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Fragment tab not attached to a context

I'm currently making a soundboard app on android studio which has a ton of fragments. The first page on my tab layout is just a normal button view, but my second tabView has another fragmentView within it. The goal is for the first page to just show some normal sounds, and the second tab to have multiple operators to choose specific soundboards for.
Anyways, the app seems to work fine. I can switch from the main tab to the operator tab, and even select operator soundboard pages and be moved to their fragments. However as soon as I try to switch fragments (through my tabview) my app crashes and I get the error:
"Fragment operatorTab{4623fc9} (312d4e58-458c-4f47-8fa3-794fe15f0536)} not attached to a context."**
**at com.jkcarraher.rainbowsixsoundboard.operatorTab.resetAllButtons(operatorTab.java:113)
at com.jkcarraher.rainbowsixsoundboard.operatorTab.access$000(operatorTab.java:31)
at com.jkcarraher.rainbowsixsoundboard.operatorTab$2.onScrollChanged(operatorTab.java:107)
I attached my code below, please let me know if you have any ideas!
MainActivity.java
import android.graphics.Color;
import android.os.Bundle;
import android.text.SpannableString;
import android.text.Spanned;
import android.text.style.ForegroundColorSpan;
import android.widget.Adapter;
import android.widget.TextView;
import com.google.android.gms.ads.MobileAds;
import com.google.android.gms.ads.initialization.InitializationStatus;
import com.google.android.gms.ads.initialization.OnInitializationCompleteListener;
import com.google.android.material.tabs.TabLayout;
import androidx.viewpager.widget.ViewPager;
import androidx.appcompat.app.AppCompatActivity;
public class MainActivity extends AppCompatActivity {
private SectionsPageAdapter mSectionsPageAdapter;
private ViewPager mViewPager;
private TabLayout tabLayout;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
initializeAds();
makeSixYellow();
//Create ViewPager (that houses all fragments)
mSectionsPageAdapter = new SectionsPageAdapter(getSupportFragmentManager());
mViewPager = (ViewPager) findViewById(R.id.view_pager);
setUpViewPager(mViewPager);
//Add & customize tabs
tabLayout = (TabLayout) findViewById(R.id.tabs);
tabLayout.setTabTextColors(Color.WHITE, Color.WHITE);
tabLayout.setupWithViewPager(mViewPager);
tabLayout.getTabAt(0).setText("Utility");
tabLayout.getTabAt(1).setText("Voice Lines");
checkPageChange();
}
private void setUpViewPager(ViewPager viewPager) {
SectionsPageAdapter adapter = new SectionsPageAdapter(getSupportFragmentManager());
adapter.addFragment(new utilityTab(), "Utility");
adapter.addFragment(new voiceLinesView(), "Voice Lines");
viewPager.setAdapter(adapter);
}
private void makeSixYellow(){
TextView textView = findViewById(R.id.titleText);
String text = "R6 Soundboard";
SpannableString ss = new SpannableString(text);
ForegroundColorSpan fcsYellow = new ForegroundColorSpan(Color.rgb(255,236,141));
ss.setSpan(fcsYellow, 1,2, Spanned.SPAN_EXCLUSIVE_EXCLUSIVE);
textView.setText(ss);
}
private void initializeAds(){
MobileAds.initialize(this, new OnInitializationCompleteListener() {
#Override
public void onInitializationComplete(InitializationStatus initializationStatus) {
}
});
}
private void checkPageChange(){
mViewPager.addOnPageChangeListener(new ViewPager.OnPageChangeListener() {
#Override
public void onPageScrolled(int position, float positionOffset, int positionOffsetPixels) {
utilityTab.resetAllButtons();
}
#Override
public void onPageSelected(int position) {
utilityTab.resetAllButtons();
}
#Override
public void onPageScrollStateChanged(int state) {
utilityTab.resetAllButtons();
}
});
}
}
activity_main.xml
<?xml version="1.0" encoding="utf-8"?>
<androidx.coordinatorlayout.widget.CoordinatorLayout
xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
tools:context=".MainActivity">
<com.google.android.material.appbar.AppBarLayout
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:background="#color/colorHeader"
android:theme="#style/AppTheme.AppBarOverlay">
<TextView
android:id="#+id/titleText"
android:layout_marginLeft="20dp"
android:layout_marginTop="20dp"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:fontFamily="#font/avenir"
android:gravity="center_horizontal"
android:text="R6 Soundboard"
android:textColor="#FFF"
android:textSize="30sp" />
<com.google.android.material.tabs.TabLayout
android:id="#+id/tabs"
android:layout_width="match_parent"
android:layout_height="wrap_content"
app:tabTextColor="#fff"
android:background="#color/colorHeader" />
</com.google.android.material.appbar.AppBarLayout>
<androidx.viewpager.widget.ViewPager
android:id="#+id/view_pager"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:background="#color/colorBody"
app:layout_behavior="#string/appbar_scrolling_view_behavior" />
</androidx.coordinatorlayout.widget.CoordinatorLayout>
voiceLinesView.java (contains fragments so I can select an operator and it will take me to their soundboard fragment)
package com.jkcarraher.rainbowsixsoundboard;
import android.os.Bundle;
import androidx.fragment.app.Fragment;
import androidx.fragment.app.FragmentTransaction;
import androidx.viewpager.widget.ViewPager;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import com.google.android.material.tabs.TabLayout;
public class voiceLinesView extends Fragment {
private SectionsPageAdapter voiceLinesSectionsPageAdapter;
private ViewPager voiceLinesViewPager;
public voiceLinesView() {
// Required empty public constructor
}
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
View view = inflater.inflate(R.layout.fragment_voice_lines_view, container, false);
FragmentTransaction fragmentTransaction = getFragmentManager().beginTransaction();
fragmentTransaction.add(R.id.voiceLinesFrame, new operatorTab());
fragmentTransaction.commit();
return view;
}
}
fragment_voice_lines_view.xml
<?xml version="1.0" encoding="utf-8"?>
<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"
tools:context=".voiceLinesView">
<FrameLayout
android:id="#+id/voiceLinesFrame"
android:layout_width="match_parent"
android:layout_height="match_parent"/>
</FrameLayout>
operatorTab.java
package com.jkcarraher.rainbowsixsoundboard;
import android.annotation.SuppressLint;
import android.content.Context;
import android.graphics.Rect;
import android.media.MediaPlayer;
import android.net.Uri;
import android.os.Bundle;
import androidx.annotation.Nullable;
import androidx.fragment.app.Fragment;
import androidx.fragment.app.FragmentManager;
import androidx.fragment.app.FragmentTransaction;
import android.view.LayoutInflater;
import android.view.MotionEvent;
import android.view.View;
import android.view.ViewGroup;
import android.view.ViewTreeObserver;
import android.widget.RelativeLayout;
import android.widget.ScrollView;
import com.google.android.gms.ads.AdRequest;
import com.google.android.gms.ads.AdView;
import soup.neumorphism.NeumorphCardView;
import soup.neumorphism.ShapeType;
import static android.view.MotionEvent.ACTION_MOVE;
public class operatorTab extends Fragment {
private ScrollView scrollView;
public static RelativeLayout KapkanButton;
public static RelativeLayout GlazButton;
public static RelativeLayout FuzeButton;
public static RelativeLayout TachankaButton;
voiceLinesView voiceLinesView = new voiceLinesView();
#Nullable
#Override
public View onCreateView(LayoutInflater inflater, #Nullable ViewGroup container, #Nullable Bundle savedInstanceState) {
View view = inflater.inflate(R.layout.fragment_operator_tab, container, false);
//Initialize ScrollView
scrollView = view.findViewById(R.id.operatorScrollView);
//Initialize buttons 1-4
KapkanButton = view.findViewById(R.id.kapkanButton);
GlazButton = view.findViewById(R.id.glazButton);
FuzeButton = view.findViewById(R.id.fuzeButton);
TachankaButton = view.findViewById(R.id.tachankaButton);
//Make buttons 1-6 pressable
initPressableButton(KapkanButton);
initPressableButton(GlazButton);
initPressableButton(FuzeButton);
initPressableButton(TachankaButton);
scrollResetListener();
return view;
}
#SuppressLint("ClickableViewAccessibility")
private void initPressableButton(final RelativeLayout relativeLayout) {
relativeLayout.setBackgroundColor(getResources().getColor(R.color.colorBody));
final Rect r = new Rect();
relativeLayout.setOnTouchListener(new View.OnTouchListener() {
#Override
public boolean onTouch(View view, MotionEvent event) {
// get the View's Rect relative to its parent
view.getHitRect(r);
// offset the touch coordinates with the values from r
// to obtain meaningful coordinates
final float x = event.getX() + r.left;
final float y = event.getY() + r.top;
if(event.getAction() == MotionEvent.ACTION_DOWN) {
relativeLayout.setBackgroundColor(getResources().getColor(R.color.colorButtonPressed));
return true;
} else if(event.getAction() == MotionEvent.ACTION_UP) {
if (r.contains((int) x, (int) y)) {
relativeLayout.setBackgroundColor(getResources().getColor(R.color.colorBody));
//On Click Up
FragmentTransaction fr = getFragmentManager().beginTransaction();
fr.replace(R.id.voiceLinesFrame, new kapkanVoiceLines());
fr.commit();
}
}else if(event.getAction() == ACTION_MOVE){
if (!r.contains((int) x, (int) y)) {
relativeLayout.setBackgroundColor(getResources().getColor(R.color.colorBody));
}
return true;
}
return false;
}
});
}
private void scrollResetListener(){
scrollView.getViewTreeObserver().addOnScrollChangedListener(new ViewTreeObserver.OnScrollChangedListener() {
#Override
public void onScrollChanged() {
resetAllButtons();
}
});
}
public void resetAllButtons(){
KapkanButton.setBackgroundColor(getResources().getColor(R.color.colorBody));
GlazButton.setBackgroundColor(getResources().getColor(R.color.colorBody));
FuzeButton.setBackgroundColor(getResources().getColor(R.color.colorBody));
TachankaButton.setBackgroundColor(getResources().getColor(R.color.colorBody));
}
}
fragment_operator_tab.xml
<?xml version="1.0" encoding="utf-8"?>
<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=".operatorTab">
<ScrollView
android:id="#+id/operatorScrollView"
android:layout_width="match_parent"
android:layout_height="wrap_content">
<RelativeLayout
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:background="#color/colorBody">
<RelativeLayout
android:id="#+id/kapkanButton"
android:layout_width="match_parent"
android:layout_height="60sp"
android:orientation="horizontal">
<ImageView
android:id="#+id/kapkanIcon"
android:layout_width="50sp"
android:layout_height="50sp"
android:layout_marginTop="5sp"
android:layout_marginLeft="10sp"
android:src="#drawable/ic_kapkan"/>
<TextView
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_toRightOf="#id/kapkanIcon"
android:layout_marginLeft="10sp"
android:layout_marginTop="15sp"
android:layout_gravity="center"
android:fontFamily="#font/avenir"
android:text="Kapkan"
android:textColor="#ffffff"
android:textSize="25dp" />
<ImageView
android:layout_width="40sp"
android:layout_height="40sp"
android:layout_alignParentEnd="true"
android:layout_marginTop="10sp"
android:layout_marginEnd="10dp"
android:src="#drawable/ic_arrow_right" />
</RelativeLayout>
<RelativeLayout
android:id="#+id/glazButton"
android:layout_below="#+id/kapkanButton"
android:layout_width="match_parent"
android:layout_height="60sp"
android:orientation="horizontal">
<ImageView
android:id="#+id/glazIcon"
android:layout_width="50sp"
android:layout_height="50sp"
android:layout_marginTop="5sp"
android:layout_marginLeft="10sp"
android:src="#drawable/ic_glaz"/>
<TextView
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_toRightOf="#id/glazIcon"
android:layout_marginLeft="10sp"
android:layout_marginTop="15sp"
android:layout_gravity="center"
android:fontFamily="#font/avenir"
android:text="Glaz"
android:textColor="#ffffff"
android:textSize="25dp" />
<ImageView
android:layout_width="40sp"
android:layout_height="40sp"
android:layout_alignParentEnd="true"
android:layout_marginTop="10sp"
android:layout_marginEnd="10dp"
android:src="#drawable/ic_arrow_right" />
</RelativeLayout>
<RelativeLayout
android:id="#+id/fuzeButton"
android:layout_below="#+id/glazButton"
android:layout_width="match_parent"
android:layout_height="60sp"
android:orientation="horizontal">
<ImageView
android:id="#+id/fuzeIcon"
android:layout_width="50sp"
android:layout_height="50sp"
android:layout_marginTop="5sp"
android:layout_marginLeft="10sp"
android:src="#drawable/ic_fuze"/>
<TextView
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_toRightOf="#id/fuzeIcon"
android:layout_marginLeft="10sp"
android:layout_marginTop="15sp"
android:layout_gravity="center"
android:fontFamily="#font/avenir"
android:text="Fuze"
android:textColor="#ffffff"
android:textSize="25dp" />
<ImageView
android:layout_width="40sp"
android:layout_height="40sp"
android:layout_alignParentEnd="true"
android:layout_marginTop="10sp"
android:layout_marginEnd="10dp"
android:src="#drawable/ic_arrow_right" />
</RelativeLayout>
<RelativeLayout
android:id="#+id/tachankaButton"
android:layout_below="#+id/fuzeButton"
android:layout_width="match_parent"
android:layout_height="60sp"
android:orientation="horizontal">
<ImageView
android:id="#+id/tachankaIcon"
android:layout_width="50sp"
android:layout_height="50sp"
android:layout_marginTop="5sp"
android:layout_marginLeft="10sp"
android:src="#drawable/ic_tachanka"/>
<TextView
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_toRightOf="#id/tachankaIcon"
android:layout_marginLeft="10sp"
android:layout_marginTop="15sp"
android:layout_gravity="center"
android:fontFamily="#font/avenir"
android:text="Tachanka"
android:textColor="#ffffff"
android:textSize="25dp" />
<ImageView
android:layout_width="40sp"
android:layout_height="40sp"
android:layout_alignParentEnd="true"
android:layout_marginTop="10sp"
android:layout_marginEnd="10dp"
android:src="#drawable/ic_arrow_right" />
</RelativeLayout>
</RelativeLayout>
</ScrollView>
</FrameLayout>

Try to remove the ViewTreeObserver.OnScrollChangedListener when the fragment is destroyed this will avoid any listener that can be attached to a destroyed fragment context not to be triggered whenever you leave and come back to this fragment.
First: make a global field for the listener
public class operatorTab extends Fragment {
...
ViewTreeObserver.OnScrollChangedListener mScrollListener = new ViewTreeObserver.OnScrollChangedListener() {
#Override
public void onScrollChanged() {
resetAllButtons();
}
};
Then set the listener wit the created field
private void scrollResetListener(){
scrollView.getViewTreeObserver().addOnScrollChangedListener(mScrollListener);
}
Then remove the listener.. I believe it's typically should be in onDestroyView() >> but also try it in onStop() or onPause if it didn't work
This also will solve memory leak of this listener whenever its callback is triggered after the Fragment's view is destroyed
#Override
public void onDestroyView() {
super.onDestroyView();
scrollView.getViewTreeObserver().removeOnScrollChangedListener(mScrollListener);
}
UPDATE
onStop()/onPause() worked for me
The reason that it didn't work with onDestroyView() because the OperatorTab fragment is a part of one of the ViewPager pages; and by default ViewPager loads a number of close pages in the background to be ready for the next page scroll; loading this pages include some of the fragment lifecycle callbacks like onCreateView, onStart, but not onResume.
When you leave the OperatorTab by scrolling the ViewPager to the next tab/page; onDestroyView() won't be created if the ViewPager decides that OperatorTab is a part of the cached/close pages that the user might return back to it later; and therefore the listener still there and after a few swipes of the pager, the OperatorTab fragment can be detached from the context leaving the listener there with memory leaks...
So, the best way in ViewPager fragment (or any View that loads its fragments in advance) is to stop any listeners once you leave the page, i.e. in onPause or onStop callbacks and not waiting until they are destroyed.

A possible reason for this error is that you are calling getResources() NOT in an Activity without using a context. So, you need to use context.getResources() instead where context may be one of these here . In you instance, I think getContext() will work.
So, I think you should search for all the times you are calling getResources and see if you are using a context or not.
The explanation for this error in a simple way is that you are trying to access the context required in getResources() before the fragment is instantiated.

My buttons and Views do nothing after inflating the layout they are in so avoid null object error

My Main Activity. This is where all my code is.
package com.abhiandroid.tablayoutexample;
import android.content.Context;
import android.content.Intent;
import android.net.Uri;
import android.os.Bundle;
import android.support.design.widget.TabLayout;
import android.support.v4.app.Fragment;
import android.support.v4.app.FragmentManager;
import android.support.v4.app.FragmentTransaction;
import android.support.v7.app.AppCompatActivity;
import android.view.LayoutInflater;
import android.view.View;
import android.widget.Button;
import android.widget.FrameLayout;
import android.widget.ImageButton;
import android.widget.ImageView;
import android.widget.TextView;
import android.widget.VideoView;
import com.google.android.gms.ads.AdRequest;
import com.google.android.gms.ads.AdView;
import com.google.android.gms.ads.InterstitialAd;
import com.google.android.gms.ads.MobileAds;
public class MainActivity extends AppCompatActivity {
FrameLayout simpleFrameLayout;
TabLayout tabLayout;
ImageButton imageRopo;
Button btn_show;
InterstitialAd interstitialAd;
AdView adView1,adView2;
TextView textView;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
LayoutInflater layoutInflater= (LayoutInflater) this.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
View firstfrag =getLayoutInflater().inflate(R.layout.fragment_first,null);
View thirdfrag =getLayoutInflater().inflate(R.layout.fragment_third,null);
btn_show = (Button)thirdfrag.findViewById(R.id.bt_show);
adView1= (AdView)thirdfrag.findViewById(R.id.ad_view);
adView2= (AdView)thirdfrag.findViewById(R.id.ad_view2);
imageRopo = (ImageButton)firstfrag.findViewById(R.id.buttonropo);
textView = (TextView)firstfrag.findViewById(R.id.testview);
imageRopo.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View view) {
Intent intent = new Intent(android.content.Intent.ACTION_VIEW);
intent.setData(Uri.parse("https://www.youtube.com"));
startActivity(intent);
textView.setText("The button works");
}
});
MobileAds.initialize(this, "ca-app-pub-8708219564656739~8048449285");
AdRequest adRequest = new AdRequest.Builder().addTestDevice(AdRequest.DEVICE_ID_EMULATOR)
.addTestDevice("355696115338836").build();
adView1.loadAd(adRequest);
adView2.loadAd(adRequest);
interstitialAd = new InterstitialAd(this);
interstitialAd.setAdUnitId("ca-app-pub-8708219564656739/2401085524");
interstitialAd.loadAd(new AdRequest.Builder().addTestDevice(AdRequest.DEVICE_ID_EMULATOR)
.addTestDevice("355697115338836").build());
btn_show.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View view) {
interstitialAd.show();
}
});
// get the reference of FrameLayout and TabLayout
simpleFrameLayout = (FrameLayout) findViewById(R.id.simpleFrameLayout);
tabLayout = (TabLayout) findViewById(R.id.simpleTabLayout);
// Create a new Tab named "First"
TabLayout.Tab firstTab = tabLayout.newTab();
firstTab.setText("Apps"); // set the Text for the first Tab
firstTab.setIcon(R.drawable.app); // set an icon for the
// first tab
tabLayout.addTab(firstTab); // add the tab at in the TabLayout
// Create a new Tab named "Second"
TabLayout.Tab secondTab = tabLayout.newTab();
secondTab.setText("Products"); // set the Text for the second Tab
secondTab.setIcon(R.drawable.company); // set an icon for the second tab
tabLayout.addTab(secondTab); // add the tab in the TabLayout
// Create a new Tab named "Third"
TabLayout.Tab thirdTab = tabLayout.newTab();
thirdTab.setText("Donate"); // set the Text for the first Tab
thirdTab.setIcon(R.drawable.donation); // set an icon for the first tab
tabLayout.addTab(thirdTab); // add the tab at in the TabLayout
// perform setOnTabSelectedListener event on TabLayout
tabLayout.setOnTabSelectedListener(new TabLayout.OnTabSelectedListener() {
#Override
public void onTabSelected(TabLayout.Tab tab) {
// get the current selected tab's position and replace the fragment accordingly
Fragment fragment = null;
switch (tab.getPosition()) {
case 0:
fragment = new FirstFragment();
break;
case 1:
fragment = new SecondFragment();
break;
case 2:
fragment = new ThirdFragment();
break;
}
FragmentManager fm = getSupportFragmentManager();
FragmentTransaction ft = fm.beginTransaction();
ft.replace(R.id.simpleFrameLayout, fragment);
ft.setTransition(FragmentTransaction.TRANSIT_FRAGMENT_OPEN);
ft.commit();
}
#Override
public void onTabUnselected(TabLayout.Tab tab) {
}
#Override
public void onTabReselected(TabLayout.Tab tab) {
}
});
}
}
My activit_main.xml
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:layout_gravity="center"
android:clickable="true"
android:focusable="true"
android:gravity="center"
android:orientation="vertical"
tools:context=".MainActivity">
<android.support.design.widget.TabLayout
android:id="#+id/simpleTabLayout"
android:layout_width="match_parent"
android:layout_height="wrap_content"
app:tabBackground="#android:color/darker_gray"
app:tabIndicatorColor="#f00"
app:tabSelectedTextColor="#f00"
app:tabTextColor="#000" />
<FrameLayout
android:id="#+id/simpleFrameLayout"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:background="#9C27B0">
</FrameLayout>
</LinearLayout>
The buttons and views are in different fragments hence me having to inflate the layouts they are in.
This is my firstfragment.xml. This is where one of my button and one of my TextView is.
<ScrollView xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:background="#ffeadb"
tools:context=".FirstFragment">
<android.support.constraint.ConstraintLayout
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:background="#f7c5a8"
android:orientation="vertical"
tools:context=".FirstFragment"
tools:layout_editor_absoluteY="1dp">
<TextView
android:id="#+id/textView23"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginTop="4dp"
android:fontFamily="#font/roboto_bold"
android:gravity="center"
android:text="Why Choose China when you have the option for Indian?"
android:textSize="37sp"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintHorizontal_bias="0.0"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="parent" />
<ImageView
android:id="#+id/imageView"
android:layout_width="106dp"
android:layout_height="109dp"
android:layout_marginStart="24dp"
android:layout_marginLeft="24dp"
android:layout_marginTop="208dp"
android:layout_marginEnd="281dp"
android:layout_marginRight="281dp"
android:src="#drawable/tiktokl"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintHorizontal_bias="0.0"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="parent" />
<TextView
android:id="#+id/textView22"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginStart="12dp"
android:layout_marginLeft="12dp"
android:layout_marginTop="148dp"
android:layout_marginEnd="35dp"
android:layout_marginRight="35dp"
android:gravity="center"
android:text="Why Choose Chinese when you can choose an Indian Alternative."
android:textSize="16sp"
android:textStyle="bold"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintHorizontal_bias="0.255"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="parent" />
<ImageView
android:id="#+id/imageView3"
android:layout_width="114dp"
android:layout_height="114dp"
android:layout_marginStart="149dp"
android:layout_marginLeft="149dp"
android:layout_marginTop="192dp"
android:layout_marginEnd="148dp"
android:layout_marginRight="148dp"
android:src="#drawable/red_arrow"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="parent" />
<ImageButton
android:id="#+id/buttonropo"
android:layout_width="132dp"
android:layout_height="118dp"
android:layout_marginStart="281dp"
android:layout_marginLeft="281dp"
android:layout_marginTop="183dp"
android:layout_marginEnd="24dp"
android:layout_marginRight="24dp"
android:layout_marginBottom="5dp"
android:adjustViewBounds="true"
android:background="#android:color/transparent"
android:baselineAlignBottom="false"
android:cropToPadding="true"
android:src="#drawable/roposoapplog"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="parent" />
<TextView
android:id="#+id/testview"
android:layout_width="88dp"
android:layout_height="19dp"
android:layout_marginStart="168dp"
android:layout_marginLeft="168dp"
android:layout_marginTop="336dp"
android:layout_marginEnd="155dp"
android:layout_marginRight="155dp"
android:textSize="25sp"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintHorizontal_bias="0.0"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="parent" />
</android.support.constraint.ConstraintLayout>
</ScrollView>
My ThirdFragement Activity file is very empty.
package com.abhiandroid.tablayoutexample;
import android.os.Bundle;
import android.support.v4.app.Fragment;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.Button;
public class FirstFragment extends Fragment {
public FirstFragment() {
// Required empty public constructor
}
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
}
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
// Inflate the layout for this fragment
return inflater.inflate(R.layout.fragment_first, container, false);
}
}
Before inflating the layouts, I would get a null object error and after inflating them they no-longer seem to work. They don't do anything. As you can see in my MainActivity.java file I had made is so that when a user clicks a button it redirects them to a website. I even made a TextView that updates itself when the Button is clicked so that I know that the Button is working. I have spent days trying to fix this error and have made no progress. I suspect it is related to some code being wrong while making the fragments.

You should add the logic for your Fragment's views inside your Fragment class.
So, instead of doing the logic for the button in the Activity, do it under the Fragment onCreateView():
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
View v = inflater.inflate(R.layout.fragment_first, container, false);
imageRopo = (ImageButton) v.findViewById(R.id.buttonropo);
textView = (TextView) v.findViewById(R.id.testview);
imageRopo.setOnClickListener(new View.OnClickListener() { ...
// ... and so on
return v;
}

Switching between fragments in a layout with BottomNavigationView

This is my first attempt to develop an android application.
I have a MainActivity with ConstraintLayout that has BottomNavigationView. Whenever the first navigation item is selected, I want to display a list of category (displayed in a fragment), then whenever this category is selected, another list will be displayed for items related to that particular category (in another fragment).
I have read in (Android - fragment .replace() doesn't replace content - puts it on top) it states that "static fragments written in XML are unable to be replaced, it has to be in a fragment container", how does it look like?
I tried to create my fragment container, but there is something wrong when I try to get the ListView (grand child of the container)
categoriesListView = getView().findViewById(R.id.categoriesList);
returns null.
MainActivity
package com.alsowaygh.getitdone.view.main;
import android.os.Bundle;
import android.support.annotation.NonNull;
import android.support.design.widget.BottomNavigationView;
import android.support.v4.app.Fragment;
import android.support.v4.app.FragmentManager;
import android.support.v4.app.FragmentTransaction;
import android.support.v7.app.AppCompatActivity;
import android.util.Log;
import android.view.MenuItem;
import android.widget.TextView;
import com.alsowaygh.getitdone.R;
import com.alsowaygh.getitdone.view.services.CategoriesListFragment;
import com.alsowaygh.getitdone.view.services.OnCategorySelectedListener;
import com.alsowaygh.getitdone.view.services.ServicesListFragment;
public class MainActivity extends AppCompatActivity implements OnCategorySelectedListener {
private static final String TAG = "MainActivity";
FragmentManager fragmentManager;
FragmentTransaction fragmentTransaction;
private BottomNavigationView.OnNavigationItemSelectedListener mOnNavigationItemSelectedListener
= new BottomNavigationView.OnNavigationItemSelectedListener() {
#Override
public boolean onNavigationItemSelected(#NonNull MenuItem item) {
switch (item.getItemId()) {
case R.id.navigation_services:
// mTextMessage.setText(R.string.title_services);
CategoriesListFragment categoriesListFragment = new CategoriesListFragment();
fragmentTransaction.add(R.id.container, categoriesListFragment);
fragmentTransaction.commit();
return true;
case R.id.navigation_bookings:
// mTextMessage.setText(R.string.title_bookings);
return true;
case R.id.navigation_chats:
// mTextMessage.setText(R.string.title_chats);
return true;
case R.id.navigation_settings:
return true;
}
return false;
}
};
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
BottomNavigationView navigation = findViewById(R.id.navigation);
navigation.setOnNavigationItemSelectedListener(mOnNavigationItemSelectedListener);
fragmentManager = getSupportFragmentManager();
fragmentTransaction = fragmentManager.beginTransaction();
}
#Override
public void onCategorySelected(String category) {
Log.w(TAG, "Successfully created CategoryListFragment!");
}
}
activity_main layout
<?xml version="1.0" encoding="utf-8"?>
<android.support.constraint.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
xmlns:tools="http://schemas.android.com/tools"
android:id="#+id/container"
android:layout_width="match_parent"
android:layout_height="match_parent"
tools:context=".view.main.MainActivity">
<android.support.design.widget.BottomNavigationView
android:id="#+id/navigation"
android:layout_width="0dp"
android:layout_height="wrap_content"
android:layout_marginEnd="0dp"
android:layout_marginStart="0dp"
android:background="?android:attr/windowBackground"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintLeft_toLeftOf="parent"
app:layout_constraintRight_toRightOf="parent"
app:menu="#menu/navigation" />
</android.support.constraint.ConstraintLayout>
Fragment
package com.alsowaygh.getitdone.view.services;
import android.content.Context;
import android.content.Intent;
import android.os.Bundle;
import android.support.v4.app.Fragment;
import android.support.v4.app.FragmentTransaction;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.AdapterView;
import android.widget.ArrayAdapter;
import android.widget.ListView;
import com.alsowaygh.getitdone.R;
import com.alsowaygh.getitdone.view.main.MainActivity;
public class CategoriesListFragment extends Fragment {
private ListView categoriesListView;
OnCategorySelectedListener categoryListener;
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
final Bundle savedInstanceState) {
//initializing root view first to refer to it
View rootView = inflater.inflate(R.layout.activity_main, container, false);
//initializing ListView
categoriesListView = getView().findViewById(R.id.categoriesList);
//categories list
final String[] categories = {"first category", "second category", "third category", "Fourth category"};
//initializing and adding categories strings to the addapter
ArrayAdapter<String> arrayAdapter = new ArrayAdapter<>(this.getContext(),
R.layout.category_textview);
for (String c : categories) {
arrayAdapter.add(c);
}
categoriesListView.setAdapter(arrayAdapter);
//implement onListItemClick
categoriesListView.setOnItemClickListener(new AdapterView.OnItemClickListener() {
#Override
public void onItemClick(AdapterView<?> parent, View view, int position, long id) {
//retrieve string from categories list at clicked position
categoryListener.onCategorySelected(categories[position]);
}
});
return rootView;
}
#Override //to fource container activity to implement the OnCategorySelectedListener
public void onAttach(Context context) {
super.onAttach(context);
try{
categoryListener = (OnCategorySelectedListener) context;
}catch(ClassCastException e){
throw new ClassCastException(context.toString() + "must implement OnCategorySelectedListener");
}
}
}
fragments container
<FrameLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:id="#+id/fragment_container"
android:layout_width="match_parent"
android:layout_height="match_parent">
<fragment
android:id="#+id/categories_list_fragment"
android:name="com.alsowaygh.getitdone.view.services.CategoriesListFragment"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:layout_marginBottom="8dp"
android:layout_marginTop="8dp">
<ListView
android:id="#+id/categoriesList"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:layout_marginBottom="8dp"
android:layout_marginEnd="8dp"
android:layout_marginLeft="8dp"
android:layout_marginRight="8dp"
android:layout_marginStart="8dp"
android:layout_marginTop="8dp" />
</fragment>
</FrameLayout>
Your help will be much appreciated.

You need to add the FrameLayout container within the layout file of the MainActivity(activity_main), onclick of the buttons in BottomNavigationView replace with the fragment. In this way you have a Activity and the fragments are shown within the activity, on click of each menu item you can invoke to replace it with the fragments.
This should resolve your problem.
You need to change the layout as below in activity_main.xml.
<android.support.constraint.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
xmlns:tools="http://schemas.android.com/tools"
android:id="#+id/container"
android:layout_width="match_parent"
android:layout_height="match_parent"
tools:context=".view.main.MainActivity">
<FrameLayout
android:id="#+id/frame"
android:layout_width="match_parent"
android:layout_height="match_parent" />
<android.support.design.widget.BottomNavigationView
android:id="#+id/navigation"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_marginEnd="0dp"
android:layout_marginStart="0dp"
android:background="?android:attr/windowBackground"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintLeft_toLeftOf="parent"
app:layout_constraintRight_toRightOf="parent"
app:menu="#menu/navigation" />
</android.support.constraint.ConstraintLayout>
In the MainActivity code, you need to change as below:
case R.id.navigation_services:
// mTextMessage.setText(R.string.title_services);
CategoriesListFragment categoriesListFragment = new CategoriesListFragment();
fragmentTransaction.replace(R.id.frame, categoriesListFragment);
fragmentTransaction.commit();
return true;
In the fragment layout file change to LinearLayout:
<LinearLayout
android:id="#+id/categories_list_fragment"
android:name="com.alsowaygh.getitdone.view.services.CategoriesListFragment"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:layout_marginBottom="8dp"
android:layout_marginTop="8dp">
<ListView
android:id="#+id/categoriesList"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:layout_marginBottom="8dp"
android:layout_marginEnd="8dp"
android:layout_marginLeft="8dp"
android:layout_marginRight="8dp"
android:layout_marginStart="8dp"
android:layout_marginTop="8dp" />
</LinearLayout>
EDIT
In the fragment code, change the layout to the name of the fragment layout file(R.layout.fragment_layout_name).
View rootView = inflater.inflate(R.layout.fragment_layout_name, container, false);
//initializing ListView
categoriesListView = rootView.findViewById(R.id.categoriesList);

Fragment inflation from different flavors

I am learning Android and I cannot find the solution to a fragment instantiation error when they are in different flavors.
Setup:
I have a main fragment that is loaded into the main activity.
I have two favors: paid and free.
The main (common) part of the app doesn't have the fragment (layout + java files), I put them into the favors.
I get the following error when I try to run my program:
01-24 19:38:06.211 27417-27417/com.udacity.gradle.builditbigger.paid E/AndroidRuntime: FATAL EXCEPTION: main
Process: com.udacity.gradle.builditbigger.paid, PID: 27417
java.lang.RuntimeException: Unable to start activity ComponentInfo{com.udacity.gradle.builditbigger.paid/com.udacity.gradle.builditbigger.MainActivity}: android.view.InflateException: Binary XML file line #1: Binary XML file line #1: Error inflating class fragment
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2817)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2892)
at android.app.ActivityThread.-wrap11(Unknown Source:0)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1593)
at android.os.Handler.dispatchMessage(Handler.java:105)
at android.os.Looper.loop(Looper.java:164)
at android.app.ActivityThread.main(ActivityThread.java:6541)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.Zygote$MethodAndArgsCaller.run(Zygote.java:240)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:767)
Caused by: android.view.InflateException: Binary XML file line #1: Binary XML file line #1: Error inflating class fragment
Caused by: android.view.InflateException: Binary XML file line #1: Error inflating class fragment
Caused by: java.lang.NullPointerException
at java.lang.VMClassLoader.findLoadedClass(Native Method)
at java.lang.ClassLoader.findLoadedClass(ClassLoader.java:738)
at java.lang.ClassLoader.loadClass(ClassLoader.java:363)
at java.lang.ClassLoader.loadClass(ClassLoader.java:312)
at android.support.v4.app.Fragment.isSupportFragmentClass(Fragment.java:499)
at android.support.v4.app.FragmentManagerImpl.onCreateView(FragmentManager.java:3637)
at android.support.v4.app.FragmentController.onCreateView(FragmentController.java:111)
at android.support.v4.app.FragmentActivity.dispatchFragmentsOnCreateView(FragmentActivity.java:338)
at android.support.v4.app.BaseFragmentActivityApi14.onCreateView(BaseFragmentActivityApi14.java:39)
at android.support.v4.app.FragmentActivity.onCreateView(FragmentActivity.java:67)
at android.view.LayoutInflater.createViewFromTag(LayoutInflater.java:780)
at android.view.LayoutInflater.createViewFromTag(LayoutInflater.java:730)
at android.view.LayoutInflater.inflate(LayoutInflater.java:492)
at android.view.LayoutInflater.inflate(LayoutInflater.java:423)
at android.view.LayoutInflater.inflate(LayoutInflater.java:374)
at android.support.v7.app.AppCompatDelegateImplV9.setContentView(AppCompatDelegateImplV9.java:287)
at android.support.v7.app.AppCompatActivity.setContentView(AppCompatActivity.java:139)
at com.udacity.gradle.builditbigger.MainActivity.onCreate(MainActivity.java:14)
at android.app.Activity.performCreate(Activity.java:6975)
at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1213)
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2770)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2892)
at android.app.ActivityThread.-wrap11(Unknown Source:0)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1593)
at android.os.Handler.dispatchMessage(Handler.java:105)
at android.os.Looper.loop(Looper.java:164)
at android.app.ActivityThread.main(ActivityThread.java:6541)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.Zygote$MethodAndArgsCaller.run(Zygote.java:240)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:767)
I have tried many different versions of the fragment name because the error message tells me that the problem is with that, unfortunately none of them worked. Could you please help me to find the route cause of the issue (I mean not just the solution but why doesn't this work)? The code can be found on GitHub, but the relevant files are here:
src/java/com/udacity/gradle/builditbigger/MainActivity.java
package com.udacity.gradle.builditbigger;
import android.os.Bundle;
import android.support.v7.app.AppCompatActivity;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
public class MainActivity extends AppCompatActivity {
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
}
#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);
}
public void tellJoke(View view) {
new EndpointsAsyncTask().execute(this);
}
}
src/res/layout/activity_main.xml
<fragment xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:id="#+id/fragment"
android:layout_width="match_parent"
android:layout_height="match_parent"
tools:layout="#layout/fragment_main" />
src/free/java/com/udacity/gradle/builditbigger/free/MainActivityFragment.java
package com.udacity.gradle.builditbigger.free;
import android.os.Bundle;
import android.support.v4.app.Fragment;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import com.google.android.gms.ads.AdRequest;
import com.google.android.gms.ads.AdView;
import com.udacity.gradle.builditbigger.R;
/**
* A placeholder fragment containing a simple view.
*/
public class MainActivityFragment extends Fragment {
public MainActivityFragment() {
}
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
View root = inflater.inflate(R.layout.fragment_main, container, false);
AdView mAdView = (AdView) root.findViewById(R.id.adView);
// Create an ad request. Check logcat output for the hashed device ID to
// get test ads on a physical device. e.g.
// "Use AdRequest.Builder.addTestDevice("ABCDEF012345") to get test ads on this device."
AdRequest adRequest = new AdRequest.Builder()
.addTestDevice(AdRequest.DEVICE_ID_EMULATOR)
.build();
mAdView.loadAd(adRequest);
return root;
}
}
src/free/res/layout/fragment_main.xml
<RelativeLayout
xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:ads="http://schemas.android.com/apk/res-auto"
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.udacity.gradle.builditbigger.MainActivity">
<TextView
android:id="#+id/instructions_text_view"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="#string/instructions" />
<Button
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_below="#+id/instructions_text_view"
android:onClick="tellJoke"
android:text="#string/button_text" />
<com.google.android.gms.ads.AdView
android:id="#+id/adView"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignParentBottom="true"
android:layout_centerHorizontal="true"
ads:adSize="BANNER"
ads:adUnitId="#string/banner_ad_unit_id" />
</RelativeLayout>
src/paid/java/com/udacity/gradle/builditbigger/paid/MainActivityFragment.java
package com.udacity.gradle.builditbigger.paid;
import android.support.v4.app.Fragment;
import android.os.Bundle;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import com.udacity.gradle.builditbigger.R;
/**
* A placeholder fragment containing a simple view.
*/
public class MainActivityFragment extends Fragment {
public MainActivityFragment() {
}
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
View root = inflater.inflate(R.layout.fragment_main, container, false);
return root;
}
}
src/paid/res/layout/fragment_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: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.udacity.gradle.builditbigger.MainActivity">
<TextView
android:id="#+id/instructions_text_view"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="#string/instructions" />
<Button
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_below="#+id/instructions_text_view"
android:onClick="tellJoke"
android:text="#string/button_text" />
</RelativeLayout>

Meanwhile, I found the solution. In src/res/layout/activity_main.xml you need to give the android:name attribute to the fragment in order to make it work. The name is the same in both flavors (MainActivityFragment), but the namespaces are different (free and paid). The only way to resolve this issue is that you need to move this layout file to the flavor parts of the application, and delete the original from the main part. Long story short, you have to delete the src/res/layout/activity_main.xml file, and add these two files to the project:
src/free/res/layout/activity_main.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.udacity.gradle.builditbigger.free.MainActivityFragment"
android:layout_width="match_parent"
android:layout_height="match_parent"
tools:layout="#layout/fragment_main" />
src/paid/res/layout/activity_main.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.udacity.gradle.builditbigger.paid.MainActivityFragment"
android:layout_width="match_parent"
android:layout_height="match_parent"
tools:layout="#layout/fragment_main" />
I am sorry for the original question, but I hope that it will be useful for someone.

App crash after button click [duplicate]

This question already has answers here:
What is a NullPointerException, and how do I fix it?
(12 answers)
Closed 6 years ago.
I tried creating a simple app "MemeCrater" which i learned from one of youtube tutorial.but whenever i press the Create button.The App crashes.
This is the error i get.
Error
Process: com.example.iemshekhar.memegenerator, PID: 13118
java.lang.NullPointerException: Attempt to invoke interface method 'void com.example.iemshekhar.memegenerator.TopSectionFragment$TopSectionListener.createMeme(java.lang.String, java.lang.String)' on a null object reference
at com.example.iemshekhar.memegenerator.TopSectionFragment.buttonClicked(TopSectionFragment.java:57)
at com.example.iemshekhar.memegenerator.TopSectionFragment$1.onClick(TopSectionFragment.java:49)
at android.view.View.performClick(View.java:5697)
at android.widget.TextView.performClick(TextView.java:10815)
at android.view.View$PerformClick.run(View.java:22526)
at android.os.Handler.handleCallback(Handler.java:739)
at android.os.Handler.dispatchMessage(Handler.java:95)
at android.os.Looper.loop(Looper.java:158)
at android.app.ActivityThread.main(ActivityThread.java:7229)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1230)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:1120)
This is my main activity java file:
MainActivity.java
package com.example.iemshekhar.memegenerator;
import android.app.Fragment;
import android.support.v7.app.ActionBarActivity;
import android.os.Bundle;
import android.view.Menu;
import android.view.MenuItem;
public class MainActivity extends ActionBarActivity implements TopSectionFragment.TopSectionListener {
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
}
#Override
public void createMeme(String top, String bottom) {
BottomPictureFragment bottmfragment=(BottomPictureFragment)getFragmentManager().findFragmentById(R.id.fragment2);
bottmfragment.setMemeText(top,bottom);
}
#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);
}
}
This is my top Fragement java file:
TopSectionFragment.java
package com.example.iemshekhar.memegenerator;
import android.app.Activity;
import android.app.Fragment;
import android.content.Context;
import android.os.Bundle;
import android.support.annotation.Nullable;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.Button;
import android.widget.EditText;
import android.widget.TextView;
public class TopSectionFragment extends Fragment {
private static EditText top, bottom;
TopSectionListener activitycommander;
public interface TopSectionListener{
public void createMeme(String top,String bottom);
}
public void onAtttach(Context context)
{
try{
activitycommander=(TopSectionListener)context;
}
catch(ClassCastException e){
throw new ClassCastException(e.getMessage());
}
}
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
View view = inflater.inflate(R.layout.top_section_fragment, container, false);
top = (EditText)view.findViewById(R.id.toptextinput);
bottom = (EditText) view.findViewById(R.id.bottomtextinput);
final Button create = (Button) view.findViewById(R.id.createbutton);
create.setOnClickListener(
new Button.OnClickListener() {
public void onClick(View v) {
buttonClicked(v);
}
}
);
return view;
}
public void buttonClicked(View v) {
activitycommander.createMeme(top.getText().toString(),bottom.getText().toString());
}
}
This file is my bottom Fragment java File:
BottomSectionFragment.java
package com.example.iemshekhar.memegenerator;
import android.app.Fragment;
import android.os.Bundle;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.TextView;
/**
* Created by IEmShekhar on 6/18/2016.
*/
public class BottomPictureFragment extends Fragment {
public static TextView toptext,bottomtext;
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
View view = inflater.inflate(R.layout.bottom_picture_fragment, container, false);
toptext=(TextView)view.findViewById(R.id.textView1);
bottomtext=(TextView)view.findViewById(R.id.textView2);
return view;
}
public void setMemeText(String top,String bottom){
toptext.setText(top);
bottomtext.setText(bottom);
}
}
These are my XML Files:
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:background="#006669"
android:paddingTop="#dimen/activity_vertical_margin"
android:paddingBottom="#dimen/activity_vertical_margin" tools:context=".MainActivity">
<fragment
android:layout_width="wrap_content"
android:layout_height="290dp"
android:name="com.example.iemshekhar.memegenerator.BottomPictureFragment"
android:id="#+id/fragment2"
android:layout_alignParentBottom="true"
android:layout_centerHorizontal="true"
tools:layout="#layout/bottom_picture_fragment" />
<fragment
android:layout_width="400dp"
android:layout_height="wrap_content"
android:name="com.example.iemshekhar.memegenerator.TopSectionFragment"
android:id="#+id/fragment"
android:layout_alignParentTop="true"
android:layout_centerHorizontal="true"
tools:layout="#layout/top_section_fragment"
android:layout_above="#+id/fragment2" />
</RelativeLayout>
Top_section_Fragment.xml
<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent" android:layout_height="match_parent" android:background="#999999">
<EditText
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:id="#+id/toptextinput"
android:layout_centerHorizontal="true"
android:layout_marginTop="15dp"
android:width="300dp"/>
<EditText
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:id="#+id/bottomtextinput"
android:layout_centerHorizontal="true"
android:layout_below="#+id/toptextinput"
android:width="300dp"
android:layout_marginTop="30dp"
/>
<Button
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginTop="150dp"
android:layout_centerHorizontal="true"
android:text="#string/Create_text"
android:background="#006666"
android:textStyle="bold"
android:id="#+id/createbutton"/>
</RelativeLayout>
Bottom_picture_Fragement.xml
<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent" android:layout_height="match_parent"
android:background="#drawable/afaque">
<TextView
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:textAppearance="?android:attr/textAppearanceLarge"
android:text="#string/toptext"
android:textStyle="bold"
android:textSize="25sp"
android:background="#ffff"
android:width="400dp"
android:textAlignment="center"
android:id="#+id/textView1"
android:layout_alignParentTop="true"
android:layout_centerHorizontal="true" />
<TextView
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:textAppearance="?android:attr/textAppearanceLarge"
android:text="#string/bottomtext"
android:textStyle="bold"
android:textSize="25sp"
android:background="#ffff"
android:width="400dp"
android:textAlignment="center"
android:id="#+id/textView2"
android:layout_alignParentBottom="true"
android:layout_alignParentLeft="true"
android:layout_alignParentStart="true" />
</RelativeLayout>

Guessing that you're trying to set the text from editText, You should be accessing the text from your editText in your TopSectionFragment
Replace
//Initialize
`private static TextView top, bottom;`
//onCreateView() Method
top = (TextView) view.findViewById(R.id.textView1);
bottom = (TextView) view.findViewById(R.id.textView2);
with this
//Initialize
`private static EditText top, bottom;`
//onCreateView Method
//onCreateView() Method
top = (EditText) view.findViewById(R.id.toptextinput);
bottom = (EditText) view.findViewById(R.id.bottomtextinput);
in your TopSectionFragment. Hope this will help :)