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Showing error while adding 4 menu (items) in BottomNavigationView

I am new to android .. trying to build application that is having webview inside fragment and in the bottom it is having BottomNavigationView on click of particular item fragment change according to click .
every thing is working fine when having 3 items in BottomNavigationView when i add 4 app start crashing .
error is as fallows -
E/AndroidRuntime: FATAL EXCEPTION: main
Process: in.xparticle.digitalkabadi, PID: 23369
java.lang.RuntimeException: Unable to start activity ComponentInfo{in.xparticle.digitalkabadi/in.xparticle.digitalkabadi.MainActivity}: android.view.InflateException: Binary XML file line #19 in in.xparticle.digitalkabadi:layout/activity_main: Binary XML file line #19 in in.xparticle.digitalkabadi:layout/activity_main: Error inflating class com.google.android.material.bottomnavigation.BottomNavigationView
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:3270)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:3409)
at android.app.servertransaction.LaunchActivityItem.execute(LaunchActivityItem.java:83)
at android.app.servertransaction.TransactionExecutor.executeCallbacks(TransactionExecutor.java:135)
at android.app.servertransaction.TransactionExecutor.execute(TransactionExecutor.java:95)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:2016)
at android.os.Handler.dispatchMessage(Handler.java:107)
at android.os.Looper.loop(Looper.java:214)
at android.app.ActivityThread.main(ActivityThread.java:7356)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:491)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:940)
Caused by: android.view.InflateException: Binary XML file line #19 in in.xparticle.digitalkabadi:layout/activity_main: Binary XML file line #19 in in.xparticle.digitalkabadi:layout/activity_main: Error inflating class com.google.android.material.bottomnavigation.BottomNavigationView
Caused by: android.view.InflateException: Binary XML file line #19 in in.xparticle.digitalkabadi:layout/activity_main: Error inflating class com.google.android.material.bottomnavigation.BottomNavigationView
Caused by: java.lang.reflect.InvocationTargetException
at java.lang.reflect.Constructor.newInstance0(Native Method)
at java.lang.reflect.Constructor.newInstance(Constructor.java:343)
at android.view.LayoutInflater.createView(LayoutInflater.java:854)
at android.view.LayoutInflater.createViewFromTag(LayoutInflater.java:1006)
at android.view.LayoutInflater.createViewFromTag(LayoutInflater.java:961)
at android.view.LayoutInflater.rInflate(LayoutInflater.java:1123)
at android.view.LayoutInflater.rInflateChildren(LayoutInflater.java:1084)
at android.view.LayoutInflater.inflate(LayoutInflater.java:682)
at android.view.LayoutInflater.inflate(LayoutInflater.java:534)
at android.view.LayoutInflater.inflate(LayoutInflater.java:481)
at androidx.appcompat.app.AppCompatDelegateImpl.setContentView(AppCompatDelegateImpl.java:696)
at androidx.appcompat.app.AppCompatActivity.setContentView(AppCompatActivity.java:170)
at in.xparticle.digitalkabadi.MainActivity.onCreate(MainActivity.java:17)
at android.app.Activity.performCreate(Activity.java:7824)
at android.app.Activity.performCreate(Activity.java:7813)
at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1306)
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:3245)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:3409)
at android.app.servertransaction.LaunchActivityItem.execute(LaunchActivityItem.java:83)
at android.app.servertransaction.TransactionExecutor.executeCallbacks(TransactionExecutor.java:135)
at android.app.servertransaction.TransactionExecutor.execute(TransactionExecutor.java:95)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:2016)
at android.os.Handler.dispatchMessage(Handler.java:107)
at android.os.Looper.loop(Looper.java:214)
at android.app.ActivityThread.main(ActivityThread.java:7356)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:491)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:940)
E/AndroidRuntime: Caused by: java.lang.NullPointerException: Attempt to invoke virtual method 'void android.view.View.setImportantForAccessibility(int)' on a null object reference
at androidx.core.view.ViewCompat.setImportantForAccessibility(ViewCompat.java:1119)
at com.google.android.material.bottomnavigation.BottomNavigationItemView.<init>(BottomNavigationItemView.java:104)
at com.google.android.material.bottomnavigation.BottomNavigationItemView.<init>(BottomNavigationItemView.java:87)
at com.google.android.material.bottomnavigation.BottomNavigationItemView.<init>(BottomNavigationItemView.java:83)
at com.google.android.material.bottomnavigation.BottomNavigationMenuView.getNewItem(BottomNavigationMenuView.java:606)
at com.google.android.material.bottomnavigation.BottomNavigationMenuView.buildMenuView(BottomNavigationMenuView.java:538)
at com.google.android.material.bottomnavigation.BottomNavigationPresenter.updateMenuView(BottomNavigationPresenter.java:67)
at com.google.android.material.bottomnavigation.BottomNavigationView.inflateMenu(BottomNavigationView.java:344)
at com.google.android.material.bottomnavigation.BottomNavigationView.<init>(BottomNavigationView.java:226)
at com.google.android.material.bottomnavigation.BottomNavigationView.<init>(BottomNavigationView.java:133)
... 28 more
MainActivity.java
public class MainActivity extends AppCompatActivity {
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
BottomNavigationView bottomNav = findViewById(R.id.bottom_navigation);
bottomNav.setOnNavigationItemSelectedListener(navListener);
getSupportFragmentManager().beginTransaction().replace(R.id.fragment_container,
new HomeFragment()).commit();
}
private BottomNavigationView.OnNavigationItemSelectedListener navListener =
new BottomNavigationView.OnNavigationItemSelectedListener() {
#Override
public boolean onNavigationItemSelected(#NonNull MenuItem item) {
Fragment selectedFragment = null;
switch (item.getItemId()){
case R.id.nav_home:
selectedFragment = new HomeFragment();
break;
case R.id.nav_scrape_price:
selectedFragment = new ScrapePriceFragment();
break;
case R.id.nav_aboutUs:
selectedFragment = new AboutUsFragment();
break;
case R.id.nav_scrape_Process:
selectedFragment = new AboutUsFragment();
break;
}
assert selectedFragment != null;
getSupportFragmentManager().beginTransaction().replace(R.id.fragment_container,
selectedFragment).commit();
return true;
}
};
}

try this -->
public class MainActivity extends AppCompatActivity implements BottomNavigationView.OnNavigationItemSelectedListener {
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
//loading the default fragment
loadFragment(new FirstFragment());
//getting bottom navigation view and attaching the listener
BottomNavigationView navigation = findViewById(R.id.bottom_navigation);
navigation.setOnNavigationItemSelectedListener(this);
}
#Override
public boolean onNavigationItemSelected(#NonNull MenuItem item) {
Fragment fragment = null;
switch (item.getItemId()) {
case R.id.id1:
fragment = new FirstFragment();
break;
case R.id.id2:
fragment = new SecondFragment();
break;
case R.id.id3:
fragment = new thirsFragment();
break;
case R.id.id4:
fragment = new fourthFragment();
break;
}
return loadFragment(fragment);
}
private boolean loadFragment(Fragment fragment) {
//switching fragment
if (fragment != null) {
getSupportFragmentManager()
.beginTransaction()
.replace(R.id.fragment_container, fragment)
.commit();
return true;
}
return false;
}
}

MPAndroidChart keeps throwing null error

I'm just trying this library out to see if it fits my needs and so far I have not been able to get it to work. Here is the code
package com.example.user.bottomnavigationbar;
import android.content.DialogInterface;
import android.content.Intent;
import android.os.Bundle;
import android.support.annotation.NonNull;
import android.support.design.widget.BottomNavigationView;
import android.support.v7.app.AlertDialog;
import android.support.v7.app.AppCompatActivity;
import android.view.MenuItem;
import com.github.mikephil.charting.charts.PieChart;
import com.github.mikephil.charting.data.PieData;
import com.github.mikephil.charting.data.PieDataSet;
import com.github.mikephil.charting.data.PieEntry;
import java.util.ArrayList;
public class MainActivity extends AppCompatActivity {
PieChart pc;
private BottomNavigationView.OnNavigationItemSelectedListener mOnNavigationItemSelectedListener
= new BottomNavigationView.OnNavigationItemSelectedListener() {
#Override
public boolean onNavigationItemSelected(#NonNull MenuItem item) {
switch (item.getItemId()) {
case R.id.navigation_home:
return true;
// case R.id.navigation_overview:
// Intent intentOverview = new Intent(MainActivity.this, activity_test.class);
// intentOverview.setFlags(Intent.FLAG_ACTIVITY_NEW_TASK | Intent.FLAG_ACTIVITY_CLEAR_TASK);
// MainActivity.this.finish();
// startActivity(intentOverview);
// return true;
case R.id.navigation_expenses:
return true;
case R.id.navigation_reminder:
return true;
case R.id.navigation_income:
return true;
case R.id.navigation_login:
Intent intentLogin = new Intent(MainActivity.this, LoginActivity.class);
intentLogin.setFlags(Intent.FLAG_ACTIVITY_NEW_TASK | Intent.FLAG_ACTIVITY_CLEAR_TASK);
MainActivity.this.finish();
startActivity(intentLogin);
return true;
}
return false;
}
};
#Override
protected void onCreate(Bundle savedInstanceState)
{
pc = findViewById(R.id.chart);
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
BottomNavigationView navigation = findViewById(R.id.navigation);
navigation.setOnNavigationItemSelectedListener(mOnNavigationItemSelectedListener);
ArrayList <PieEntry> pieData = new ArrayList<>();
pieData.add(new PieEntry(10));
pieData.add(new PieEntry(20));
pieData.add(new PieEntry(30));
PieDataSet dataSet = new PieDataSet(pieData, "Survey Results");
PieData data = new PieData(dataSet);
pc.setData(data);
}
public void onBackPressed()
{
new AlertDialog.Builder(this)
.setIcon(android.R.drawable.ic_dialog_alert)
.setTitle("Closing Activity")
.setMessage("Are you sure you want to close this activity?")
.setPositiveButton("Yes", new DialogInterface.OnClickListener()
{
#Override
public void onClick(DialogInterface dialog, int which) {
finish();
}
})
.setNegativeButton("No", null)
.show();
}
}
And here is the error I get
E/AndroidRuntime: FATAL EXCEPTION: main
Process: com.example.user.bottomnavigationbar, PID: 4172
java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example.user.bottomnavigationbar/com.example.user.bottomnavigationbar.MainActivity}: java.lang.NullPointerException: Attempt to invoke virtual method 'void com.github.mikephil.charting.charts.PieChart.setData(com.github.mikephil.charting.data.ChartData)' on a null object reference
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2325)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2387)
at android.app.ActivityThread.access$800(ActivityThread.java:151)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1303)
at android.os.Handler.dispatchMessage(Handler.java:102)
at android.os.Looper.loop(Looper.java:135)
at android.app.ActivityThread.main(ActivityThread.java:5254)
at java.lang.reflect.Method.invoke(Native Method)
at java.lang.reflect.Method.invoke(Method.java:372)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:903)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:698)
Caused by: java.lang.NullPointerException: Attempt to invoke virtual method 'void com.github.mikephil.charting.charts.PieChart.setData(com.github.mikephil.charting.data.ChartData)' on a null object reference
at com.example.user.bottomnavigationbar.MainActivity.onCreate(MainActivity.java:78)
at android.app.Activity.performCreate(Activity.java:5990)
at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1106)
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2278)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2387) 
at android.app.ActivityThread.access$800(ActivityThread.java:151) 
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1303) 
at android.os.Handler.dispatchMessage(Handler.java:102) 
at android.os.Looper.loop(Looper.java:135) 
at android.app.ActivityThread.main(ActivityThread.java:5254) 
at java.lang.reflect.Method.invoke(Native Method) 
at java.lang.reflect.Method.invoke(Method.java:372) 
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:903) 
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:698)
I've searched for a bit and all I've found was that for others, they did not initialize the object hence it throws this error. Now someone did mention that it is possible to create the chart in code and then add it to the activity as the documentation's Getting Started page suggests but I have been unable to get it working. So what gives?
P.S Left in the code for navigation as I'm not sure if it might be the cause of the issue

You are first finding the view and then providing the content view to your activity replace with this code
#Override
protected void onCreate(Bundle savedInstanceState)
{
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
pc = findViewById(R.id.chart);
BottomNavigationView navigation = findViewById(R.id.navigation);
navigation.setOnNavigationItemSelectedListener(mOnNavigationItemSelectedListener);
ArrayList <PieEntry> pieData = new ArrayList<>();
pieData.add(new PieEntry(10));
pieData.add(new PieEntry(20));
pieData.add(new PieEntry(30));
PieDataSet dataSet = new PieDataSet(pieData, "Survey Results");
PieData data = new PieData(dataSet);
pc.setData(data);
}

Getting NullPointerException in SharedPreferences [duplicate]

This question already has answers here:
What is a NullPointerException, and how do I fix it?
(12 answers)
Closed 5 years ago.
I start android developing recently. I may have some lack of knowledge in this scenario.But I searched a lot and can't make a solution for this project.
Facing problem with this.I failed to figure it out. My SharedPreferences Class is.
public class PermanentScoreHolder {
public static boolean storeScore(String prefName,float score)
{
float temp = VarHolder.SHARED_PREFERENCES.getFloat(VarHolder.SUFFIX_PREFERENCES+prefName, 0f);
if(temp<score)
{
VarHolder.EDITOR.putFloat(VarHolder.SUFFIX_PREFERENCES+prefName, score);
VarHolder.EDITOR.commit();
return true;
}
return false;
}
public static float getScore(String prefName)
{
return VarHolder.SHARED_PREFERENCES.getFloat(VarHolder.SUFFIX_PREFERENCES+prefName, 0f);
}
}
My activity class is like this:
public class ScoreActivity extends Activity {
TextView normal,danger,thunder,zen,rush;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
//this.requestWindowFeature(Window.FEATURE_NO_TITLE);
this.getWindow().setFlags(WindowManager.LayoutParams.FLAG_FULLSCREEN,
WindowManager.LayoutParams.FLAG_FULLSCREEN);
this.requestWindowFeature(Window.FEATURE_NO_TITLE);
setContentView(R.layout.activity_score);
normal = (TextView) findViewById(R.id.normalScore);
normal.setText(PermanentScoreHolder.getScore("1")+"");//Logcat says problem is here.
}
public void onBackPressed() {
Intent i = new Intent(getBaseContext(),OptionMenuActivity.class);
startActivity(i);
finish();
};
#Override
public boolean onCreateOptionsMenu(Menu menu) {
// Inflate the menu; this adds items to the action bar if it is present.
getMenuInflater().inflate(R.menu.score, menu);
return true;
}
#Override
public boolean onOptionsItemSelected(MenuItem item) {
// Handle action bar item clicks here. The action bar will
// automatically handle clicks on the Home/Up button, so long
// as you specify a parent activity in AndroidManifest.xml.
int id = item.getItemId();
if (id == R.id.action_settings) {
return true;
}
return super.onOptionsItemSelected(item);
}
#Override
protected void onPause() {
super.onResume();
overridePendingTransition(0, 0);
}
#Override
protected void onResume() {
super.onResume();
overridePendingTransition(0, 0);
}}
My Logcat is here:
FATAL EXCEPTION: main
Process: cafesoft.td.tappingtile, PID: 8740
java.lang.RuntimeException: Unable to start activity ComponentInfo{cafesoft.td.tappingtile/cafesoft.td.tappingtile.ScoreActivity}: java.lang.NullPointerException: Attempt to invoke interface method 'float android.content.SharedPreferences.getFloat(java.lang.String, float)' on a null object reference
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$H.handleMessage(ActivityThread.java:1593)
at android.os.Handler.dispatchMessage(Handler.java:105)
at android.os.Looper.loop(Looper.java:164)
at android.app.ActivityThread.main(ActivityThread.java:6540)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.Zygote$MethodAndArgsCaller.run(Zygote.java:240)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:767)
Caused by: java.lang.NullPointerException: Attempt to invoke interface method 'float android.content.SharedPreferences.getFloat(java.lang.String, float)' on a null object reference
at cafesoft.td.tappingtile.PermanentScoreHolder.getScore(PermanentScoreHolder.java:18)
at cafesoft.td.tappingtile.ScoreActivity.onCreate(ScoreActivity.java:98)
at android.app.Activity.performCreate(Activity.java:6980)
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$H.handleMessage(ActivityThread.java:1593) 
at android.os.Handler.dispatchMessage(Handler.java:105) 
at android.os.Looper.loop(Looper.java:164) 
at android.app.ActivityThread.main(ActivityThread.java:6540) 
at java.lang.reflect.Method.invoke(Native Method) 
at com.android.internal.os.Zygote$MethodAndArgsCaller.run(Zygote.java:240) 
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:767)
I don't understand whats wrong with this code.I need a solution and why this occurs.  

Your VarHolder.SHARED_PREFERENCES in the class PermanentScoreHolder has a null reference.
This is how we get SharedPreferences instance:
SharedPreferences pref = context.getSharedPreferences("unique_key", Context.MODE_PRIVATE);
Then get the float from SharedPreferences:
pref.getFloat("key", defaultValue);

RecyclerView's onClick method crashes the app

Below is my MainActivity.java (I have removed some of unnecessary code. My main activity was a Navigation Viewer activity)
public class MainActivity extends AppCompatActivity
implements NavigationView.OnNavigationItemSelectedListener {
RecyclerView recyclerView;
RecyclerView.Adapter adapter;
RecyclerView.LayoutManager layoutManager;
ArrayList<MainStoryTile> list = new ArrayList<MainStoryTile>();
int[] image_id = { R.drawable.sample, R.drawable.sample, R.drawable.sample};
String[] name, email, mobile;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
name = getResources().getStringArray(R.array.person_name);
email = getResources().getStringArray(R.array.person_email);
mobile = getResources().getStringArray(R.array.person_mobile);
int count = 0;
for(String NAME: name){
MainStoryTile contact = new MainStoryTile(image_id[count], NAME, email[count], mobile[count]);
count++;
list.add(contact);
}
recyclerView = (RecyclerView) findViewById(R.id.recycler_view);
layoutManager = new LinearLayoutManager(this);
recyclerView.setLayoutManager(layoutManager);
recyclerView.setHasFixedSize(true);
adapter = new MainStoryAdapter(list);
recyclerView.setAdapter(adapter);
}
#Override
public void onBackPressed() {
}
#Override
public boolean onCreateOptionsMenu(Menu menu) {
}
#Override
public boolean onOptionsItemSelected(MenuItem item) {
}
#SuppressWarnings("StatementWithEmptyBody")
#Override
public boolean onNavigationItemSelected(MenuItem item) {
return true;
}
}
Below is my Adapter class. (Note : there is an inner class)
public class MainStoryAdapter extends RecyclerView.Adapter<MainStoryAdapter.StoryViewHolder>{
ArrayList<MainStoryTile> contacts = new ArrayList<MainStoryTile>();
public MainStoryAdapter(ArrayList<MainStoryTile> contacts){
this.contacts = contacts;
}
#Override
public StoryViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
View view = LayoutInflater.from(parent.getContext()).inflate(R.layout.content_main,parent,false );
StoryViewHolder storyViewHolder = new StoryViewHolder(view);
return storyViewHolder;
}
#Override
public void onBindViewHolder(StoryViewHolder holder, int position) {
MainStoryTile CON = contacts.get(position);
holder.person_img.setImageResource(CON.getImage_id());
holder.person_name.setText(CON.getName());
holder.person_email.setText(CON.getEmail());
holder.person_mobile.setText(CON.getMobile());
}
#Override
public int getItemCount() {
return contacts.size();
}
public static class StoryViewHolder extends RecyclerView.ViewHolder implements View.OnClickListener{
ImageView person_img;
TextView person_name, person_email, person_mobile;
public StoryViewHolder(View view){
super(view);
person_img = (ImageView) view.findViewById(R.id.person_image);
person_name = (TextView) view.findViewById(R.id.person_name);
person_email = (TextView) view.findViewById(R.id.person_email);
person_mobile = (TextView) view.findViewById(R.id.person_mobile);
view.setOnClickListener(this);
}
#Override
public void onClick(View v) {
Log.d("MY LOG", "sdurfhiusrhdidysdysdysdysdys r");
}
}
}
When I click on a item, my app crashes. below is error log :
03-17 15:20:38.638 28744-28744/com.storyteller.pro.storyteller E/AndroidRuntime: FATAL EXCEPTION: main
Process: com.storyteller.pro.storyteller, PID: 28744
java.lang.IllegalStateException: Could not execute method of the activity
at android.view.View$1.onClick(View.java:4286)
at android.view.View.performClick(View.java:5242)
at android.view.View$PerformClick.run(View.java:21196)
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:6938)
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:1404)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:1199)
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$1.onClick(View.java:4281)
at android.view.View.performClick(View.java:5242)
at android.view.View$PerformClick.run(View.java:21196)
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:6938)
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:1404)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:1199)
Caused by: java.lang.IllegalStateException: The specified child already has a parent. You must call removeView() on the child's parent first.
at android.view.ViewGroup.addViewInner(ViewGroup.java:4277)
at android.view.ViewGroup.addView(ViewGroup.java:4127)
at android.view.ViewGroup.addView(ViewGroup.java:4068)
at android.view.ViewGroup.addView(ViewGroup.java:4041)
at android.support.v7.app.AppCompatDelegateImplV7.setContentView(AppCompatDelegateImplV7.java:247)
at android.support.v7.app.AppCompatActivity.setContentView(AppCompatActivity.java:114)
at java.lang.reflect.Method.invoke(Native Method)
at java.lang.reflect.Method.invoke(Method.java:372)
at android.view.View$1.onClick(View.java:4281)
at android.view.View.performClick(View.java:5242)
at android.view.View$PerformClick.run(View.java:21196)
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:6938)
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:1404)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:1199)
03-17 15:20:43.048 28744-28744/com.storyteller.pro.storyteller I/Process: Sending signal. PID: 28744 SIG: 9
Update: Even after I commented the following line in the view.setOnClickListener(this); in the MainStoryAdapter, my app still crashing when I click on an item.
Below is the project for those who like to see more > project zip version

I checked your project and you, why ever, define android:onClick="setContentView" in your content_main.xml layout for the CardView.
Remove that attribute and it works.

I have simple android App in android studio and it does not work

package viewbrosers.mehdi.home.mytestappviewbrowser;
import android.app.Activity;
import android.content.Context;
import android.content.DialogInterface;
import android.content.Intent;
import android.os.Bundle;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.Toast;
import java.util.Random;
public class MainActivity extends Activity {
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
Button getAnswer = (Button) findViewById(R.id.getAnswerButton);
getAnswer.setOnClickListener(getAnswerListener);
}
private View.OnClickListener getAnswerListener = new View.OnClickListener() {
#Override
public void onClick(View v) {
Random randomnum = new Random();
int numToast = randomnum.nextInt(19);
numToast++;
CharSequence text = "";
switch (numToast) {
case 1:
text = getString(R.string.answer1);
break;
case 2:
text = getString(R.string.answer2);
break;
case 3:
text = getString(R.string.answer3);
break;
case 4:
text = getString(R.string.answer4);
break;
case 5:
text = getString(R.string.answer5);
break;
case 6:
text = getString(R.string.answer6);
break;
case 7:
text = getString(R.string.answer7);
break;
}
Context context = getApplicationContext();
int duration = Toast.LENGTH_LONG;
Toast toast = Toast.makeText(context, text, duration);
toast.show();
}
};
#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);
}
}
My error is:
Unfortunately Application has stopped and 06-05
11:31:44.131 13711-13711/? I/art﹕ Not late-enabling -Xcheck:jni
(already on) 06-05 11:31:44.208 13711-13711/? D/AndroidRuntime﹕
Shutting down VM 06-05 11:31:44.208 13711-13711/? E/AndroidRuntime﹕
FATAL EXCEPTION: main
Process: viewbrosers.mehdi.home.mytestappviewbrowser, PID: 13711
java.lang.RuntimeException: Unable to start activity ComponentInfo{viewbrosers.mehdi.home.mytestappviewbrowser/viewbrosers.mehdi.home.mytestappviewbrowser.MainActivity}:
java.lang.NullPointerException: Attempt to invoke virtual method
'boolean java.lang.String.equals(java.lang.Object)' on a null object
reference
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2325)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2390)
at android.app.ActivityThread.access$800(ActivityThread.java:151)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1303)
at android.os.Handler.dispatchMessage(Handler.java:102)
at android.os.Looper.loop(Looper.java:135)
at android.app.ActivityThread.main(ActivityThread.java:5257)
at java.lang.reflect.Method.invoke(Native Method)
at java.lang.reflect.Method.invoke(Method.java:372)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:903)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:698)
Caused by: java.lang.NullPointerException: Attempt to invoke virtual method 'boolean java.lang.String.equals(java.lang.Object)' on
a null object reference
at android.view.LayoutInflater.createViewFromTag(LayoutInflater.java:715)
at android.view.LayoutInflater.rInflate(LayoutInflater.java:806)
at android.view.LayoutInflater.inflate(LayoutInflater.java:504)
at android.view.LayoutInflater.inflate(LayoutInflater.java:414)
at android.view.LayoutInflater.inflate(LayoutInflater.java:365)
at com.android.internal.policy.impl.PhoneWindow.setContentView(PhoneWindow.java:378)
at android.app.Activity.setContentView(Activity.java:2145)
at viewbrosers.mehdi.home.mytestappviewbrowser.MainActivity.onCreate(MainActivity.java:23)
at android.app.Activity.performCreate(Activity.java:5990)
at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1106)
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2278)
            at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2390)
            at android.app.ActivityThread.access$800(ActivityThread.java:151)
            at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1303)
            at android.os.Handler.dispatchMessage(Handler.java:102)
            at android.os.Looper.loop(Looper.java:135)
            at android.app.ActivityThread.main(ActivityThread.java:5257)
            at java.lang.reflect.Method.invoke(Native Method)
            at java.lang.reflect.Method.invoke(Method.java:372)
            at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:903)
            at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:698) 06-05
11:31:44.218 13711-13718/? I/art﹕ Debugger is no longer active 06-05
11:32:28.690 13711-13718/viewbrosers.mehdi.home.mytestappviewbrowser
W/art﹕ Suspending all threads took: 12.748ms

Move the creation and initialization of your text variable outside of the onClick() method. Try the following code.
public class MainActivity extends Activity {
CharSequence text;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
text = "";
Button getAnswer = (Button) findViewById(R.id.getAnswerButton);
getAnswer.setOnClickListener(getAnswerListener);
}
private View.OnClickListener getAnswerListener = new View.OnClickListener() {
#Override
public void onClick(View v) {
Random randomnum = new Random();
int numToast = randomnum.nextInt(19);
numToast++;
switch (numToast) {
case 1:
text = getString(R.string.answer1);
break;
case 2:
text = getString(R.string.answer2);
break;
case 3:
text = getString(R.string.answer3);
break;
case 4:
text = getString(R.string.answer4);
break;
case 5:
text = getString(R.string.answer5);
break;
case 6:
text = getString(R.string.answer6);
break;
case 7:
text = getString(R.string.answer7);
break;
}
Context context = getApplicationContext();
int duration = Toast.LENGTH_LONG;
Toast toast = Toast.makeText(context, text, duration);
toast.show();
}
};
#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);
}
}

You are somewhere using equals function on string which is null.
Look at exception: 'boolean java.lang.String.equals(java.lang.Object)' on a null object
reference

Try it, may be like this.
public class MainActivity extends Activity implements OnClickListener
{
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
Button getAnswer = (Button) findViewById(R.id.getAnswerButton);
getAnswer.setOnClickListener(this);
}
#Override
public void onClick(View v) {
switch (v.getId())
{
case R.id.getAnswerButton:
//Your code
break;
}
}
}