layout_height="fill_parent"
android:orientation="vertical">
<TabWidget
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:id="#android:id/tabs"
android:layout_gravity="bottom"></TabWidget>
<FrameLayout
android:layout_width="fill_parent"
android:layout_height="fill_parent"
android:layout_gravity="bottom"
android:id="#android:id/tabcontent"></FrameLayout>
</LinearLayout>
</TabHost>
</RelativeLayout>
MainActivity.java
package com.example.asus.smartcity;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.Menu;
import android.view.MenuItem;
import android.content.Intent;
import android.widget.TabHost;
public class MainActivity extends AppCompatActivity {
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
TabHost tabhostku = (TabHost)findViewById(android.R.id.tabhost);
tabhostku.setup();
TabHost.TabSpec spec;
Intent intent;
intent = new Intent().setClass(this, MapActivity.class);
spec = tabhostku.newTabSpec("map");
spec.setIndicator("map",null);
spec.setContent(intent);
tabhostku.addTab(spec);
intent = new Intent().setClass(this, PlaceActivity.class);
spec = tabhostku.newTabSpec("place");
spec.setIndicator("place",null);
spec.setContent(intent);
tabhostku.addTab(spec);
}
#Override
public boolean onCreateOptionsMenu(Menu menu) {
// Inflate the menu; this adds items to the action bar if it is present.
getMenuInflater().inflate(R.menu.menu_main, menu);
return true;
}
#Override
public boolean onOptionsItemSelected(MenuItem item) {
// Handle action bar item clicks here. The action bar will
// automatically handle clicks on the Home/Up button, so long
// as you specify a parent activity in AndroidManifest.xml.
int id = item.getItemId();
//noinspection SimplifiableIfStatement
if (id == R.id.action_settings) {
return true;
}
return super.onOptionsItemSelected(item);
}
}
MapActivity.java
import android.app.Activity;
import android.os.Bundle;
/**
* Created by Asus on 11-Nov-15.
*/
public class MapActivity extends Activity{
public void onCreate(Bundle savedInstanceState){
super.onCreate(savedInstanceState);
setContentView(R.layout.map);
}
}
PlaceActivity.java
package com.example.asus.smartcity;
import android.os.Bundle;
import android.app.ListActivity;
import android.widget.ArrayAdapter;
/**
* Created by Asus on 11-Nov-15.
*/
public class PlaceActivity extends ListActivity {
String []placeku={"KBS","Surabaya Carnival","Kebun Bibit"};
public void onCreate(Bundle savedInstanceState){
super.onCreate(savedInstanceState);
setContentView(R.layout.place);
setListAdapter(new ArrayAdapter<String>(this, android.R.layout.simple_expandable_list_item_1,placeku));
}
}
Logcat
11-11 12:51:22.153 19591-19591/? I/art﹕ Late-enabling -Xcheck:jni
11-11 12:51:22.223 19591-19591/com.example.asus.smartcity W/ResourceType﹕ For resource 0x01040529, entry index(1321) is beyond type entryCount(1)
11-11 12:51:22.287 19591-19591/com.example.asus.smartcity W/ResourceType﹕ For resource 0x0104007b, entry index(123) is beyond type entryCount(1)
11-11 12:51:22.288 19591-19591/com.example.asus.smartcity W/ResourceType﹕ For resource 0x01040077, entry index(119) is beyond type entryCount(1)
11-11 12:51:22.314 19591-19591/com.example.asus.smartcity W/ResourceType﹕ For resource 0x0104007b, entry index(123) is beyond type entryCount(1)
11-11 12:51:22.318 19591-19591/com.example.asus.smartcity D/AndroidRuntime﹕ Shutting down VM
11-11 12:51:22.320 19591-19591/com.example.asus.smartcity E/AndroidRuntime﹕ FATAL EXCEPTION: main
Process: com.example.asus.smartcity, PID: 19591
java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example.asus.smartcity/com.example.asus.smartcity.MainActivity}: java.lang.IllegalStateException: Did you forget to call 'public void setup(LocalActivityManager activityGroup)'?
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2379)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2442)
at android.app.ActivityThread.access$800(ActivityThread.java:156)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1351)
at android.os.Handler.dispatchMessage(Handler.java:102)
at android.os.Looper.loop(Looper.java:211)
at android.app.ActivityThread.main(ActivityThread.java:5371)
at java.lang.reflect.Method.invoke(Native Method)
at java.lang.reflect.Method.invoke(Method.java:372)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:945)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:740)
Caused by: java.lang.IllegalStateException: Did you forget to call 'public void setup(LocalActivityManager activityGroup)'?
at android.widget.TabHost$IntentContentStrategy.getContentView(TabHost.java:754)
at android.widget.TabHost.setCurrentTab(TabHost.java:420)
at android.widget.TabHost.addTab(TabHost.java:247)
at com.example.asus.smartcity.MainActivity.onCreate(MainActivity.java:29)
at android.app.Activity.performCreate(Activity.java:5990)
at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1106)
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2332)
            at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2442)
            at android.app.ActivityThread.access$800(ActivityThread.java:156)
            at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1351)
            at android.os.Handler.dispatchMessage(Handler.java:102)
            at android.os.Looper.loop(Looper.java:211)
            at android.app.ActivityThread.main(ActivityThread.java:5371)
            at java.lang.reflect.Method.invoke(Native Method)
            at java.lang.reflect.Method.invoke(Method.java:372)
            at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:945)
            at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:740)
11-11 12:51:25.717 19591-19591/com.example.asus.smartcity I/Process﹕ Sending signal. PID: 19591 SIG: 9

You have to change extends AppCompatActivity to ActivityGroup After that change
tabhostku.setup();
to
tabhostku.setup(this.getLocalActivityManager());

Try this,
Change,
tabhostku.setup();
to
mlam = new LocalActivityManager(this, false);
tabhostku.setup(mlam );
And in onPause and onResume add the following code.
#Override
public void onPause() {
super.onPause();
try {
mlam.dispatchPause(isFinishing());
} catch (Exception e) {}
}
#Override
public void onResume() {
super.onResume();
try {
mlam.dispatchResume();
} catch (Exception e) {}
}

Android bug - Binary XML file line #1: Error inflating class fragment

I am attempting to implement a to-do list using listview and listview adapter but have run into several runtime exceptions that I can't overcome. Logcat says that I am trying to invoke findViewById on a null object reference (line 24 = private Spinner spinner_priority;). However, the id for the spinner is spinnerPriority and findViewById(R.id.spinnerPriority) is invoked correctly.
I haven't changed the default ToDoActivity.java implementation except for extending ToDoActivity from FragmentActivity instead of AppCombatActivity and importing android.support.v4.app.FragmentActivity instead of android.app.FragmentActivity.
Any insights as to why the app is crashing?
Logcat:
08-27 00:45:58.209 11873-11873/? E/AndroidRuntime﹕ FATAL EXCEPTION: main
Process: com.ttse.final_tse, PID: 11873
java.lang.RuntimeException: Unable to start activity ComponentInfo{com.ttse.final_tse/com.ttse.final_tse.ToDoActivity}: android.view.InflateException: Binary XML file line #1: Error inflating class fragment
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2325)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2387)
at android.app.ActivityThread.access$800(ActivityThread.java:151)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1303)
at android.os.Handler.dispatchMessage(Handler.java:102)
at android.os.Looper.loop(Looper.java:135)
at android.app.ActivityThread.main(ActivityThread.java:5254)
at java.lang.reflect.Method.invoke(Native Method)
at java.lang.reflect.Method.invoke(Method.java:372)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:903)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:698)
Caused by: android.view.InflateException: Binary XML file line #1: Error inflating class fragment
at android.view.LayoutInflater.createViewFromTag(LayoutInflater.java:763)
at android.view.LayoutInflater.inflate(LayoutInflater.java:482)
at android.view.LayoutInflater.inflate(LayoutInflater.java:414)
at android.view.LayoutInflater.inflate(LayoutInflater.java:365)
at com.android.internal.policy.impl.PhoneWindow.setContentView(PhoneWindow.java:378)
at android.app.Activity.setContentView(Activity.java:2145)
at com.ttse.final_tse.ToDoActivity.onCreate(ToDoActivity.java:14)
at android.app.Activity.performCreate(Activity.java:5990)
at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1106)
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2278)
            at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2387)
            at android.app.ActivityThread.access$800(ActivityThread.java:151)
            at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1303)
            at android.os.Handler.dispatchMessage(Handler.java:102)
            at android.os.Looper.loop(Looper.java:135)
            at android.app.ActivityThread.main(ActivityThread.java:5254)
            at java.lang.reflect.Method.invoke(Native Method)
            at java.lang.reflect.Method.invoke(Method.java:372)
            at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:903)
            at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:698)
Caused by: java.lang.NullPointerException: Attempt to invoke virtual method 'android.view.View android.support.v4.app.FragmentActivity.findViewById(int)' on a null object reference
at com.ttse.final_tse.ToDoActivityFragment.<init>(ToDoActivityFragment.java:24)
at java.lang.reflect.Constructor.newInstance(Native Method)
at java.lang.Class.newInstance(Class.java:1606)
at android.support.v4.app.Fragment.instantiate(Fragment.java:421)
at android.support.v4.app.Fragment.instantiate(Fragment.java:396)
at android.support.v4.app.FragmentManagerImpl.onCreateView(FragmentManager.java:2162)
at android.support.v4.app.FragmentActivity.onCreateView(FragmentActivity.java:300)
at android.view.LayoutInflater.createViewFromTag(LayoutInflater.java:727)
            at android.view.LayoutInflater.inflate(LayoutInflater.java:482)
            at android.view.LayoutInflater.inflate(LayoutInflater.java:414)
            at android.view.LayoutInflater.inflate(LayoutInflater.java:365)
            at com.android.internal.policy.impl.PhoneWindow.setContentView(PhoneWindow.java:378)
            at android.app.Activity.setContentView(Activity.java:2145)
            at com.ttse.final_tse.ToDoActivity.onCreate(ToDoActivity.java:14)
            at android.app.Activity.performCreate(Activity.java:5990)
            at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1106)
            at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2278)
            at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2387)
            at android.app.ActivityThread.access$800(ActivityThread.java:151)
            at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1303)
            at android.os.Handler.dispatchMessage(Handler.java:102)
            at android.os.Looper.loop(Looper.java:135)
            at android.app.ActivityThread.main(ActivityThread.java:5254)
            at java.lang.reflect.Method.invoke(Native Method)
            at java.lang.reflect.Method.invoke(Method.java:372)
            at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:903)
            at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:698)
ToDoActivity.java
package com.ttse.final_tse;
import android.support.v4.app.FragmentActivity;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.Menu;
import android.view.MenuItem;
public class ToDoActivity extends FragmentActivity {
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_to_do);
}
#Override
public boolean onCreateOptionsMenu(Menu menu) {
// Inflate the menu; this adds items to the action bar if it is present.
getMenuInflater().inflate(R.menu.menu_to_do, menu);
return true;
}
#Override
public boolean onOptionsItemSelected(MenuItem item) {
// Handle action bar item clicks here. The action bar will
// automatically handle clicks on the Home/Up button, so long
// as you specify a parent activity in AndroidManifest.xml.
int id = item.getItemId();
//noinspection SimplifiableIfStatement
if (id == R.id.action_settings) {
return true;
}
return super.onOptionsItemSelected(item);
}
}
activity_to_do.xml
<fragment xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:id="#+id/fragment"
android:name="com.ttse.final_tse.ToDoActivityFragment"
tools:layout="#layout/fragment_to_do"
android:layout_width="match_parent"
android:layout_height="match_parent"/>
ToDoActivityFragment.java
package com.ttse.final_tse;
import android.app.DialogFragment;
import android.support.v4.app.Fragment;
import android.os.Bundle;
import android.text.TextUtils;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.AdapterView;
import android.widget.ArrayAdapter;
import android.widget.Button;
import android.widget.EditText;
import android.widget.ListView;
import android.widget.Spinner;
import android.widget.TextView;
import android.widget.Toast;
import java.util.ArrayList;
import java.util.List;
public class ToDoActivityFragment extends Fragment {
private List<Task> list_tasks = new ArrayList<Task>();
private ArrayAdapter<Task> list_adapter = null;
private final EditText editText_title = (EditText)getActivity().findViewById(R.id.editTextTitle);
private Spinner spinner_priority;
private Button button_datepicker;
private final TextView textView_date = (TextView)getActivity().findViewById(R.id.textViewDate);
private EditText editText_shortDescr;
private Button button_save;
public ToDoActivityFragment() {
}
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
return inflater.inflate(R.layout.fragment_to_do, container, false);
}
#Override
public void onActivityCreated(Bundle savedInstanceState) {
super.onActivityCreated(savedInstanceState);
// To-Do ListView
ListView list = (ListView)getActivity().findViewById(R.id.listViewToDo);
list_adapter = new ArrayAdapter<Task>(getActivity(), android.R.layout.simple_list_item_1, list_tasks);
list.setAdapter(list_adapter);
// Priority Spinner
spinner_priority = (Spinner)getActivity().findViewById(R.id.spinnerPriority);
ArrayAdapter<CharSequence> spinner_adapter = ArrayAdapter.createFromResource(getActivity(), R.array.priority_array, android.R.layout.simple_spinner_item);
spinner_adapter.setDropDownViewResource(android.R.layout.simple_spinner_dropdown_item);
spinner_priority.setAdapter(spinner_adapter);
spinner_priority.setOnItemSelectedListener(new AdapterView.OnItemSelectedListener() {
#Override
public void onItemSelected(AdapterView<?> parent, View view, int position, long id) {
}
#Override
public void onNothingSelected(AdapterView<?> parent) {
}
});
// Datepicker Button
button_datepicker = (Button)getActivity().findViewById(R.id.buttonDatepicker);
button_datepicker.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
showDatePickerDialog(v);
}
});
// Short Description EditText
editText_shortDescr = (EditText)getActivity().findViewById(R.id.editTextShortDescr);
// Save Button
button_save = (Button)getActivity().findViewById(R.id.buttonSave);
button_save.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
if(TextUtils.isEmpty(editText_title.getText()) || TextUtils.isEmpty(textView_date.getText())) {
Toast.makeText(getActivity(), "Please set to-do title and due date", Toast.LENGTH_SHORT).show();
return;
}
onSave();
}
});
}
private void showDatePickerDialog(View v) {
DialogFragment date_picker = new DatePickerFragment();
// show datepicker fragment on screen
date_picker.show(getActivity().getFragmentManager(), "datePicker");
}
private void onSave() {
Task task = new Task();
task.setTitle(editText_title.getText().toString());
task.setPriority(spinner_priority.getSelectedItem().toString());
task.setDueDate(textView_date.getText().toString());
task.setShortDescr(editText_shortDescr.getText().toString());
list_adapter.add(task);
list_adapter.notifyDataSetChanged();
}
}
fragment_to_do.xml
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:orientation="vertical"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:paddingLeft="#dimen/activity_horizontal_margin"
android:paddingRight="#dimen/activity_horizontal_margin"
android:paddingTop="#dimen/activity_vertical_margin"
android:paddingBottom="#dimen/activity_vertical_margin"
tools:context=".ToDoActivityFragment">
<ListView
android:id="#+id/listViewToDo"
android:layout_width="match_parent"
android:layout_height="0dp"
android:layout_weight="10">
</ListView>
<LinearLayout
android:layout_width="match_parent"
android:layout_height="0dp"
android:orientation="vertical"
android:layout_weight="7">
<EditText
android:id="#+id/editTextTitle"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:hint="Title..."/>
<LinearLayout
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:orientation="horizontal">
<TextView
android:layout_width="0dp"
android:layout_height="wrap_content"
android:layout_weight="3"
android:text="Priority Level:"
android:layout_marginTop="5dp"/>
<Spinner
android:id="#+id/spinnerPriority"
android:layout_width="0dp"
android:layout_height="wrap_content"
android:layout_weight="4"
android:spinnerMode="dropdown"
android:layout_marginTop="5dp"/>
<LinearLayout
android:layout_width="0dp"
android:layout_height="wrap_content"
android:layout_weight="4"
android:orientation="vertical">
<Button
android:id="#+id/buttonDatepicker"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_gravity="center"
android:text="#string/pick_date"/>
<TextView
android:id="#+id/textViewDate"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_gravity="center"/>
</LinearLayout>
</LinearLayout>
<EditText
android:id="#+id/editTextShortDescr"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:hint="Short description..."
android:textSize="14sp"/>
<Button
android:id="#+id/buttonSave"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="#string/text_save"
android:layout_gravity="center"/>
</LinearLayout>
</LinearLayout>
DatePickerFragment.java
package com.ttse.final_tse;
import android.app.DatePickerDialog;
import android.app.Dialog;
import android.app.DialogFragment;
import android.os.Bundle;
import android.widget.DatePicker;
import android.widget.TextView;
import java.util.Calendar;
public class DatePickerFragment extends DialogFragment
implements DatePickerDialog.OnDateSetListener {
#Override
public Dialog onCreateDialog(Bundle savedInstanceState) {
final Calendar c = Calendar.getInstance();
int year = c.get(Calendar.YEAR);
int month = c.get(Calendar.MONTH);
int day = c.get(Calendar.DAY_OF_MONTH);
return new DatePickerDialog(getActivity(), this, year, month, day);
}
public void onDateSet(DatePicker view, int year, int month, int day) {
TextView textView_date = (TextView)getActivity().findViewById(R.id.textViewDate);
textView_date.setText(new StringBuilder()
.append(month + 1).append("/").append(day).append("/")
.append(year));
}
}
Task.java
package com.ttse.final_tse;
public class Task {
private String mTitle;
private String mDueDate;
private String mPriority;
private String mShortDescr;
public String getTitle() {
return mTitle;
}
public void setTitle(String title) {
mTitle = title;
}
public String getDueDate() {
return mDueDate;
}
public void setDueDate(String dueDate) {
mDueDate = dueDate;
}
public String getPriority() {
return mPriority;
}
public void setPriority(String priority) {
mPriority = priority;
}
public String getShortDescr() {
return mShortDescr;
}
public void setShortDescr(String shortDescr) {
mShortDescr = shortDescr;
}
}

update your code like this
private EditText editText_title ;
private TextView textView_date ;
initialize in onActivityCreated
#Override
public void onActivityCreated(Bundle savedInstanceState) {
super.onActivityCreated(savedInstanceState);
// To-Do ListView
editText_title = (EditText)getActivity().findViewById(R.id.editTextTitle);
textView_date = (TextView)getActivity().findViewById(R.id.textViewDate);

Android - How to access a Fragment from a FragmentActivity

I always get a NullPointerException when I try to access a fragment from inside my main activity. No matter what I do.
The issue is that I use TabsPagerAdapter and ViewPager and I don't know how to get the inflated views (the fragment's onCreate() method returns the inflated view already).
The goal is to get access to an element inside the fragment and hide or show it dynamically by a single background thread which should also do this for more fragments.
MainActivity.java
public class MainActivity extends FragmentActivity implements
ActionBar.TabListener
{
/* swipe view */
private ViewPager viewPager;
private TabsPagerAdapter mAdapter;
private android.app.ActionBar actionBar;
// tab titles
private String[] tabs = { "Basic", "Advanced", "Settings"};
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
/* init swipe views */
mAdapter = new TabsPagerAdapter(getSupportFragmentManager());
viewPager = (ViewPager) findViewById(R.id.pager);
viewPager.setAdapter(mAdapter);
actionBar = getActionBar();
actionBar.setHomeButtonEnabled(false);
actionBar.setNavigationMode(ActionBar.NAVIGATION_MODE_TABS);
/* addTab returns void, how to geht my fragements and their views???*/
for (String tabName : tabs)
actionBar.addTab(actionBar.newTab().setText(tabName).setTabListener(this));
viewPager.setOnPageChangeListener(new ViewPager.OnPageChangeListener() {
#Override
public void onPageSelected(int position) {
actionBar.setSelectedNavigationItem(position);
}
#Override
public void onPageScrolled(int arg0, float arg1, int arg2) {}
#Override
public void onPageScrollStateChanged(int arg0) {}
});
}
public void testFunction()
{
FragmentPage1 fragmentPage1 = (FragmentPage1) getSupportFragmentManager().findFragmentById(R.layout.fragment_page1);
GridLayout gridlayout = (GridLayout) fragmentPage1.getRootView().findViewById(R.id.adBannerBasicLayout);
gridlayout.setVisibility(GridLayout.VISIBLE); /* THATS MY GOAL */
}
FragmentPage1.java
public class FragmentPage1 extends Fragment {
private View rootView;
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
rootView = inflater.inflate(R.layout.fragment_page1, container, false);
/* HERE IT IS WORKING FINE,
but later I want to make it visible again
from code OUTSIDE FragmentPage1 ??? */
GridLayout gridlayout = (GridLayout) rootView.findViewById(R.id.adBannerBasicLayout);
gridlayout.setVisibility(GridLayout.GONE);
return rootView;
}
/* so I tried this, but also get always NullPointerException */
public View getRootView()
{
return rootView;
}
}
fragment_page1.xml
<?xml version="1.0" encoding="utf-8"?>
<ScrollView
xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:ads="http://schemas.android.com/apk/res-auto"
android:id="#+id/settings_scroll_view"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
>
<GridLayout
xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:ads="http://schemas.android.com/apk/res-auto"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:background="#000000"
android:orientation="vertical"
android:rowCount="12"
android:columnCount="5"
>
<!-- Some Banner Ads I want to hide show -->
<!-- I want to access this from everywhere! -->
<GridLayout
xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:ads="http://schemas.android.com/apk/res-auto"
android:id="#+id/adBannerBasicLayout"
android:orientation="vertical"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_gravity="fill"
android:rowCount="3"
android:columnCount="1"
android:layout_row="0"
android:layout_column="0"
android:layout_columnSpan="5">
<Space
android:layout_width="0dp"
android:layout_height="5dp"
android:layout_row="0"
android:layout_column="0"
/>
<com.google.android.gms.ads.AdView
android:id="#+id/adBannerBasic"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_gravity="fill"
ads:adSize="BANNER"
ads:adUnitId="xxxxxxxxxxxxxxxxxxxxxxxxxx"
android:layout_row="1"
android:layout_column="0"
>
</com.google.android.gms.ads.AdView>
<Space
android:layout_width="0dp"
android:layout_height="5dp"
android:layout_row="2"
android:layout_column="0"
/>
</GridLayout>
<!-- more stuff... -->
</GridLayout>
</ScrollView>
Please help me out, I'm totally stuck!
THANKS!
EDIT:
The scond line in testFunction() throws the NullPointerException:
GridLayout gridlayout = (GridLayout) fragmentPage1.getRootView().findViewById(R.id.adBannerBasicLayout);
because getSupportFragmentManager() always returns null:
FragmentPage1 fragmentPage1 = (FragmentPage1) getSupportFragmentManager().findFragmentById(R.layout.fragment_page1);
Logcat Outoput
java.lang.IllegalStateException: Could not execute method of the activity
at android.view.View$1.onClick(View.java:3969)
at android.view.View.performClick(View.java:4633)
at android.view.View$PerformClick.run(View.java:19330)
at android.os.Handler.handleCallback(Handler.java:733)
at android.os.Handler.dispatchMessage(Handler.java:95)
at android.os.Looper.loop(Looper.java:157)
at android.app.ActivityThread.main(ActivityThread.java:5356)
at java.lang.reflect.Method.invokeNative(Native Method)
at java.lang.reflect.Method.invoke(Method.java:515)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1265)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:1081)
at de.robv.android.xposed.XposedBridge.main(XposedBridge.java:132)
at dalvik.system.NativeStart.main(Native Method)
Caused by: java.lang.reflect.InvocationTargetException
at java.lang.reflect.Method.invokeNative(Native Method)
at java.lang.reflect.Method.invoke(Method.java:515)
at android.view.View$1.onClick(View.java:3964)
            at android.view.View.performClick(View.java:4633)
            at android.view.View$PerformClick.run(View.java:19330)
            at android.os.Handler.handleCallback(Handler.java:733)
            at android.os.Handler.dispatchMessage(Handler.java:95)
            at android.os.Looper.loop(Looper.java:157)
            at android.app.ActivityThread.main(ActivityThread.java:5356)
            at java.lang.reflect.Method.invokeNative(Native Method)
            at java.lang.reflect.Method.invoke(Method.java:515)
            at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1265)
            at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:1081)
            at de.robv.android.xposed.XposedBridge.main(XposedBridge.java:132)
            at dalvik.system.NativeStart.main(Native Method)
Caused by: java.lang.NullPointerException
at org.tzapp.smote.MainActivity.testFuntion(MainActivity.java:393)
            at java.lang.reflect.Method.invokeNative(Native Method)
            at java.lang.reflect.Method.invoke(Method.java:515)
            at android.view.View$1.onClick(View.java:3964)
            at android.view.View.performClick(View.java:4633)
            at android.view.View$PerformClick.run(View.java:19330)
            at android.os.Handler.handleCallback(Handler.java:733)
            at android.os.Handler.dispatchMessage(Handler.java:95)
            at android.os.Looper.loop(Looper.java:157)
            at android.app.ActivityThread.main(ActivityThread.java:5356)
            at java.lang.reflect.Method.invokeNative(Native Method)
            at java.lang.reflect.Method.invoke(Method.java:515)
            at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1265)
            at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:1081)
            at de.robv.android.xposed.XposedBridge.main(XposedBridge.java:132)
            at dalvik.system.NativeStart.main(Native Method)

You are using the wrong static value from the auto generated R file!
Instead of using R.layout.fragment_page1 which references the XML resource you should use R.id.fragment_page1 which should be the id of the fragment in your R.layout.activity_main XML file at /res/layout/activity_main.xml
R.layout references XML layout files
R.id references individual XML nodes (Views, Fragments etc.)
So in short, change:
FragmentPage1 fragmentPage1 = (FragmentPage1) getSupportFragmentManager().findFragmentById(R.layout.fragment_page1);
To:
FragmentPage1 fragmentPage1 = (FragmentPage1) getSupportFragmentManager().findFragmentById(R.id.fragment_page1);
And make sure that your fragment id in /res/layout/activity_main.xml is set to R.id.fragment_page1 like so:
<fragment android:name="com.example.yourpackage.FragmentPage1"
android:id="#+id/fragment_page1"
android:layout_weight="1"
android:layout_width="0dp"
android:layout_height="match_parent" />

you use getSupportFragmentManager() to get fragment.
Please double check if your FragmentPage1 extends a android.support.v4.app.Fragment;
not a
android.Fragment;

After updating SDK and repository, there is new trouble. I cant build anymore and I dont want to compile on level 23 :(
Information:Gradle tasks [clean, :app:generateDebugSources, :app:generateDebugTestSources]
:app:clean
:app:preBuild
:app:preDebugBuild
:app:checkDebugManifest
:app:preReleaseBuild
:app:prepareComAndroidSupportAppcompatV72300Library
:app:prepareComAndroidSupportSupportV42300Library
:app:prepareComGoogleAndroidGmsPlayServicesAds750Library
:app:prepareComGoogleAndroidGmsPlayServicesAnalytics750Library
:app:prepareComGoogleAndroidGmsPlayServicesBase750Library
:app:prepareComInstabugLibraryInstabugcore161Library
:app:prepareComInstabugLibraryInstabugsupport161Library
:app:prepareDebugDependencies
:app:compileDebugAidl
:app:compileDebugRenderscript
:app:generateDebugBuildConfig
:app:generateDebugAssets UP-TO-DATE
:app:mergeDebugAssets
:app:generateDebugResValues UP-TO-DATE
:app:generateDebugResources
:app:mergeDebugResources
:app:processDebugManifest
:app:processDebugResources
C:\Users\Tom\AndroidStudioProjects\SSMote\app\build\intermediates\exploded-aar\com.android.support\appcompat-v7\23.0.0\res\values-v23\values-v23.xml
Error:(1) Error retrieving parent for item: No resource found that matches the given name 'android:TextAppearance.Material.Widget.Button.Inverse'.
Error:(1) Error retrieving parent for item: No resource found that matches the given name 'android:Widget.Material.Button.Colored'.
Error:Execution failed for task ':app:processDebugResources'.
> com.android.ide.common.internal.LoggedErrorException: Failed to run command:
C:\Users\Tom\AppData\Local\Android\sdk\build-tools\21.1.2\aapt.exe package -f --no-crunch -I C:\Users\Tom\AppData\Local\Android\sdk\platforms\android-21\android.jar -M C:\Users\Tom\AndroidStudioProjects\SSMote\app\build\intermediates\manifests\full\debug\AndroidManifest.xml -S C:\Users\Tom\AndroidStudioProjects\SSMote\app\build\intermediates\res\debug -A C:\Users\Tom\AndroidStudioProjects\SSMote\app\build\intermediates\assets\debug -m -J C:\Users\Tom\AndroidStudioProjects\SSMote\app\build\generated\source\r\debug -F C:\Users\Tom\AndroidStudioProjects\SSMote\app\build\intermediates\res\resources-debug.ap_ --debug-mode --custom-package org.tzapp.smote -0 apk --output-text-symbols C:\Users\Tom\AndroidStudioProjects\SSMote\app\build\intermediates\symbols\debug
Error Code:
1
Output:
C:\Users\Tom\AndroidStudioProjects\SSMote\app\build\intermediates\res\debug\values-v23\values.xml:5: error: Error retrieving parent for item: No resource found that matches the given name 'android:TextAppearance.Material.Widget.Button.Inverse'.
C:\Users\Tom\AndroidStudioProjects\SSMote\app\build\intermediates\res\debug\values-v23\values.xml:20: error: Error retrieving parent for item: No resource found that matches the given name 'android:Widget.Material.Button.Colored'.
Information:BUILD FAILED
Information:Total time: 40.157 secs
Information:3 errors
Information:0 warnings

Also I found another answer, which is I think most satisfying :)
I forgot to mention that there is another class. It all comes from that stupid piece of example code for Swipe Views which is avaible somewhere on developers.google.com ...
Everytime I tried to access the FragmentPages via my TabPagerAdapter class using the stupid getItem(int i) method, I created a new Fragment() :-/ Very irritating!
Class TabsPagerAdapter from bad google example
public class TabsPagerAdapter extends FragmentPagerAdapter {
public TabsPagerAdapter(FragmentManager fm, MainActivity mainActivity){
super(fm);
}
// page index, fragment selector
#Override
public Fragment getItem(int index) {
switch (index)
{
case 0: return new FragmentPage1(); // bad practice
case 1: return new FragmentPage2(); // why should one do that?
case 2: return new FragmentPage3();
}
return null;
}
#Override
public int getCount() {
return 3;
}
}
What a piece of crap ^^ And I just copied it over and then totally forgot about it's existence ;)
Moved instanciation of fragments to constructor and keeped them for later use. Works perfectly now.
Class TabsPagerAdapter after optimization
public class TabsPagerAdapter extends FragmentPagerAdapter {
// hosted fragments
private FragmentPage fragmentPageBasic;
private FragmentPage fragmentPageAdvanced;
private FragmentPage fragmentPageSettings;
//constructor
public TabsPagerAdapter(FragmentManager fm, MainActivity mainActivity){
super(fm);
fragmentPageBasic = new FragmentPage();
fragmentPageBasic.setMainActivity(mainActivity);
fragmentPageBasic.setLayoutResource(R.layout.fragment_page1);
fragmentPageBasic.setAdBannerResource(R.id.adBannerBasic);
fragmentPageBasic.setAdBannerLayoutResource(R.id.adBannerBasicLayout);
fragmentPageAdvanced = new FragmentPage();
fragmentPageAdvanced.setMainActivity(mainActivity);
fragmentPageAdvanced.setLayoutResource(R.layout.fragment_page2);
fragmentPageAdvanced.setAdBannerResource(R.id.adBannerAdvanced);
fragmentPageAdvanced.setAdBannerLayoutResource(R.id.adBannerAdvancedLayout);
fragmentPageSettings = new FragmentSettingsPage();
fragmentPageSettings.setMainActivity(mainActivity);
fragmentPageSettings.setLayoutResource(R.layout.fragment_page3);
fragmentPageSettings.setAdBannerResource(R.id.adBannerSettings);
fragmentPageSettings.setAdBannerLayoutResource(R.id.adBannerSettingsLayout);
}
// page index, fragment selector
#Override
public Fragment getItem(int index) {
switch (index)
{
case 0: return fragmentPageBasic;
case 1: return fragmentPageAdvanced;
case 2: return fragmentPageSettings;
}
return null;
}
#Override
public int getCount() {
return 3;
}
// GETTERS
public FragmentPage getFragmentPageBasic() {return fragmentPageBasic;}
public FragmentPage getFragmentPageAdvanced() {return fragmentPageAdvanced;}
public FragmentPage getFragmentPageSettings() {return fragmentPageSettings;}
}
Instead of having redundant FragmentPage1, Fragment2, FragmentPage3 classes, of course now there is only FragmentPage and FragmentSettingsPage (extends FragmentPage to override OnCreateView method), which results in a much cleaner and more understandable code.
Class FragmentPage
public class FragmentPage extends Fragment {
protected MainActivity mainActivity;
// layout resource
protected int layoutResource;
// view
protected View rootView;
//Admob
protected AdView adBanner;
protected int adBannerResource;
protected int adBannerLayoutResource;
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
onCreate(inflater, container);
return rootView;
}
// manage common onCreate things
protected void onCreate(LayoutInflater inflater, ViewGroup container)
{
rootView = inflater.inflate(layoutResource, container, false);
// admob banner
adBanner = (AdView) rootView.findViewById(adBannerResource);
adBanner.setAdListener(new AdListener() {
#Override
public void onAdLoaded() {
}
#Override
public void onAdOpened() {
}
#Override
public void onAdClosed() {
newAdBannerRequest();
}
#Override
public void onAdFailedToLoad(int errorCode) {
newAdBannerRequest();
}
#Override
public void onAdLeftApplication() {
}
});
if(mainActivity.showAdBanners())
{
newAdBannerRequest();
showAdBanner();
}
else
hideAdBanner();
}
// ADMOB
public void newAdBannerRequest()
{
AdRequest request = new AdRequest.Builder()
.addTestDevice(AdRequest.DEVICE_ID_EMULATOR) // All emulators
.addTestDevice("XXXXXXXXXXXXXXXXXXXXXXXXXX") // My Galaxy Nexus test phone
.build();
adBanner.loadAd(request);
}
public void showAdBanner()
{
GridLayout adBannerLayout = (GridLayout) rootView.findViewById(adBannerLayoutResource);
if(adBannerLayout.getVisibility() == GridLayout.GONE)
adBannerLayout.setVisibility(GridLayout.VISIBLE);
}
public void hideAdBanner()
{
GridLayout adBannerLayout = (GridLayout) rootView.findViewById(adBannerLayoutResource);
if(adBannerLayout.getVisibility() == GridLayout.VISIBLE)
adBannerLayout.setVisibility(GridLayout.GONE);
}
// GETTERS
public AdView getAdBanner() { return adBanner;}
public View getRootView() { return rootView;}
// SETTERS
public void setMainActivity(MainActivity mainActivity) {this.mainActivity = mainActivity;}
public void setLayoutResource(int layoutResource){this.layoutResource = layoutResource;}
public void setAdBannerResource(int adBannerResource){this.adBannerResource = adBannerResource;}
public void setAdBannerLayoutResource(int adBannerLayoutResource){this.adBannerLayoutResource = adBannerLayoutResource;}
}
Class FragmentSettingsPage
public class FragmentSettingsPage extends FragmentPage {
// Preferences
public static final String PREFS_NAME = "Preferences";
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
super.onCreate(inflater, container);
SharedPreferences preferences = mainActivity.getSharedPreferences(PREFS_NAME, 0);
// do some other top secret stuff here ;)
return rootView;
}
}
Any ideas how to improve this further ?

Use import android.support.v4.app.Fragment instead import android.app.Fragment
Please add this in your gradle dependencies
compile 'com.android.support:support-v4:22.1.1'
Edit : please use findFragmentById(R.id.fragment_page1) instead R.layout
FragmentPage1 fragmentPage1 = (FragmentPage1) getSupportFragmentManager().findFragmentById(R.id.fragment_page1);