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Inflation exception error from android

Hello i'm struggling with these error for past of couple of hours to no avail. I am trying to pass data from my activity to the fragment but not succeeding in doing so. My guess it's complaining about my <fragment> in activity_second.xml file. My guess might be wrong. Has anyone encountered this error? But i don't know how to resolve this error.Would some please guide in me what i did wrong. Below is my code:
first_fragment.xml:
<LinearLayout
xmlns:android="http://schemas.android.com/apk/res/android"
android:orientation="vertical"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:id="#+id/fragmentPic" >
<TextView
android:id="#+id/textName"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="#string/users_FirstName"
android:textSize="#dimen/font_size"
android:layout_gravity="center_horizontal"/>
<com.facebook.login.widget.ProfilePictureView
android:id="#+id/profilePic"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_gravity="center_horizontal"
>
</com.facebook.login.widget.ProfilePictureView>
</LinearLayout>
FirstFragment.java:
public class FirstFragment extends Fragment {
private ProfilePictureView profilePictureView;
private TextView textView;
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
// return super.onCreateView(inflater, container, savedInstanceState);
View rootView = inflater.inflate(R.layout.first_fragment, container, false);
Bundle bundle = new Bundle();
bundle = this.getArguments();
String profileId = bundle.getString("profileId"); //complains here and returns null
TextView textView = (TextView)rootView.findViewById(R.id.textName);
textView.setText(bundle.getString("names"));
return rootView;
}
}
activity_second.xml:
<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:background="#color/backgroundColor"
>
<include android:id="#+id/toolBar"
layout="#layout/toolbar" />
<android.support.v4.widget.DrawerLayout
android:layout_width="match_parent"
android:layout_height="match_parent"
android:id="#+id/drawer">
<fragment
android:layout_width="match_parent"
android:layout_height="match_parent"
tools:layout="#layout/first_fragment"
class="edu.sjsu.cmpe277.termproject.Fragments.FirstFragment"
android:id="#+id/fragment1"
/>
</android.support.v4.widget.DrawerLayout>
</LinearLayout>
secondActivity.java:
public class secondActivity extends AppCompatActivity {
private Intent intent;
private Toolbar toolbar;
private String firstName, profileId;
private FirstFragment firstFragment;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_second);
intent = getIntent();
firstName = intent.getStringExtra("firstName");
profileId = intent.getStringExtra("Id");
toolbar = (Toolbar)findViewById(R.id.toolBar);
setSupportActionBar(toolbar);
toolbar.setLogo(R.drawable.ic_menu_image);
getSupportActionBar().setDisplayShowHomeEnabled(true);
getSupportActionBar().setDisplayShowTitleEnabled(false);
firstFragment = new FirstFragment();
Bundle bundle = new Bundle();
bundle.putString("names", firstName);
bundle.putString("profileId", profileId);
firstFragment.setArguments(bundle);
FragmentManager manager = getSupportFragmentManager();
FragmentTransaction transaction = manager.beginTransaction();
transaction.add(R.id.drawer, firstFragment,"newFrag").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.menu_second, 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.
switch(item.getItemId()) {
case android.R.id.home:
Intent homeIntent = new Intent(this, secondActivity.class );
homeIntent.addFlags(Intent.FLAG_ACTIVITY_CLEAR_TOP);
startActivity(homeIntent);
}
int id = item.getItemId();
//noinspection SimplifiableIfStatement
if (id == R.id.action_settings) {
return true;
}
return super.onOptionsItemSelected(item);
}
}
And this error below:
29 01:50:11.402 13536-13536/edu.sjsu.cmpe277.termproject E/AndroidRuntime﹕ FATAL EXCEPTION: main
Process: edu.sjsu.cmpe277.termproject, PID: 13536
java.lang.RuntimeException: Unable to start activity ComponentInfo{edu.sjsu.cmpe277.termproject/edu.sjsu.cmpe277.termproject.secondActivity}: android.view.InflateException: Binary XML file line #82: Error inflating class fragment
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2693)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2758)
at android.app.ActivityThread.access$900(ActivityThread.java:177)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1448)
at android.os.Handler.dispatchMessage(Handler.java:102)
at android.os.Looper.loop(Looper.java:145)
at android.app.ActivityThread.main(ActivityThread.java:5942)
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:1399)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:1194)
Caused by: android.view.InflateException: Binary XML file line #82: Error inflating class fragment
at android.view.LayoutInflater.createViewFromTag(LayoutInflater.java:770)
at android.view.LayoutInflater.rInflate(LayoutInflater.java:813)
at android.view.LayoutInflater.rInflate(LayoutInflater.java:821)
at android.view.LayoutInflater.inflate(LayoutInflater.java:511)
at android.view.LayoutInflater.inflate(LayoutInflater.java:415)
at android.view.LayoutInflater.inflate(LayoutInflater.java:366)
at android.support.v7.app.AppCompatDelegateImplV7.setContentView(AppCompatDelegateImplV7.java:255)
at android.support.v7.app.AppCompatActivity.setContentView(AppCompatActivity.java:109)
at edu.sjsu.cmpe277.termproject.secondActivity.onCreate(secondActivity.java:43)
at android.app.Activity.performCreate(Activity.java:6289)
at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1119)
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2646)
            at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2758)
            at android.app.ActivityThread.access$900(ActivityThread.java:177)
            at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1448)
            at android.os.Handler.dispatchMessage(Handler.java:102)
            at android.os.Looper.loop(Looper.java:145)
            at android.app.ActivityThread.main(ActivityThread.java:5942)
            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:1399)
            at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:1194)
Caused by: java.lang.NullPointerException: Attempt to invoke virtual method 'java.lang.String android.os.Bundle.getString(java.lang.String)' on a null object reference
at edu.sjsu.cmpe277.termproject.Fragments.FirstFragment.onCreateView(FirstFragment.java:44)
at android.support.v4.app.Fragment.performCreateView(Fragment.java:1962)
at android.support.v4.app.FragmentManagerImpl.moveToState(FragmentManager.java:995)
at android.support.v4.app.FragmentManagerImpl.moveToState(FragmentManager.java:1185)
at android.support.v4.app.FragmentManagerImpl.addFragment(FragmentManager.java:1287)
at android.support.v4.app.FragmentManagerImpl.onCreateView(FragmentManager.java:2243)
at android.support.v4.app.FragmentController.onCreateView(FragmentController.java:111)
at android.support.v4.app.FragmentActivity.dispatchFragmentsOnCreateView(FragmentActivity.java:278)
at android.support.v4.app.BaseFragmentActivityHoneycomb.onCreateView(BaseFragmentActivityHoneycomb.java:31)
at android.support.v4.app.FragmentActivity.onCreateView(FragmentActivity.java:78)
at android.view.LayoutInflater.createViewFromTag(LayoutInflater.java:740)
            at android.view.LayoutInflater.rInflate(LayoutInflater.java:813)
            at android.view.LayoutInflater.rInflate(LayoutInflater.java:821)
            at android.view.LayoutInflater.inflate(LayoutInflater.java:511)
            at android.view.LayoutInflater.inflate(LayoutInflater.java:415)
            at android.view.LayoutInflater.inflate(LayoutInflater.java:366)
            at android.support.v7.app.AppCompatDelegateImplV7.setContentView(AppCompatDelegateImplV7.java:255)
            at android.support.v7.app.AppCompatActivity.setContentView(AppCompatActivity.java:109)
            at edu.sjsu.cmpe277.termproject.secondActivity.onCreate(secondActivity.java:43)
            at android.app.Activity.performCreate(Activity.java:6289)
            at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1119)
            at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2646)
            at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2758)
            at android.app.ActivityThread.access$900(ActivityThread.java:177)
            at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1448)
            at android.os.Handler.dispatchMessage(Handler.java:102)
            at android.os.Looper.loop(Looper.java:145)
            at android.app.ActivityThread.main(ActivityThread.java:5942)
            at java.lang.reflect.Method.invoke(Native Method)
            at java.lang.reflect.Method.invoke(Method.java:372)

Get rid of
<fragment
android:layout_width="match_parent"
android:layout_height="match_parent"
tools:layout="#layout/first_fragment"
class="edu.sjsu.cmpe277.termproject.Fragments.FirstFragment"
android:id="#+id/fragment1"
/>
and use only the explicitly transaction you are using in your Activity. You can't pass a Bundle, declaring a Fragment in the layout, and try to accessing it, is making your app crash

In your activity_second.xml file, change:
class="edu.sjsu.cmpe277.termproject.Fragments.FirstFragment"
to
android:name="edu.sjsu.cmpe277.termproject.Fragments.FirstFragment"
That's the correct prefix to use.

Could not find a method in the activity class android.view.ContextThemeWrapper for onClick handler

I have this problem. I am using two dialog well, one dialog on a dialog, but the second dialog crash when try to search the method. Somebody can help me?
XML: login-email
<TextView
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="#string/forgot_password_email"
android:id="#+id/login_email_tvForgetPassword"
android:layout_marginTop="18dp"
android:layout_gravity="center_horizontal"
android:onClick="openForgetPasswordSend"/>
MainActivity.java
public void openForgetPasswordSend(View view){
FragmentManager fragmentManager = getFragmentManager();
loginforgetpasswordDialogFragment.show(fragmentManager,"Forget Pass");
}
LoginForgetPassword.java
public class LoginForgetPassword extends DialogFragment{
#Override
public Dialog onCreateDialog (Bundle savedInstanceState){
// 1. Instantiate an AlertDialog.Builder with its constructor
AlertDialog.Builder builder = new AlertDialog.Builder(getActivity());
//Get the Layout inflater
//LayoutInflater inflater = getActivity().getLayoutInflater();
LayoutInflater factory = LayoutInflater.from(getActivity());
//Create Dialog
Dialog dialog = new Dialog(getActivity());
//Diable title
dialog.requestWindowFeature(Window.FEATURE_NO_TITLE);
// Inflate and set the layout for the dialog
// Pass null as the parent view because its going in the dialog layout
// builder.setView(inflater.inflate(R.layout.login_register, null));
dialog.setContentView(R.layout.login_forgetpassword);
// Transparency
dialog.getWindow().setBackgroundDrawable(new ColorDrawable(Color.TRANSPARENT));
// 3. Get the AlertDialog from create()
//return builder.create();
return dialog;
}
Error:
java.lang.IllegalStateException: Could not find a method openForgetPasswordSend(View) in the activity class android.view.ContextThemeWrapper for onClick handler on view class android.widget.TextView with id 'login_email_tvForgetPassword'
at android.view.View$1.onClick(View.java:4209)
at android.view.View.performClick(View.java:5156)
at android.view.View$PerformClick.run(View.java:20755)
at android.os.Handler.handleCallback(Handler.java:739)
at android.os.Handler.dispatchMessage(Handler.java:95)
at android.os.Looper.loop(Looper.java:145)
at android.app.ActivityThread.main(ActivityThread.java:5832)
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:1399)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:1194)
Caused by: java.lang.NoSuchMethodException: openForgetPasswordSend [class android.view.View]
at java.lang.Class.getMethod(Class.java:665)
at android.view.View$1.onClick(View.java:4202)
            at android.view.View.performClick(View.java:5156)
            at android.view.View$PerformClick.run(View.java:20755)
            at android.os.Handler.handleCallback(Handler.java:739)
            at android.os.Handler.dispatchMessage(Handler.java:95)
            at android.os.Looper.loop(Looper.java:145)
            at android.app.ActivityThread.main(ActivityThread.java:5832)
            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:1399)
            at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:1194)
I appreciated your help!

I am no expert but, don't set android:onClick="openForgetPasswordSend" It's bad practise to set click events in XML layouts.
Set all click listeners in java. Use your XML, just to setup the views.
The reason for your crash might be that, method you specify in xml has no parameters, but in the class, the method has a parameter of type View.
public void openForgetPasswordSend(View view){...}
Now, I would suggest you try the code below, this should fix your problem :
Remove
android:onClick="openForgetPasswordSend" from the <TextView>
I don't see where you use the layout'login-email.xml'. In that fragment(I assume it's in a fragment), add these lines in :
public class MyFragment extends Fragment {
private TextView myTextView;
#Override
protected void onCreate(Bundle savedInstanceState) {
mytextView = (TextView)findViewById(R.id.login_email_tvForgetPassword);
myTextView.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View view) {
openForgetPasswordSend(view);
}
});
}

NullPointer Exception on setAdapter()

This is my first android app and all i'm trying to do is basically create a list with some sample data. I get the "Unfortunately Sunshine has stopped" error on my phone when i run it.
If i remove this line of code, the app runs -
lstview.setAdapter(mForecastAdapter);
Also When i remove this line of code and run the app i get a calendar of all years but i have not used a calendar anywhere in my code! Any idea why this happens?
Here is my MainActivity.java -
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();
}
}
#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);
}
/**
* A placeholder fragment containing a simple view.
*/
public static class PlaceholderFragment extends Fragment {
private ArrayAdapter<String> mForecastAdapter;
public PlaceholderFragment() {
}
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
View rootView = inflater.inflate(R.layout.fragment_main, container, false);
String[] forecastArray;
forecastArray = new String[]{
"Today - Sunny 88/63",
"Tomorrow - Foggy - 70/40",
"Thursday",
"Friday",
"Saturday",
"Sunday"
};
List<String> weekForecast = new ArrayList<String>(Arrays.asList(forecastArray));
mForecastAdapter = new
ArrayAdapter<String>(
getActivity(),
R.layout.list_item_forecast,
R.id.list_item_forecast_textview,
weekForecast);
ListView lstview = (ListView) rootView.findViewById(R.id.listview_forecast);
lstview.setAdapter(mForecastAdapter);
return rootView;
}
}
}
list_item_forecast.xml -
<?xml version="1.0" encoding="utf-8"?>
<TextView xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:minHeight="?android:attr/listPreferredItemHeight"
android:gravity="center_vertical"
android:id="#+id/list_item_forecast_textview"
>
</TextView>
fragment_main.xml -
<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" 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$PlaceholderFragment">
<ListView
android:layout_width="match_parent"
android:layout_height="match_parent"
android:id="#+id/listview_forecast"></ListView>
</FrameLayout>
AndroidManifest.xml -
<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="com.example.prashanth.sunshine" >
<application
android:allowBackup="true"
android:icon="#mipmap/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.LAUNCHER" />
</intent-filter>
</activity>
</application>
</manifest>
This is a really simple program and i have looked everywhere and none of the solutions seem to work. So -
Why do i get an infinite calendar on my app when i remove this line of code?
lstview.setAdapter(mForecastAdapter);
Why does the app not run with that line?
BTW here is the logcat -
06-17 11:34:32.121 32380-32380/com.example.prashanth.sunshine I/Timeline﹕ Timeline: Activity_idle id: android.os.BinderProxy#1689948 time:428069386
06-17 11:36:28.478 641-641/com.example.prashanth.sunshine D/AndroidRuntime﹕ Shutting down VM
06-17 11:36:28.479 641-641/com.example.prashanth.sunshine E/AndroidRuntime﹕ FATAL EXCEPTION: main
Process: com.example.prashanth.sunshine, PID: 641
java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example.prashanth.sunshine/com.example.prashanth.sunshine.MainActivity}: java.lang.NullPointerException: Attempt to invoke virtual method 'void android.widget.ListView.setAdapter(android.widget.ListAdapter)' on a null object reference
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2354)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2416)
at android.app.ActivityThread.access$900(ActivityThread.java:153)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1319)
at android.os.Handler.dispatchMessage(Handler.java:102)
at android.os.Looper.loop(Looper.java:135)
at android.app.ActivityThread.main(ActivityThread.java:5291)
at java.lang.reflect.Method.invoke(Native Method)
at java.lang.reflect.Method.invoke(Method.java:372)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:931)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:726)
Caused by: java.lang.NullPointerException: Attempt to invoke virtual method 'void android.widget.ListView.setAdapter(android.widget.ListAdapter)' on a null object reference
at com.example.prashanth.sunshine.MainActivity$PlaceholderFragment.onCreateView(MainActivity.java:90)
at android.support.v4.app.Fragment.performCreateView(Fragment.java:1786)
at android.support.v4.app.FragmentManagerImpl.moveToState(FragmentManager.java:953)
at android.support.v4.app.FragmentManagerImpl.moveToState(FragmentManager.java:1136)
at android.support.v4.app.BackStackRecord.run(BackStackRecord.java:739)
at android.support.v4.app.FragmentManagerImpl.execPendingActions(FragmentManager.java:1499)
at android.support.v4.app.FragmentActivity.onStart(FragmentActivity.java:548)
at android.app.Instrumentation.callActivityOnStart(Instrumentation.java:1236)
at android.app.Activity.performStart(Activity.java:6062)
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2317)
            at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2416)
            at android.app.ActivityThread.access$900(ActivityThread.java:153)
            at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1319)
            at android.os.Handler.dispatchMessage(Handler.java:102)
            at android.os.Looper.loop(Looper.java:135)
            at android.app.ActivityThread.main(ActivityThread.java:5291)
            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:931)
            at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:726)
06-17 11:42:14.846 1437-1437/com.example.prashanth.sunshine I/art﹕ Late-enabling -Xcheck:jni
06-17 11:42:15.308 1437-1437/com.example.prashanth.sunshine D/AndroidRuntime﹕ Shutting down VM
06-17 11:42:15.312 1437-1437/com.example.prashanth.sunshine E/AndroidRuntime﹕ FATAL EXCEPTION: main
Process: com.example.prashanth.sunshine, PID: 1437
java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example.prashanth.sunshine/com.example.prashanth.sunshine.MainActivity}: java.lang.NullPointerException: Attempt to invoke virtual method 'void android.widget.ListView.setAdapter(android.widget.ListAdapter)' on a null object reference
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2354)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2416)
at android.app.ActivityThread.access$900(ActivityThread.java:153)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1319)
at android.os.Handler.dispatchMessage(Handler.java:102)
at android.os.Looper.loop(Looper.java:135)
at android.app.ActivityThread.main(ActivityThread.java:5291)
at java.lang.reflect.Method.invoke(Native Method)
at java.lang.reflect.Method.invoke(Method.java:372)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:931)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:726)
Caused by: java.lang.NullPointerException: Attempt to invoke virtual method 'void android.widget.ListView.setAdapter(android.widget.ListAdapter)' on a null object reference
at com.example.prashanth.sunshine.MainActivity$PlaceholderFragment.onCreateView(MainActivity.java:91)
at android.support.v4.app.Fragment.performCreateView(Fragment.java:1786)
at android.support.v4.app.FragmentManagerImpl.moveToState(FragmentManager.java:953)
at android.support.v4.app.FragmentManagerImpl.moveToState(FragmentManager.java:1136)
at android.support.v4.app.BackStackRecord.run(BackStackRecord.java:739)
at android.support.v4.app.FragmentManagerImpl.execPendingActions(FragmentManager.java:1499)
at android.support.v4.app.FragmentActivity.onStart(FragmentActivity.java:548)
at android.app.Instrumentation.callActivityOnStart(Instrumentation.java:1236)
at android.app.Activity.performStart(Activity.java:6062)
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2317)
            at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2416)
            at android.app.ActivityThread.access$900(ActivityThread.java:153)
            at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1319)
            at android.os.Handler.dispatchMessage(Handler.java:102)
            at android.os.Looper.loop(Looper.java:135)
            at android.app.ActivityThread.main(ActivityThread.java:5291)
            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:931)
            at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:726)
06-17 11:51:54.224 2292-2292/com.example.prashanth.sunshine D/AndroidRuntime﹕ Shutting down VM
06-17 11:51:54.225 2292-2292/com.example.prashanth.sunshine E/AndroidRuntime﹕ FATAL EXCEPTION: main
Process: com.example.prashanth.sunshine, PID: 2292
java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example.prashanth.sunshine/com.example.prashanth.sunshine.MainActivity}: java.lang.NullPointerException: Attempt to invoke virtual method 'void android.widget.ListView.setAdapter(android.widget.ListAdapter)' on a null object reference
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2354)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2416)
at android.app.ActivityThread.access$900(ActivityThread.java:153)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1319)
at android.os.Handler.dispatchMessage(Handler.java:102)
at android.os.Looper.loop(Looper.java:135)
at android.app.ActivityThread.main(ActivityThread.java:5291)
at java.lang.reflect.Method.invoke(Native Method)
at java.lang.reflect.Method.invoke(Method.java:372)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:931)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:726)
Caused by: java.lang.NullPointerException: Attempt to invoke virtual method 'void android.widget.ListView.setAdapter(android.widget.ListAdapter)' on a null object reference
at com.example.prashanth.sunshine.MainActivity$PlaceholderFragment.onCreateView(MainActivity.java:91)
at android.support.v4.app.Fragment.performCreateView(Fragment.java:1786)
at android.support.v4.app.FragmentManagerImpl.moveToState(FragmentManager.java:953)
at android.support.v4.app.FragmentManagerImpl.moveToState(FragmentManager.java:1136)
at android.support.v4.app.BackStackRecord.run(BackStackRecord.java:739)
at android.support.v4.app.FragmentManagerImpl.execPendingActions(FragmentManager.java:1499)
at android.support.v4.app.FragmentActivity.onStart(FragmentActivity.java:548)
at android.app.Instrumentation.callActivityOnStart(Instrumentation.java:1236)
at android.app.Activity.performStart(Activity.java:6062)
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2317)
            at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2416)
            at android.app.ActivityThread.access$900(ActivityThread.java:153)
            at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1319)
            at android.os.Handler.dispatchMessage(Handler.java:102)
            at android.os.Looper.loop(Looper.java:135)
            at android.app.ActivityThread.main(ActivityThread.java:5291)
            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:931)
            at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:726)
06-17 11:51:56.581 2292-2292/com.example.prashanth.sunshine I/Process﹕ Sending signal. PID: 2292 SIG: 9
EDIT : Activity_main.xml
<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"
tools:context=".MainActivity" tools:ignore="MergeRootFrame" />
Thanks in Advance!

I changed certain bits of your code, and it seems to be working. I believe it's the problem with wrong imports of AppCompat library. Below is the entire MainActivity code.
import android.app.Fragment;
import android.os.Bundle;
import android.support.v7.app.ActionBarActivity;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.ArrayAdapter;
import android.widget.ListView;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.List;
public class MainActivity extends ActionBarActivity {
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
if (savedInstanceState == null) {
getFragmentManager().beginTransaction()
.add(R.id.container, new PlaceholderFragment())
.commit();
}
}
/**
* A placeholder fragment containing a simple view.
*/
public static class PlaceholderFragment extends Fragment {
private ArrayAdapter<String> mForecastAdapter;
public PlaceholderFragment() {
}
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
View rootView = inflater.inflate(R.layout.fragment_main, container, false);
String[] forecastArray;
forecastArray = new String[]{
"Today - Sunny 88/63",
"Tomorrow - Foggy - 70/40",
"Day After - Life",
"Kidney",
"Saturday",
"Sunday"
};
List<String> weekForecast = new ArrayList<String>(Arrays.asList(forecastArray));
mForecastAdapter = new
ArrayAdapter<String>(
getActivity(),
R.layout.list_item_forecast,
weekForecast);
ListView lstview = (ListView) rootView.findViewById(R.id.listview_forecast);
lstview.setAdapter(mForecastAdapter);
return rootView;
}
}
}
Is this the output you are looking for

Android app crashes after rotating from LANDSCAPE to PORTRAIT

I'm building my first Android app and I've consulted quite some tutorials and stackoverflow posts, but I can't seem to find the proper fix for this problem.
I've been following YouTube tutorials from TheNewBoston and Derek Banas, as well as some written tutorials.
My app runs as it should when starting the app (being in Portrait mode). When I swap it to landscape, it still works fine. However when I rotate it back to portrait, the app crashes with the following error:
04-12 23:42:12.331 28004-28004/nl.avans.mbd2.android.gideon.van.david.multipanefragment E/AndroidRuntime﹕ FATAL EXCEPTION: main
Process: nl.avans.mbd2.android.gideon.van.david.multipanefragment, PID: 28004
java.lang.RuntimeException: Unable to start activity ComponentInfo{nl.avans.mbd2.android.gideon.van.david.multipanefragment/nl.avans.mbd2.android.gideon.van.david.multipanefragment.MainActivity}: android.view.InflateException: Binary XML file line #9: Error inflating class fragment
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2413)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2471)
at android.app.ActivityThread.handleRelaunchActivity(ActivityThread.java:4054)
at android.app.ActivityThread.access$1000(ActivityThread.java:175)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1314)
at android.os.Handler.dispatchMessage(Handler.java:102)
at android.os.Looper.loop(Looper.java:146)
at android.app.ActivityThread.main(ActivityThread.java:5602)
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:1283)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:1099)
at dalvik.system.NativeStart.main(Native Method)
Caused by: android.view.InflateException: Binary XML file line #9: Error inflating class fragment
at android.view.LayoutInflater.createViewFromTag(LayoutInflater.java:719)
at android.view.LayoutInflater.rInflate(LayoutInflater.java:761)
at android.view.LayoutInflater.inflate(LayoutInflater.java:498)
at android.view.LayoutInflater.inflate(LayoutInflater.java:398)
at android.view.LayoutInflater.inflate(LayoutInflater.java:354)
at android.support.v7.app.ActionBarActivityDelegateBase.setContentView(ActionBarActivityDelegateBase.java:240)
at android.support.v7.app.ActionBarActivity.setContentView(ActionBarActivity.java:102)
at nl.avans.mbd2.android.gideon.van.david.multipanefragment.MainActivity.onCreate(MainActivity.java:18)
at android.app.Activity.performCreate(Activity.java:5451)
at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1093)
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2377)
            at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2471)
            at android.app.ActivityThread.handleRelaunchActivity(ActivityThread.java:4054)
            at android.app.ActivityThread.access$1000(ActivityThread.java:175)
            at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1314)
            at android.os.Handler.dispatchMessage(Handler.java:102)
            at android.os.Looper.loop(Looper.java:146)
            at android.app.ActivityThread.main(ActivityThread.java:5602)
            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:1283)
            at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:1099)
            at dalvik.system.NativeStart.main(Native Method)
Caused by: java.lang.IllegalStateException: Fragment nl.avans.mbd2.android.gideon.van.david.multipanefragment.MainPanelFragment did not create a view.
at android.app.Activity.onCreateView(Activity.java:5020)
at android.view.LayoutInflater.createViewFromTag(LayoutInflater.java:695)
            at android.view.LayoutInflater.rInflate(LayoutInflater.java:761)
            at android.view.LayoutInflater.inflate(LayoutInflater.java:498)
            at android.view.LayoutInflater.inflate(LayoutInflater.java:398)
            at android.view.LayoutInflater.inflate(LayoutInflater.java:354)
            at android.support.v7.app.ActionBarActivityDelegateBase.setContentView(ActionBarActivityDelegateBase.java:240)
            at android.support.v7.app.ActionBarActivity.setContentView(ActionBarActivity.java:102)
            at nl.avans.mbd2.android.gideon.van.david.multipanefragment.MainActivity.onCreate(MainActivity.java:18)
            at android.app.Activity.performCreate(Activity.java:5451)
            at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1093)
            at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2377)
            at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2471)
            at android.app.ActivityThread.handleRelaunchActivity(ActivityThread.java:4054)
            at android.app.ActivityThread.access$1000(ActivityThread.java:175)
            at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1314)
            at android.os.Handler.dispatchMessage(Handler.java:102)
            at android.os.Looper.loop(Looper.java:146)
            at android.app.ActivityThread.main(ActivityThread.java:5602)
            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:1283)
            at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:1099)
            at dalvik.system.NativeStart.main(Native Method)
The actual error being:
java.lang.RuntimeException: Unable to start activity ComponentInfo{nl.avans.mbd2.android.gideon.van.david.multipanefragment/nl.avans.mbd2.android.gideon.van.david.multipanefragment.MainActivity}: android.view.InflateException: Binary XML file line #9: Error inflating class fragment
Caused by: android.view.InflateException: Binary XML file line #9: Error inflating class fragment
Caused by: java.lang.IllegalStateException: Fragment nl.avans.mbd2.android.gideon.van.david.multipanefragment.MainPanelFragment did not create a view.
My MainActivity looks like this:
public class MainActivity extends ActionBarActivity {
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
int screenOrientation = getResources().getConfiguration().orientation;
if (screenOrientation == Configuration.ORIENTATION_PORTRAIT) {
hideSidePanel();
}
}
private void hideSidePanel() {
View detailPane = findViewById(R.id.detail_panel);
if(detailPane.getVisibility() == View.VISIBLE) {
detailPane.setVisibility(View.GONE);
}
}
}
MainPanelFragment:
public class MainPanelFragment extends ListFragment {
boolean orientation;
int currentListViewItem;
#Override
public void onActivityCreated(Bundle savedInstanceState) {
super.onActivityCreated(savedInstanceState);
ArrayAdapter<String> connectArrayToListView = new ArrayAdapter<String>(getActivity(), android.R.layout.simple_list_item_activated_1, API.dummyData);
setListAdapter(connectArrayToListView);
orientation = getResources().getConfiguration().orientation == Configuration.ORIENTATION_LANDSCAPE;
if (savedInstanceState != null) {
currentListViewItem = savedInstanceState.getInt("curChoice", 0);
}
if (orientation) {
getListView().setChoiceMode(ListView.CHOICE_MODE_SINGLE);
showDetails(currentListViewItem);
}
}
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
super.onCreateView(inflater, container, savedInstanceState);
return inflater.inflate(R.layout.fragment_main_panel, container, false);
}
#Override
public void onSaveInstanceState(Bundle outState) {
super.onSaveInstanceState(outState);
outState.putInt("curChoice", currentListViewItem);
}
#Override
public void onListItemClick(ListView l, View v, int position, long id) {
showDetails(position);
// super.onListItemClick(l, v, position, id);
}
void showDetails(int kaart) {
currentListViewItem = kaart;
if (orientation) {
getListView().setItemChecked(kaart, true);
DetailPanelFragment details = (DetailPanelFragment) getFragmentManager().findFragmentById(R.id.detail_panel);
if (details == null || details.getShowIndex() == -1) {
details = DetailPanelFragment.newInstance(kaart);
FragmentTransaction ft = getFragmentManager().beginTransaction();
ft.replace(R.id.main_panel, details);
ft.setTransition(FragmentTransaction.TRANSIT_FRAGMENT_FADE);
ft.commit();
}
} else {
Intent intent = new Intent();
intent.setClass(getActivity(), DetailsActivity.class);
intent.putExtra("index", kaart);
startActivity(intent);
}
}
}
activity_main.xml:
<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:animateLayoutChanges="true"
tools:context=".MainActivity">
<fragment
android:layout_width="match_parent"
android:layout_height="match_parent"
android:layout_weight="2"
android:id="#+id/main_panel"
android:layout_alignParentRight="true"
class="nl.avans.mbd2.android.gideon.van.david.multipanefragment.MainPanelFragment"/>
<fragment
android:layout_width="match_parent"
android:layout_height="match_parent"
android:layout_weight="1"
android:id="#+id/detail_panel"
android:layout_alignParentLeft="true"
class="nl.avans.mbd2.android.gideon.van.david.multipanefragment.DetailPanelFragment"/>
</LinearLayout>
fragment_detail_panel.xml:
<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:background="#android:color/holo_blue_bright"
android:layout_gravity="top|center"
android:orientation="vertical">
<TextView
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="Detail panel"
android:textColor="#android:color/white"
android:textStyle="bold"
android:id="#+id/kaartenListViewDetail"
/>
</LinearLayout>
fragment_main_panel.xml:
<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:background="#android:color/holo_red_dark"
android:layout_gravity="top|center"
android:orientation="vertical">
<ListView
android:layout_width="match_parent"
android:layout_height="match_parent"
android:id="#android:id/list">
</ListView>
</LinearLayout>
I also have a folder in /res named layout-land. It contains an activity_main.xml file which is exactly identical to the one posted above.
I've seen similiar questions like this one but it seems that this situation is not (enough) the same to find a valid answer.

android java onClick Could not execute method of the activity

This is my first time working with the recyclerview and I am getting some errors about android:onClick="addItem" here is what I get when I try to add a line of text to my recyclerview. I usually use my phone to test my apps.
java.lang.IllegalStateException: Could not execute method of the activity
at android.view.View$1.onClick(View.java:4012)
at android.view.View.performClick(View.java:4761)
at android.view.View$PerformClick.run(View.java:19767)
at android.os.Handler.handleCallback(Handler.java:739)
at android.os.Handler.dispatchMessage(Handler.java:95)
at android.os.Looper.loop(Looper.java:135)
at android.app.ActivityThread.main(ActivityThread.java:5312)
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:901)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:696)
Caused by: java.lang.reflect.InvocationTargetException
at java.lang.reflect.Method.invoke(Native Method)
at java.lang.reflect.Method.invoke(Method.java:372)
at android.view.View$1.onClick(View.java:4007)
            at android.view.View.performClick(View.java:4761)
            at android.view.View$PerformClick.run(View.java:19767)
            at android.os.Handler.handleCallback(Handler.java:739)
            at android.os.Handler.dispatchMessage(Handler.java:95)
            at android.os.Looper.loop(Looper.java:135)
            at android.app.ActivityThread.main(ActivityThread.java:5312)
            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:901)
            at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:696)
Caused by: java.lang.NullPointerException: Attempt to invoke virtual method 'android.text.Editable android.widget.EditText.getText()' on a null object reference
at com.sapps.app.testapp2.MainActivity.addItem(MainActivity.java:53)
            at java.lang.reflect.Method.invoke(Native Method)
            at java.lang.reflect.Method.invoke(Method.java:372)
            at android.view.View$1.onClick(View.java:4007)
            at android.view.View.performClick(View.java:4761)
            at android.view.View$PerformClick.run(View.java:19767)
            at android.os.Handler.handleCallback(Handler.java:739)
            at android.os.Handler.dispatchMessage(Handler.java:95)
            at android.os.Looper.loop(Looper.java:135)
            at android.app.ActivityThread.main(ActivityThread.java:5312)
            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:901)
            at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:696)
Here is my code where I think is the error, but I don't know exactly:
public class MainActivity extends ActionBarActivity {
private EditText mText;
private RecyclerView.LayoutManager mLayoutManager;
private RecyclerView recyclerView;
private Button btn;
private CustomRecyclerAdapter mAdapter;
private List<Data> mData = new ArrayList<>();
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
// Initializing views.
mText = (EditText) findViewById(R.id.textEt);
recyclerView = (RecyclerView) findViewById(R.id.recycler);
// If the size of views will not change as the data changes.
recyclerView.setHasFixedSize(true);
// Setting the LayoutManager.
mLayoutManager = new LinearLayoutManager(this);
recyclerView.setLayoutManager(mLayoutManager);
// Setting the adapter.
CustomRecyclerAdapter mAdapter = new CustomRecyclerAdapter();
recyclerView.setAdapter(mAdapter);
}
// Called when add button is clicked.
public void addItem(View v) {
if(mText!=null) {
Data dataToAdd = new Data(mText.getText().toString()); mData.add(dataToAdd);
}
}
}
And here is my recyclerview adapter to know for sure:
public class CustomRecyclerAdapter extends RecyclerView.Adapter<RecyclerViewHolder> {
CustomRecyclerAdapter mAdapter;
private List<Data> mData = Collections.emptyList();
public CustomRecyclerAdapter() {
// Pass context or other static stuff that will be needed.
}
public void updateList(List<Data> data) {
mData = data;
notifyDataSetChanged();
}
#Override
public int getItemCount() {
return mData.size();
}
#Override
public RecyclerViewHolder onCreateViewHolder(ViewGroup viewGroup, int position) {
LayoutInflater inflater = LayoutInflater.from(viewGroup.getContext());
View itemView = inflater.inflate(R.layout.list_item, viewGroup, false);
return new RecyclerViewHolder(itemView);
}
#Override
public void onBindViewHolder(RecyclerViewHolder viewHolder, int position) {
viewHolder.title.setText(mData.get(position).text);
}
public void addItemInRec(int position, Data data) {
mData.add(data);
notifyItemInserted(position);
}
public void removeItem(int position) {
mData.remove(position);
notifyItemRemoved(position);
}
}
My MainActivity xml file:
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:orientation="vertical"
android:layout_width="match_parent"
android:layout_height="match_parent"
tools:context=".MainActivity">
<LinearLayout
android:orientation="horizontal"
android:layout_width="match_parent"
android:layout_height="wrap_content">
<EditText
android:id="#+id/textEt"
android:layout_width="0dp"
android:layout_height="wrap_content"
android:layout_weight="1"
android:hint="Text"/>
<Button
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="Add"
android:onClick="addItem"/>
</LinearLayout>
<android.support.v7.widget.RecyclerView
android:id="#+id/recycler"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:scrollbars="vertical"/>
</LinearLayout>
Maybe it is my ViewHolder:
public class RecyclerViewHolder extends RecyclerView.ViewHolder {
public TextView title;
public RecyclerViewHolder(View itemView) {
super(itemView);
title = (TextView) itemView.findViewById(R.id.title);
}
}
Or Data.java class:
public class Data {
public String text;
public Data(String text) {
this.text = text;
}
}

The key is in your error message:
Caused by: java.lang.NullPointerException: Attempt to invoke virtual method 'android.text.Editable android.widget.EditText.getText()' on a null object reference
at com.sapps.app.testapp2.MainActivity.addItem(MainActivity.java:53)
A good tip for learning from your error output is to look at each "Caused by" statement, and scan through the log until you find one of your own files referenced. Then that part of the error log will even tell you what line your code was failing on ( in this case it is line 53 on MainActivity.java).
A Null Pointer Exception in Java is when you attempt to call a method on some object 'A', but that object 'A' is currently null.
So this error message means:
"On line 53 of MainActivity.java, you tried to call a method on some object which doesn't exist yet, so I crashed."
The method that is failing is EditText mText = (EditText) findViewById(R.id.textEt);
Usually this type of failure means that you aren't finding the right ID from your layout. Double check that textEt is the correct ID for this layout element.
EDIT:
Still not sure why your views aren't getting populated, but I did notice an error with your adapter. You are redefining mAdapter, so you have 2 copies, one in local scope and one as a member to MainActivity. This will definitely mess things up.
Right here:
// Setting the adapter.
CustomRecyclerAdapter mAdapter = new CustomRecyclerAdapter();
recyclerView.setAdapter(mAdapter)
You are redefining mAdapter locally. Do this instead:
// Setting the adapter.
mAdapter = new CustomRecyclerAdapter();
recyclerView.setAdapter(mAdapter)

You are getting a null pointer on the getText() call
It means the following line:
EditText mText = (EditText) findViewById(R.id.textEt);
returns null, solution is to check and correct the layout so that textEt is on it.
Edit:
If you are sure that it's in the layout remove EditText declaration.
Declare as private EditText mText; on the class scope
setContentView(R.layout.name_of_layout_here);
mText = (EditText) findViewById(R.id.textEt);

The view in addItem(View v) is referring to the button only.
The EditText object that you want is not in the button, it is in the button's parent view.
If you try to access the object from the button view it will be null, because the button does not have it.
Instead you need to access the object from the button's parent view.
// Solution:
public void addItem(View v) {
View parentView = (View) v.getParent();
EditText mText = (EditText) parentView.findViewById(R.id.textEt);
Log.d("LOG", mText.getText().toString()));
}
I know that technically this does not solve the code in the question. But the code in the question has been changed from what produced the error so this would solve the original buggy code that actually produced the question.
I am guessing that the original buggy code looked like this:
// My guess this was the original buggy code
// MainActivity.java
public void addItem(View v) {
EditText mText = (EditText) v.findViewById(R.id.textEt);
Data dataToAdd = new Data(mText.getText().toString());
mData.add(dataToAdd);
}
// MainActivity.xml
<LinearLayout>
<EditText
android:id="#+id/textEt"
/>
<Button
android:text="Add"
android:onClick="addItem"/>
</LinearLayout>

Change public void addItemInRec to public void addItem. There is no method for onClick in mainActivity.