I can't move from current activity to another activity

I can't move from current activity to another activity - java

when try to click on New Activity Button in my MainActivity , my app crash and closed . whit this error on screen " unfortunately[ App Name ] has stopped "
I google this problem and i can't find any Definitive solution.
here is logCat Log , First Java Source ( MainActivity.java ) and seccond java source ( Seccond.java ) .
Logcat Log :
05-03 00:05:17.750: E/AndroidRuntime(1091): FATAL EXCEPTION: main
05-03 00:05:17.750: E/AndroidRuntime(1091): Process: com.example.helloworld, PID: 1091
05-03 00:05:17.750: E/AndroidRuntime(1091): java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example.helloworld/com.example.helloworld.Seccond}: java.lang.IllegalArgumentException: No view found for id 0x7f05003c (com.example.helloworld:id/container) for fragment PlaceholderFragment{b2d2faf8 #0 id=0x7f05003c}
05-03 00:05:17.750: E/AndroidRuntime(1091): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2195)
05-03 00:05:17.750: E/AndroidRuntime(1091): at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2245)
05-03 00:05:17.750: E/AndroidRuntime(1091): at android.app.ActivityThread.access$800(ActivityThread.java:135)
05-03 00:05:17.750: E/AndroidRuntime(1091): at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1196)
05-03 00:05:17.750: E/AndroidRuntime(1091): at android.os.Handler.dispatchMessage(Handler.java:102)
05-03 00:05:17.750: E/AndroidRuntime(1091): at android.os.Looper.loop(Looper.java:136)
05-03 00:05:17.750: E/AndroidRuntime(1091): at android.app.ActivityThread.main(ActivityThread.java:5017)
05-03 00:05:17.750: E/AndroidRuntime(1091): at java.lang.reflect.Method.invokeNative(Native Method)
05-03 00:05:17.750: E/AndroidRuntime(1091): at java.lang.reflect.Method.invoke(Method.java:515)
05-03 00:05:17.750: E/AndroidRuntime(1091): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:779)
05-03 00:05:17.750: E/AndroidRuntime(1091): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:595)
05-03 00:05:17.750: E/AndroidRuntime(1091): at dalvik.system.NativeStart.main(Native Method)
05-03 00:05:17.750: E/AndroidRuntime(1091): Caused by: java.lang.IllegalArgumentException: No view found for id 0x7f05003c (com.example.helloworld:id/container) for fragment PlaceholderFragment{b2d2faf8 #0 id=0x7f05003c}
05-03 00:05:17.750: E/AndroidRuntime(1091): at android.support.v4.app.FragmentManagerImpl.moveToState(FragmentManager.java:919)
05-03 00:05:17.750: E/AndroidRuntime(1091): at android.support.v4.app.FragmentManagerImpl.moveToState(FragmentManager.java:1104)
05-03 00:05:17.750: E/AndroidRuntime(1091): at android.support.v4.app.BackStackRecord.run(BackStackRecord.java:682)
05-03 00:05:17.750: E/AndroidRuntime(1091): at android.support.v4.app.FragmentManagerImpl.execPendingActions(FragmentManager.java:1467)
05-03 00:05:17.750: E/AndroidRuntime(1091): at android.support.v4.app.FragmentActivity.onStart(FragmentActivity.java:570)
05-03 00:05:17.750: E/AndroidRuntime(1091): at android.app.Instrumentation.callActivityOnStart(Instrumentation.java:1171)
05-03 00:05:17.750: E/AndroidRuntime(1091): at android.app.Activity.performStart(Activity.java:5241)
05-03 00:05:17.750: E/AndroidRuntime(1091): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2168)
MainActivity.java
import android.support.v7.app.ActionBarActivity;
import android.support.v4.app.Fragment;
import android.content.Intent;
import android.os.Bundle;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import android.widget.Button;
import android.widget.ImageView;
import android.widget.TextView;
public class MainActivity extends ActionBarActivity {
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
// Start
Button btn_img = (Button) findViewById(R.id.btn_image);
Button btn = (Button) findViewById(R.id.btn_Click);
final TextView txt = (TextView) findViewById(R.id.txt_view);
Button btn_avtivity = ( Button) findViewById(R.id.btn_activity);
// For button click
btn.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View arg0) {
txt.setText(" Amin Bassam ");
}
});
// Image show
btn_img.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View arg0) {
ImageView img=(ImageView)findViewById(R.id.img_view);
img.setImageResource(R.drawable.amin);
}
});
btn_avtivity.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View arg0) {
Intent intent = new Intent(getApplicationContext(),Seccond.class);
startActivity(intent);
}
});
// Open Activities
if (savedInstanceState == null) {
getSupportFragmentManager().beginTransaction()
.add(R.id.container, new Fragment()).commit();
}
}
#Override
public boolean onCreateOptionsMenu(Menu menu) {
// Inflate the menu; this adds items to the action bar if it is present.
getMenuInflater().inflate(R.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();
if (id == R.id.action_settings) {
return true;
}
return super.onOptionsItemSelected(item);
}
/**
* A placeholder fragment containing a simple view.
*/
}
Seccond.java
package com.example.helloworld;
import android.os.Bundle;
import android.support.v4.app.Fragment;
import android.support.v7.app.ActionBarActivity;
import android.view.LayoutInflater;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import android.view.ViewGroup;
public class Seccond extends ActionBarActivity {
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_seccond);
if (savedInstanceState == null) {
getSupportFragmentManager().beginTransaction()
.add(R.id.container, new PlaceholderFragment()).commit();
}
}
#Override
public boolean onCreateOptionsMenu(Menu menu) {
// Inflate the menu; this adds items to the action bar if it is present.
getMenuInflater().inflate(R.menu.seccond, 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();
if (id == R.id.action_settings) {
return true;
}
return super.onOptionsItemSelected(item);
}
/**
* A placeholder fragment containing a simple view.
*/
public static class PlaceholderFragment extends Fragment {
public PlaceholderFragment() {
}
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
View rootView = inflater.inflate(R.layout.activity_seccond,
container, false);
return rootView;
}
}
}
Activity_main.Xml
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:id="#+id/container"
android:layout_width="match_parent"
android:layout_height="match_parent"
tools:context="com.example.helloworld.MainActivity"
tools:ignore="MergeRootFrame" >
<TextView
android:id="#+id/txt_view"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignLeft="#+id/btn_Click"
android:layout_alignParentTop="true"
android:layout_marginTop="98dp"
android:textAppearance="?android:attr/textAppearanceLarge" />
<Button
android:id="#+id/btn_Click"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignParentBottom="true"
android:layout_alignParentLeft="true"
android:layout_marginBottom="66dp"
android:text="Click"
tools:ignore="HardcodedText" />
"res/layout/activity_main.xml"
<Button
android:id="#+id/btn_image"
style="#style/AppTheme"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignBaseline="#+id/btn_Click"
android:layout_alignBottom="#+id/btn_Click"
android:layout_marginLeft="16dp"
android:layout_toRightOf="#+id/btn_Click"
android:text="Image"
tools:ignore="HardcodedText" />
<ImageView
android:id="#+id/img_view"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignLeft="#+id/btn_image"
android:layout_centerVertical="true"
android:scaleType="center"
android:src="#drawable/abc_ab_solid_light_holo"
tools:ignore="ContentDescription" />
<Button
android:id="#+id/btn_activity"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignParentRight="true"
android:layout_alignTop="#+id/btn_image"
android:text="New Activities"
tools:ignore="HardcodedText" />
</RelativeLayout>
Seccond_activity.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:background="#A8B007"
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.helloworld.Seccond$PlaceholderFragment" >
</RelativeLayout>
AndroidManifest.xml
<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="com.example.helloworld"
android:versionCode="1"
android:versionName="1.0" >
<uses-sdk
android:minSdkVersion="8"
android:targetSdkVersion="19" />
<application
android:allowBackup="true"
android:icon="#drawable/ic_launcher"
android:label="#string/app_name"
android:theme="#style/AppTheme" >
<activity
android:name="com.example.helloworld.MainActivity"
android:label="#string/app_name" >
<intent-filter>
<action android:name="android.intent.action.MAIN" />
<category android:name="android.intent.category.LAUNCHER" />
</intent-filter>
</activity>
<activity
android:name="com.example.helloworld.Seccond"
android:label="#string/app_name" >
</activity>
</application>
</manifest>

No view found for id 0x7f05003c (com.example.helloworld:id/container) for fragment PlaceholderFragment
The error is saying it cannot find the view with an id of container for the fragment placeholder to go into.
setContentView(R.layout.activity_seccond);
if (savedInstanceState == null) {
getSupportFragmentManager().beginTransaction()
.add(R.id.container, new PlaceholderFragment()).commit();
}
This part of the code is the main problem. In the add() for the getSupportFragmentManager, it is saying to create the fragment and put it in a view with the id container. But the layout specified in setContentView does not have a view with an id of container. So there needs to be a layout file with a View (like a frame) with an id of container, so that when the fragment layout loads, it can go into that view.
Try adding a file to layouts called activity_frame_seccond.xml with:
<FrameLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:id="#+id/container"
android:layout_width="match_parent"
android:layout_height="match_parent" />
Which is a frame with the id 'container'.
Change this line in Seccond.java:
setContentView(R.layout.activity_seccond);
for
setContentView(R.layout.activity_frame_seccond);
and see if that works.
With this code you are using the new file activity_frame_seccond.xml as the layout for the activity, and the first file activity_seccond.xml as the fragment that will put in the frame element (because it has the id container).
If this doesn't work let me know and I will have another look.

Check this line in your Fragment class :
View rootView = inflater.inflate(R.layout.activity_seccond,
container, false);
i think the Returned View is Null

Remove this line from your manifest
<activity
android:name="com.example.helloworld.Second"
android:label="#string/app_name" >
>
</activity>
and try

try in this way
#Override
public void onClick(View arg0) {
Intent intent = new Intent(this,Seccond.class);
startActivity(intent);
}

Related

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) {}
}

Unfortunately MyFirstApp has stopped

The problem arise when I use code for Button , I am referring to The new Boston tutorials.
I am doing exactly what is told but getting error in logcat.
package com.example.myfirstapp;
import android.support.v7.app.ActionBarActivity;
import android.support.v4.app.Fragment;
import android.os.Bundle;
import android.view.LayoutInflater;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import android.view.ViewGroup;
import android.widget.Button;
import android.widget.TextView;
public class MainActivity extends ActionBarActivity {
int counter=0;
TextView display;
Button add;
Button sub;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
add=(Button) findViewById(R.id.bAdd);
sub=(Button) findViewById(R.id.bSub);
display=(TextView) findViewById(R.id.tvDisplay);
add.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View arg0) {
// TODO Auto-generated method stub
counter++;
display.setText("Your Total is " +counter);
}
});
sub.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View arg0) {
// TODO Auto-generated method stub
counter--;
display.setText("Your Total is " +counter);
}
});
if (savedInstanceState == null) {
getSupportFragmentManager().beginTransaction()
.add(R.id.container, new PlaceholderFragment()).commit();
}
}
#Override
public boolean onCreateOptionsMenu(Menu menu) {
// Inflate the menu; this adds items to the action bar if it is present.
getMenuInflater().inflate(R.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();
if (id == R.id.action_settings) {
return true;
}
return super.onOptionsItemSelected(item);
}
/**
* A placeholder fragment containing a simple view.
*/
public static class PlaceholderFragment extends Fragment {
public PlaceholderFragment() {
}
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
View rootView = inflater.inflate(R.layout.fragment_main, container,
false);
return rootView;
}
}
}
This is my manifest file
<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="com.example.myfirstapp"
android:versionCode="1"
android:versionName="1.0" >
<uses-sdk
android:minSdkVersion="8"
android:targetSdkVersion="19" />
<application
android:allowBackup="true"
android:icon="#drawable/ic_launcher"
android:label="#string/app_name"
android:theme="#style/AppTheme" >
<activity
android:name=".MainActivity"
android:label="#string/app_name" >
<intent-filter>
<action android:name="android.intent.action.MAIN" />
<category android:name="android.intent.category.DEFAULT" />
<category android:name="android.intent.category.LAUNCHER" />
</intent-filter>
</activity>
</application>
</manifest>
Logcat file shows these errors
: FATAL EXCEPTION: main
Process: com.example.myfirstapp, PID: 1873
E/AndroidRuntime(1873): java.lang.RuntimeException: Unable to instantiate activity ComponentInfo{com.example.myfirstapp/com.example.myfirstapp.MainActivity}: java.lang.NullPointerException
E/AndroidRuntime(1873): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2121)
E/AndroidRuntime(1873):at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2245)
E/AndroidRuntime(1873):at android.app.ActivityThread.access$800(ActivityThread.java:135)
E/AndroidRuntime(1873): at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1196)
E/AndroidRuntime(1873): at android.os.Handler.dispatchMessage(Handler.java:102)
E/AndroidRuntime(1873): at android.os.Looper.loop(Looper.java:136)
E/AndroidRuntime(1873): at android.app.ActivityThread.main(ActivityThread.java:5017)
E/AndroidRuntime(1873): at java.lang.reflect.Method.invokeNative(Native Method)
E/AndroidRuntime(1873): at java.lang.reflect.Method.invoke(Method.java:515)
E/AndroidRuntime(1873): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:779)
E/AndroidRuntime(1873): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:595)
E/AndroidRuntime(1873): at dalvik.system.NativeStart.main(Native Method)
E/AndroidRuntime(1873): Caused by: java.lang.NullPointerException
E/AndroidRuntime(1873): at android.view.ViewConfiguration.get(ViewConfiguration.java:325)
E/AndroidRuntime(1873): at android.view.View.<init>(View.java:3448)
E/AndroidRuntime(1873): at android.view.View.<init>(View.java:3505)
E/AndroidRuntime(1873): at android.widget.TextView.<init>(TextView.java:623)
E/AndroidRuntime(1873): at android.widget.Button.<init>(Button.java:107)
E/AndroidRuntime(1873): at android.widget.Button.<init>(Button.java:103)
E/AndroidRuntime(1873): at android.widget.Button.<init>(Button.java:99)
E/AndroidRuntime(1873): at com.example.myfirstapp.MainActivity.<init>(MainActivity.java:18)
E/AndroidRuntime(1873): at java.lang.Class.newInstanceImpl(Native Method)
E/AndroidRuntime(1873): at java.lang.Class.newInstance(Class.java:1208)
E/AndroidRuntime(1873): at android.app.Instrumentation.newActivity(Instrumentation.java:1061)
E/AndroidRuntime(1873): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2112)
E/AndroidRuntime(1873): ... 11 more
: I/Process(1873): Sending signal. PID: 1873 SIG: 9
This is layout xml file
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical"
android:paddingBottom="#dimen/activity_vertical_margin"
android:paddingLeft="#dimen/activity_horizontal_margin"
android:paddingRight="#dimen/activity_horizontal_margin"
android:paddingTop="#dimen/activity_vertical_margin"
tools:context="com.example.myfirstapp.MainActivity$PlaceholderFragment" >
<TextView
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:text="#string/hello_world"
android:textSize="45sp"
android:layout_gravity="center"
android:gravity="center"
android:id="#+id/tvDisplay"
/>
<Button
android:layout_width="250dp"
android:layout_height="wrap_content"
android:text="#string/add_button"
android:gravity="center"
android:layout_gravity="center"
android:id="#+id/bAdd"
/>
<Button
android:id="#+id/bSub"
android:layout_width="250dp"
android:layout_height="wrap_content"
android:layout_gravity="center"
android:gravity="center"
android:text="#string/sub_button" />
</LinearLayout>
Please help me and please do not downvote me as I am very new and learning.

The fragment is holding the layout. You have to get the reference of buttons and textview from inflated view in onCreateView()
public static class PlaceholderFragment extends Fragment {
int counter=0;
TextView display;
Button add;
Button sub;
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
View rootView = inflater.inflate(R.layout.fragment_main, container,
false);
add = (Button) rootView.findViewById(R.id.bAdd);
sub = (Button) rootView.findViewById(R.id.bSub);
display = (TextView) rootView.findViewById(R.id.tvDisplay);
add.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View arg0) {
// TODO Auto-generated method stub
counter++;
display.setText("Your Total is " +counter);
}
});
sub.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View arg0) {
// TODO Auto-generated method stub
counter--;
display.setText("Your Total is " +counter);
}
});
return rootView;
}
}

You are initializing Button and TextView before fragment's view is created.
Move Button, TextView initialization and callback register code before return rootView statement or override onViewCreated(View view, Bundle savedInstanceState) function of PlaceholderFragment and put code inside that method.

Android app crash on startup

I really don't know whats wrong with this...
The app should only change the text of the text view when clicking a button, in this case the start button.
When I start the app with the virtual machine it crashes.
My code
package com.example.projectiii;
import android.support.v7.app.ActionBarActivity;
import android.support.v7.app.ActionBar;
import android.support.v4.app.Fragment;
import android.os.Bundle;
import android.view.LayoutInflater;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import android.view.View.OnClickListener;
import android.view.ViewGroup;
import android.widget.Button;
import android.widget.TextView;
import android.os.Build;
public class MainActivity extends ActionBarActivity {
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
if (savedInstanceState == null) {
getSupportFragmentManager().beginTransaction()
.add(R.id.container, new PlaceholderFragment()).commit();
}
Button btnS = (Button) findViewById(R.id.btStart);
btnS.setOnClickListener(new OnClickListener()
{
#Override
public void onClick(View view) {
// TODO Auto-generated method stub
TextView word = (TextView) findViewById(R.id.display);
word.setText("Project");
}
});
}
#Override
public boolean onCreateOptionsMenu(Menu menu) {
// Inflate the menu; this adds items to the action bar if it is present.
getMenuInflater().inflate(R.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();
if (id == R.id.action_settings) {
return true;
}
return super.onOptionsItemSelected(item);
}
/**
* A placeholder fragment containing a simple view.
*/
public static class PlaceholderFragment extends Fragment {
public PlaceholderFragment() {
}
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
View rootView = inflater.inflate(R.layout.fragment_main, container,
false);
return rootView;
}
}
}
My 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: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.projectiii.MainActivity$PlaceholderFragment" >
<EditText
android:id="#+id/text"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_below="#+id/display"
android:layout_centerHorizontal="true"
android:layout_marginTop="46dp"
android:ems="10" >
<requestFocus />
</EditText>
<Button
android:id="#+id/btStart"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignLeft="#+id/text"
android:layout_below="#+id/text"
android:layout_marginTop="42dp"
android:text="Start" />
<Button
android:id="#+id/btFinish"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignBottom="#+id/btStart"
android:layout_alignRight="#+id/text"
android:text="Finish" />
<Chronometer
android:id="#+id/time"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignParentTop="true"
android:layout_alignRight="#+id/text"
android:layout_marginTop="40dp"
android:text="Chronometer" />
<TextView
android:id="#+id/display"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_below="#+id/time"
android:layout_centerHorizontal="true"
android:layout_marginTop="66dp"
android:text="Text"
android:textSize="30sp" />
My logcat
05-03 15:06:48.720: E/AndroidRuntime(921): FATAL EXCEPTION: main
05-03 15:06:48.720: E/AndroidRuntime(921): Process: com.example.projectiii, PID: 921
05-03 15:06:48.720: E/AndroidRuntime(921): java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example.projectiii/com.example.projectiii.MainActivity}: java.lang.NullPointerException
05-03 15:06:48.720: E/AndroidRuntime(921): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2195)
05-03 15:06:48.720: E/AndroidRuntime(921): at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2245)
05-03 15:06:48.720: E/AndroidRuntime(921): at android.app.ActivityThread.access$800(ActivityThread.java:135)
05-03 15:06:48.720: E/AndroidRuntime(921): at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1196)
05-03 15:06:48.720: E/AndroidRuntime(921): at android.os.Handler.dispatchMessage(Handler.java:102)
05-03 15:06:48.720: E/AndroidRuntime(921): at android.os.Looper.loop(Looper.java:136)
05-03 15:06:48.720: E/AndroidRuntime(921): at android.app.ActivityThread.main(ActivityThread.java:5017)
05-03 15:06:48.720: E/AndroidRuntime(921): at java.lang.reflect.Method.invokeNative(Native Method)
05-03 15:06:48.720: E/AndroidRuntime(921): at java.lang.reflect.Method.invoke(Method.java:515)
05-03 15:06:48.720: E/AndroidRuntime(921): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:779)
05-03 15:06:48.720: E/AndroidRuntime(921): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:595)
05-03 15:06:48.720: E/AndroidRuntime(921): at dalvik.system.NativeStart.main(Native Method)
05-03 15:06:48.720: E/AndroidRuntime(921): Caused by: java.lang.NullPointerException
05-03 15:06:48.720: E/AndroidRuntime(921): at com.example.projectiii.MainActivity.onCreate(MainActivity.java:33)
05-03 15:06:48.720: E/AndroidRuntime(921): at android.app.Activity.performCreate(Activity.java:5231)
05-03 15:06:48.720: E/AndroidRuntime(921): at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1087)
05-03 15:06:48.720: E/AndroidRuntime(921): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2159)
05-03 15:06:48.720: E/AndroidRuntime(921): ... 11 more
05-03 15:06:48.760: W/ActivityManager(385): Force finishing activity com.example.projectiii/.MainActivity

Make sure the xml you posted is activity_main, not fragment_main. You don't need a Fragment here, so remove all Fragment-related code.

Bind the view of TextView here:
setContentView(R.layout.activity_main);
TextView word = (TextView) findViewById(R.id.display);

the layout xml you have shown is of the fragment(since it doesn't contain the R.id. container). You are trying to access the button element defined in your Fragment layout in your activity which is giving you he null pointer. Try accessing the button from the fragment class which will resolve your error.

Android start activity with button?

i keep getting a null pointer exception
I have a problem about starting a new activity via using button.
I already checked the previous questions related to mine problem, one of them is almost same but solutions didn't work out for me. So here is my problem.
whenever i start the app it crashes.
i have a main class called MainActivity and new Activity called login
Main class
public class MainActivity extends Activity {
Intent myIntent = new Intent(MainActivity.this, login.class);
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
Button loginButton = (Button) findViewById(R.id.button_login);
loginButton.setOnClickListener(new View.OnClickListener() {
public void onClick(View v) {
startActivity(myIntent);
}
});
}
#Override
public boolean onCreateOptionsMenu(Menu menu) {
// Inflate the menu; this adds items to the action bar if it is present.
getMenuInflater().inflate(R.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();
if (id == R.id.action_settings) {
return true;
}
return super.onOptionsItemSelected(item);
}
/**
* A placeholder fragment containing a simple view.
*/
public static class PlaceholderFragment extends Fragment {
public PlaceholderFragment() {
}
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
View rootView = inflater.inflate(R.layout.fragment_main, container, false);
return rootView;
}
}
}
logcat
02-18 10:27:42.520 1098-1098/com.example.app E/AndroidRuntime﹕ FATAL EXCEPTION: main
Process: com.example.app, PID: 1098
java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example.app/com.example.app.MainActivity}: java.lang.NullPointerException
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2195)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2245)
at android.app.ActivityThread.access$800(ActivityThread.java:135)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1196)
at android.os.Handler.dispatchMessage(Handler.java:102)
at android.os.Looper.loop(Looper.java:136)
at android.app.ActivityThread.main(ActivityThread.java:5017)
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:779)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:595)
at dalvik.system.NativeStart.main(Native Method)
Caused by: java.lang.NullPointerException
at com.example.app.MainActivity.onCreate(MainActivity.java:30)
at android.app.Activity.performCreate(Activity.java:5231)
at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1087)
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2159)
            at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2245)
            at android.app.ActivityThread.access$800(ActivityThread.java:135)
            at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1196)
            at android.os.Handler.dispatchMessage(Handler.java:102)
            at android.os.Looper.loop(Looper.java:136)
            at android.app.ActivityThread.main(ActivityThread.java:5017)
            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:779)
            at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:595)
            at dalvik.system.NativeStart.main(Native Method)
thanks in advance!!!
EDIT---> MANIFEST
<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="com.example.app" >
<application
android:allowBackup="true"
android:icon="#drawable/ic_launcher"
android:label="#string/app_name"
android:theme="#style/AppTheme" >
<activity
android:name="com.example.app.MainActivity"
android:label="#string/app_name" >
<intent-filter>
<action android:name="android.intent.action.MAIN" />
<category android:name="android.intent.category.LAUNCHER" />
</intent-filter>
</activity>
<activity
android:name="com.example.app.login"
android:label="#string/title_activity_login" >
<intent-filter>
<action android:name="android.intent.action.LOGIN" />
<category android:name="android.intent.category.DEFAULT" />
</intent-filter>
</activity>
</application>
</manifest>
MainActivity Layout
<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="com.example.app.MainActivity">
//login Button
<Button
android:layout_width="120dp"
android:layout_height="wrap_content"
android:text="Login"
android:id="#+id/button_login"
android:layout_marginBottom="160dp"
android:layout_alignParentBottom="true"
android:layout_alignParentLeft="true"
android:layout_alignParentStart="true"
android:layout_marginLeft="23dp" />
//high score button
<Button
android:layout_width="120dp"
android:layout_height="wrap_content"
android:text="high score"
android:id="#+id/highScore"
android:layout_alignTop="#+id/button_login"
android:layout_toRightOf="#+id/button_login"
android:layout_marginLeft="45dp" />
//play Button
<Button
android:layout_width="150dp"
android:layout_height="wrap_content"
android:text="Play"
android:id="#+id/Play"
android:layout_above="#+id/button_login"
android:layout_centerHorizontal="true"
android:layout_marginBottom="55dp" />
</RelativeLayout>
Edited corrections with imports
package com.example.app;
import android.app.Activity;
import android.content.Intent;
import android.support.v7.app.ActionBarActivity;
import android.support.v4.app.Fragment;
import android.os.Bundle;
import android.view.LayoutInflater;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import android.view.ViewGroup;
import android.widget.Button;
import android.widget.ImageButton;
public class MainActivity extends Activity {
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
Button loginButton = (Button) findViewById(R.id.button_login);
// if (savedInstanceState == null) {
// getSupportFragmentManager().beginTransaction()
// .add(R.id.container, new PlaceholderFragment())
// .commit();
// }
loginButton.setOnClickListener(new View.OnClickListener() {
public void onClick(View v) {
Intent myIntent = new Intent(MainActivity.this, login.class);
startActivity(myIntent);
}
});
}
#Override
public boolean onCreateOptionsMenu(Menu menu) {
// Inflate the menu; this adds items to the action bar if it is present.
getMenuInflater().inflate(R.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();
if (id == R.id.action_settings) {
return true;
}
return super.onOptionsItemSelected(item);
}
/**
* A placeholder fragment containing a simple view.
*/
public static class PlaceholderFragment extends Fragment {
public PlaceholderFragment() {
}
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
View rootView = inflater.inflate(R.layout.fragment_main, container, false);
return rootView;
}
}
}

Move this inside the onCreate method :
Intent myIntent = new Intent(MainActivity.this, login.class);
By using that line outside the method, you are referring to the instance of MainActivity before it is fully created.
Since it looks like you are only using that intent once, you could even move that line inside the onClick method of the loginButton's OnClickListener, as suggested by InnocentKiller.

Remove this line from top of your screen
Intent myIntent = new Intent(MainActivity.this, login.class);
and put under the button click event. So basically your code will something like this for MainActivity.
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
Button loginButton = (Button) findViewById(R.id.button_login);
loginButton.setOnClickListener(new View.OnClickListener() {
public void onClick(View v) {
Intent myIntent = new Intent(MainActivity.this, login.class);
startActivity(myIntent);
}
});
............
...........
}

Do you have the Login activity declared on your manifest as an activity
<activity
android:name="com.examlpe.app.loginActivity"/>

You need an Intent!
try:
loginButton.setOnClickListener(new View.OnClickListener() {
public void onClick(View v) {
Intent myIntent = new Intent(MainActivity.this, Login.class);
startActivity(myIntent);
}
});
Your login class should also be named "Login" to serve the name convention
And you need to add the new Login.class to your Manifest like
<activity
android:name="com.example.yourapp.Login"
android:label="#string/app_name"
<intent-filter>
<action android:name="android.intent.action.VIEW" />
<category android:name="android.intent.category.DEFAULT" />
</intent-filter>
</activity

java.lang.NullPointerException in MainAcitivity setOnClickListener

When I run my application, I keep getting a NullPointerException on line 56 as shown in the debug log below. I am relatively new to programming android applications, so I can't figure out what's going on here. Can someone please help me out with this?
My MainActivity.java:
package com.termite.pockettube;
import java.util.Locale;
import android.content.Intent;
import android.os.Bundle;
import android.support.v4.app.Fragment;
import android.support.v4.app.FragmentActivity;
import android.support.v4.app.FragmentManager;
import android.support.v4.app.FragmentPagerAdapter;
import android.support.v4.app.NavUtils;
import android.support.v4.view.ViewPager;
import android.view.Gravity;
import android.view.LayoutInflater;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import android.view.View.OnClickListener;
import android.view.ViewGroup;
import android.widget.Button;
import android.widget.TextView;
public class MainActivity extends FragmentActivity implements View.OnClickListener{
/**
* The {#link android.support.v4.view.PagerAdapter} that will provide
* fragments for each of the sections. We use a
* {#link android.support.v4.app.FragmentPagerAdapter} derivative, which
* will keep every loaded fragment in memory. If this becomes too memory
* intensive, it may be best to switch to a
* {#link android.support.v4.app.FragmentStatePagerAdapter}.
*/
SectionsPagerAdapter mSectionsPagerAdapter;
/**
* The {#link ViewPager} that will host the section contents.
*/
ViewPager mViewPager;
Button button;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
// Create the adapter that will return a fragment for each of the three
// primary sections of the app.
mSectionsPagerAdapter = new SectionsPagerAdapter(
getSupportFragmentManager());
// Set up the ViewPager with the sections adapter.
mViewPager = (ViewPager) findViewById(R.id.pager);
mViewPager.setAdapter(mSectionsPagerAdapter);
button = (Button) findViewById(R.id.button);
button.setOnClickListener(this); //this is line 56
}
public void countryOnClick() {
startActivity(new Intent("com.termite.pockettube.COUNTRY"));
}
#Override
public void onClick(View v) {
switch (v.getId()){
case R.id.button:
countryOnClick();
break;
}
}
#Override
public boolean onCreateOptionsMenu(Menu menu) {
// Inflate the menu; this adds items to the action bar if it is present.
getMenuInflater().inflate(R.menu.main, menu);
return true;
}
/**
* A {#link FragmentPagerAdapter} that returns a fragment corresponding to
* one of the sections/tabs/pages.
*/
public class SectionsPagerAdapter extends FragmentPagerAdapter {
public SectionsPagerAdapter(FragmentManager fm) {
super(fm);
}
#Override
public Fragment getItem(int position) {
// getItem is called to instantiate the fragment for the given page.
// Return a DummySectionFragment (defined as a static inner class
// below) with the page number as its lone argument.
switch (position) {
case 0:
Fragment1 fragment1 = new Fragment1();
return fragment1;
case 1:
Fragment2 fragment2 = new Fragment2();
return fragment2;
case 2:
Fragment3 fragment3 = new Fragment3();
return fragment3;
case 3:
Fragment4 fragment4 = new Fragment4();
return fragment4;
case 4:
Fragment5 fragment5 = new Fragment5();
return fragment5;
}
return null;
}
#Override
public int getCount() {
// Show 5 total pages.
return 5;
}
#Override
public CharSequence getPageTitle(int position) {
Locale l = Locale.getDefault();
switch (position) {
case 0:
return getString(R.string.title_section1).toUpperCase(l);
case 1:
return getString(R.string.title_section2).toUpperCase(l);
case 2:
return getString(R.string.title_section3).toUpperCase(l);
case 3:
return getString(R.string.title_section4).toUpperCase(l);
case 4:
return getString(R.string.title_section5).toUpperCase(l);
}
return null;
}
}
}
This is my debug log when attempting to run the application:
12-20 01:13:26.898: D/AndroidRuntime(6539): Shutting down VM
12-20 01:13:26.906: W/dalvikvm(6539): threadid=1: thread exiting with uncaught exception (group=0x40af21f8)
12-20 01:13:26.906: E/AndroidRuntime(6539): FATAL EXCEPTION: main
12-20 01:13:26.906: E/AndroidRuntime(6539): java.lang.RuntimeException: Unable to start activity ComponentInfo{com.termite.pockettube/com.termite.pockettube.MainActivity}: java.lang.NullPointerException
12-20 01:13:26.906: E/AndroidRuntime(6539): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2035)
12-20 01:13:26.906: E/AndroidRuntime(6539): at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2060)
12-20 01:13:26.906: E/AndroidRuntime(6539): at android.app.ActivityThread.access$600(ActivityThread.java:127)
12-20 01:13:26.906: E/AndroidRuntime(6539): at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1181)
12-20 01:13:26.906: E/AndroidRuntime(6539): at android.os.Handler.dispatchMessage(Handler.java:99)
12-20 01:13:26.906: E/AndroidRuntime(6539): at android.os.Looper.loop(Looper.java:137)
12-20 01:13:26.906: E/AndroidRuntime(6539): at android.app.ActivityThread.main(ActivityThread.java:4558)
12-20 01:13:26.906: E/AndroidRuntime(6539): at java.lang.reflect.Method.invokeNative(Native Method)
12-20 01:13:26.906: E/AndroidRuntime(6539): at java.lang.reflect.Method.invoke(Method.java:511)
12-20 01:13:26.906: E/AndroidRuntime(6539): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:784)
12-20 01:13:26.906: E/AndroidRuntime(6539): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:551)
12-20 01:13:26.906: E/AndroidRuntime(6539): at dalvik.system.NativeStart.main(Native Method)
12-20 01:13:26.906: E/AndroidRuntime(6539): Caused by: java.lang.NullPointerException
12-20 01:13:26.906: E/AndroidRuntime(6539): at com.termite.pockettube.MainActivity.onCreate(MainActivity.java:56)
12-20 01:13:26.906: E/AndroidRuntime(6539): at android.app.Activity.performCreate(Activity.java:4635)
12-20 01:13:26.906: E/AndroidRuntime(6539): at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1049)
12-20 01:13:26.906: E/AndroidRuntime(6539): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1999)
12-20 01:13:26.906: E/AndroidRuntime(6539): ... 11 more
Manifest xml code:
<uses-sdk
android:minSdkVersion="11"
android:targetSdkVersion="19" />
<application
android:allowBackup="true"
android:icon="#drawable/ic_launcher"
android:label="#string/app_name"
android:theme="#style/AppTheme" >
<activity
android:name="com.termite.pockettube.MainActivity"
android:label="#string/app_name" >
<intent-filter>
<action android:name="android.intent.action.MAIN" />
<category android:name="android.intent.category.LAUNCHER" />
</intent-filter>
</activity>
<activity
android:name="com.termite.pockettube.CountryActivity"
android:label="#string/title_activity_country" >
<intent-filter>
<action android:name="com.termite.pockettube.COUNTRY" />
<category android:name="android.intent.category.DEFAULT" />
</intent-filter>
</activity>
</application>
</manifest>
activity_main.xml:
<android.support.v4.view.ViewPager xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:id="#+id/pager"
android:layout_width="match_parent"
android:layout_height="match_parent"
tools:context=".MainActivity" >
<android.support.v4.view.PagerTabStrip
android:id="#+id/pager_title_strip"
android:layout_width="match_parent"
android:layout_height="50dp"
android:layout_gravity="top"
android:background="#33b5e5"
android:paddingBottom="4dp"
android:paddingTop="4dp"
android:textColor="#fff"
>
</android.support.v4.view.PagerTabStrip>
</android.support.v4.view.ViewPager>
fragment1.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: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=".MainActivity$DummySectionFragment" >
<Button
android:id="#+id/button"
android:layout_width="match_parent"
android:layout_height="50dp"
android:layout_alignParentTop="true"
android:text="#string/button" />
</RelativeLayout>

You need to button in activity_main.xml as you had added that button in fragment_1.xml this is is the cause of NPE.
add button in activity_main.xml will solve your problem
**activity_main.xml
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:padding="#dimen/padding_Small"
android:shrinkColumns="*"
android:stretchColumns="*" >
<android.support.v4.view.ViewPager
xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:id="#+id/pager"
android:layout_width="match_parent"
android:layout_height="match_parent"
tools:context=".MainActivity" >
<android.support.v4.view.PagerTabStrip
android:id="#+id/pager_title_strip"
android:layout_width="match_parent"
android:layout_height="50dp"
android:layout_gravity="top"
android:background="#33b5e5"
android:paddingBottom="4dp"
android:paddingTop="4dp"
android:textColor="#fff" />
</android.support.v4.view.ViewPager>
<Button
android:id="#+id/button"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_alignParentLeft="true"
android:layout_alignParentTop="true"
android:text="ButtonText" />
</RelativeLayout>

button = (Button) findViewById(R.id.button);
button.setOnClickListener(this); //this is line 56
button is null. Initialization fails
Need button in activity_main.xml and also id should be button
findViewById looks for a view with the id in the current inflated layout. So if you have button in activity_main.xml then your initialization works else you get NPE`
There is no button in activity_main.xml. S0 button = (Button) findViewById(R.id.button); fails
Button is in fragment1. So you will need to inflate the layout fragment1.xml and then initialize the button in onCreateView not initialize button in Activity.

Thank you all for your input, and it all worked to end the NPE, yet it didn't perform the task I wanted it to complete. I added the button to ,y Fragment1.java file and then it worked.
package com.termite.pockettube;
import com.termite.pockettube.MainActivity.SectionsPagerAdapter;
import android.content.Intent;
import android.os.Bundle;
import android.support.v4.app.Fragment;
import android.support.v4.view.ViewPager;
import android.view.LayoutInflater;
import android.view.View;
import android.view.View.OnClickListener;
import android.view.ViewGroup;
import android.widget.Button;
public class Fragment1 extends Fragment implements View.OnClickListener {
Button button;
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
// Get the view from fragmenttab1.xml
View view = inflater.inflate(R.layout.fragment1, container, false);
button = (Button)view.findViewById(R.id.button);
button.setOnClickListener(this);
return view;
}
/* #Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
}*/
public void countryOnClick() {
startActivity(new Intent("com.termite.pockettube.COUNTRY"));
}
#Override
public void onClick(View v) {
switch (v.getId()){
case R.id.button:
countryOnClick();
break;
}
}
}

Try
Button button = (Button) findViewById(R.id.button);
button.setOnClickListener(buttonListener);
in onCreate
Then try
private OnClickListener buttonListener = new OnClickListener() {
public void onClick(View v) {
//Do Work Here
}
};

Check R.id.button, button is it in R.layout.activity_main layout..
Post your activity_main.xml layout.
Do below thing.
Add your Button in activity_main.xml or change code
button = (Button) mViewPager.findViewById(R.id.button);
button.setOnClickListener(this);

Your error is in the getItem(poistion) method. even your adapter size is 5, it give you positions grater than 5. at such moments you return null from there.
you can check this by adding a Log statement to print the position value at the beginning of the getItem method

Button button=(Button)findViewById(R.id.button);
button.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) { Toast.makeText(MainActivity.this,"RunAPP",Toast.LENGTH_LONG).show();
}
});

We Keep Coding

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I can't move from current activity to another activity - java

Check this line in your Fragment class : View rootView = inflater.inflate(R.layout.activity_seccond, container, false); i think the Returned View is Null

Remove this line from your manifest <activity android:name="com.example.helloworld.Second" android:label="#string/app_name" > > </activity> and try

try in this way #Override public void onClick(View arg0) { Intent intent = new Intent(this,Seccond.class); startActivity(intent); }

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