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Android OnClick and OnclickListner

I am new to android development. My current application crashes on onClick event from the XML, but it seems to work just fine with onClickListner.
public static String URL_WEB;
NsdUtils mNsdUtils;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
final NsdUtils mNsdUtils = new NsdUtils(this);
mNsdUtils.initializeNsd();
/*Button button =(Button) findViewById(R.id.btn_discover_networks);
button.setOnClickListener(new View.OnClickListener(){
public void onClick(View view)
{
mNsdUtils.discoverServices();
}
});*/
}
public void onClickDiscover(View view){
mNsdUtils.discoverServices();
}
Logs:
E/AndroidRuntime: FATAL EXCEPTION: main
Process: com.example.android.implicitintents, PID: 6397
java.lang.IllegalStateException: Could not execute method for android:onClick
at android.support.v7.app.AppCompatViewInflater$DeclaredOnClickListener.onClick(AppCompatViewInflater.java:293)
at android.view.View.performClick(View.java:5637)
at android.view.View$PerformClick.run(View.java:22429)
at android.os.Handler.handleCallback(Handler.java:751)
at android.os.Handler.dispatchMessage(Handler.java:95)
at android.os.Looper.loop(Looper.java:154)
at android.app.ActivityThread.main(ActivityThread.java:6119)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:886)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:776)
Caused by: java.lang.reflect.InvocationTargetException
at java.lang.reflect.Method.invoke(Native Method)
at android.support.v7.app.AppCompatViewInflater$DeclaredOnClickListener.onClick(AppCompatViewInflater.java:288)
at android.view.View.performClick(View.java:5637) 
at android.view.View$PerformClick.run(View.java:22429) 
at android.os.Handler.handleCallback(Handler.java:751) 
at android.os.Handler.dispatchMessage(Handler.java:95) 
at android.os.Looper.loop(Looper.java:154) 
at android.app.ActivityThread.main(ActivityThread.java:6119) 
at java.lang.reflect.Method.invoke(Native Method) 
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:886) 
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:776) 
Caused by: java.lang.NullPointerException: Attempt to invoke virtual method 'void com.example.android.implicitintents.Utils.NsdUtils.discoverServices()' on a null object reference
at com.example.android.implicitintents.MainActivity.onClickDiscoverAura(MainActivity.java:40)
at java.lang.reflect.Method.invoke(Native Method) 
at android.support.v7.app.AppCompatViewInflater$DeclaredOnClickListener.onClick(AppCompatViewInflater.java:288) 
at android.view.View.performClick(View.java:5637) 
at android.view.View$PerformClick.run(View.java:22429) 
at android.os.Handler.handleCallback(Handler.java:751) 
at android.os.Handler.dispatchMessage(Handler.java:95) 
at android.os.Looper.loop(Looper.java:154) 
at android.app.ActivityThread.main(ActivityThread.java:6119) 
at java.lang.reflect.Method.invoke(Native Method) 
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:886) 
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:776) 
It seems I am missing a very basic detail. Any help will be great.
NsdUtils
public class NsdUtils {
Context mContext;
NsdManager mNsdManager;
NsdManager.ResolveListener mResolveListener;
NsdManager.DiscoveryListener mDiscoveryListener;
//To find all the available networks SERVICE_TYPE = "_services._dns-sd._udp"
public static final String SERVICE_TYPE = "_http._tcp";
public static final String TAG = "NsdUtils";
public String mServiceName = "_hap";
NsdServiceInfo mService;
public NsdUtils(Context context) {
mContext = context;
mNsdManager = (NsdManager) context.getSystemService(Context.NSD_SERVICE);
}
public void initializeNsd() {
initializeDiscoveryListener();
initializeResolveListener();
}
public void initializeDiscoveryListener() {
mDiscoveryListener = new NsdManager.DiscoveryListener() {
#Override
public void onDiscoveryStarted(String regType) {
Log.d(TAG, "Service discovery started " + regType);
}
#Override
public void onServiceFound(NsdServiceInfo service) {
Log.d(TAG, "Service discovery success" + service);
if(!service.getServiceType().equals(SERVICE_TYPE)){
Log.d(TAG, "Unknown Service Type: " + service.getServiceType());
}
else if(service.getServiceName().equals(mServiceName)){
Log.d(TAG, "Same Machine: " + mServiceName);
}
else if(service.getServiceName().contains(mServiceName)){
mNsdManager.resolveService(service, mResolveListener);
}
}
#Override
public void onServiceLost(NsdServiceInfo service) {
Log.e(TAG, "service lost" + service);
if (mService == service) {
mService = null;
}
}
#Override
public void onDiscoveryStopped(String serviceType) {
Log.i(TAG, "Discovery stopped: " + serviceType);
}
#Override
public void onStartDiscoveryFailed(String serviceType, int errorCode) {
Log.e(TAG, "Discovery failed: Error code:" + errorCode);
mNsdManager.stopServiceDiscovery(this);
}
#Override
public void onStopDiscoveryFailed(String serviceType, int errorCode) {
Log.e(TAG, "Discovery failed: Error code:" + errorCode);
mNsdManager.stopServiceDiscovery(this);
}
};
}
public void initializeResolveListener() {
mResolveListener = new NsdManager.ResolveListener() {
#Override
public void onResolveFailed(NsdServiceInfo serviceInfo, int errorCode) {
Log.e(TAG, "Resolve failed" + errorCode);
}
#Override
public void onServiceResolved(NsdServiceInfo serviceInfo) {
Log.e(TAG, "Resolve Succeeded. " + serviceInfo);
if (serviceInfo.getServiceName().equals(mServiceName)) {
Log.d(TAG, "Same IP.");
return;
}
mService = serviceInfo;
}
};
}
public void stopDiscovery() {
mNsdManager.stopServiceDiscovery(mDiscoveryListener);
}
public NsdServiceInfo getChosenServiceInfo() {
return mService;
}
public void discoverServices() {
mNsdManager.discoverServices(
SERVICE_TYPE, NsdManager.PROTOCOL_DNS_SD, mDiscoveryListener);
}
}
XML
<Button
android:id="#+id/btn_discover_networks"
android:layout_width="match_parent"
android:layout_height="50dp"
android:onClick="onClickDiscover"
android:text="Discover Networks"/>

Why don't you make mNsdUtils to be a member field if it should be accessed from the outside of the function?
The root cause saying mNsdUtils is null from the MainActivity.onClickDiscover() implementation.
Implement in the method itself, as the context is different throwing a null pointer exception.
A small tip for you: read the stack trace and find your source code(for your case, MainActivity.java) to locate what was the first error from bottom to up.
Caused by: java.lang.NullPointerException: Attempt to invoke virtual method 'void com.example.android.implicitintents.Utils.NsdUtils.discoverServices()' on a null object reference
at com.example.android.implicitintents.MainActivity.onClickDiscoverAura(MainActivity.java:40)
at java.lang.reflect.Method.invoke(Native Method)
at android.support.v7.app.AppCompatViewInflater$DeclaredOnClickListener.onClick(AppCompatViewInflater.java:288)
at android.view.View.performClick(View.java:5637)
at android.view.View$PerformClick.run(View.java:22429)
at android.os.Handler.handleCallback(Handler.java:751)
at android.os.Handler.dispatchMessage(Handler.java:95)
at android.os.Looper.loop(Looper.java:154)
at android.app.ActivityThread.main(ActivityThread.java:6119)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:886)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:776)
This is the one you need.
at com.example.android.implicitintents.MainActivity.onClickDiscoverAura(MainActivity.java:40)

There is nothing wrong with onClick. Please read your following log :
Caused by: java.lang.NullPointerException: Attempt to invoke virtual method 'void com.example.android.implicitintents.Utils.NsdUtils.discoverServices()' on a null object reference
It means that inside onClick "mNsdUtils" is null. For more assistance please post your NsdUtils class.
Do the following and your app won't crash:
public void onClickDiscover(View view){
if(mNsdUtils != null) //add this line
mNsdUtils.discoverServices();
}

onClickListener is working just fine. You have to instantiate NSD object globally and then use it.

NullPointerException: Attempt to invoke virtual method ... on a null object reference [duplicate]

This question already has answers here:
Can not find a View with findViewById()
(4 answers)
Closed 6 years ago.
When I start my SettingsActivity, I get the following Error, but I don't know why, because I have done everything as always.
ERROR:
FATAL EXCEPTION: main Process: com.android.niklasvlach.vertretung, PID: 9175
java.lang.RuntimeException: Unable to start activity ComponentInfo{com.android.niklasvlach.vertretung/com.android.niklasvlach.vertretung.SettingsActivity}: java.lang.NullPointerException: Attempt to invoke virtual method 'void android.widget.Spinner.setOnItemSelectedListener(android.widget.AdapterView$OnItemSelectedListener)' on a null object reference at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2358) at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2420) at android.app.ActivityThread.access$900(ActivityThread.java:154) at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1321) at android.os.Handler.dispatchMessage(Handler.java:102) at android.os.Looper.loop(Looper.java:135) at android.app.ActivityThread.main(ActivityThread.java:5294) at java.lang.reflect.Method.invoke(Native Method) at java.lang.reflect.Method.invoke(Method.java:372) at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:904) at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:699) Caused by: java.lang.NullPointerException: Attempt to invoke virtual method 'void android.widget.Spinner.setOnItemSelectedListener(android.widget.AdapterView$OnItemSelectedListener)' on a null object reference at com.android.niklasvlach.vertretung.SettingsActivity.onCreate(SettingsActivity.java:28) at android.app.Activity.performCreate(Activity.java:5990) at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1106) at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2311) at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2420)  at android.app.ActivityThread.access$900(ActivityThread.java:154)  at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1321)  at android.os.Handler.dispatchMessage(Handler.java:102)  at android.os.Looper.loop(Looper.java:135)  at android.app.ActivityThread.main(ActivityThread.java:5294)  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:904)  at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:699) 
The Code:
public class SettingsActivity extends AppCompatActivity {
Spinner select;
EditText username;
EditText password;
#Override
protected void onCreate(Bundle savedInstanceState) {
select = (Spinner) findViewById(R.id.selectclass);
username = (EditText) findViewById(R.id.username_view);
password = (EditText) findViewById(R.id.password_view);
select.setOnItemSelectedListener(new AdapterView.OnItemSelectedListener() {
public void onItemSelected(AdapterView<?> arg0, View arg1, int pos, long text) {
Toast.makeText(SettingsActivity.this,"" + text,Toast.LENGTH_LONG).show();
}
public void onNothingSelected(AdapterView<?> arg0) {
}
});
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_settings);
}
}
If anything else is needed, I will post it!

You need to do your UI work after setting the layout of the Activity.
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_settings);
select = (Spinner) findViewById(R.id.selectclass);
username = (EditText) findViewById(R.id.username_view);
password = (EditText) findViewById(R.id.password_view);
select.setOnItemSelectedListener(new AdapterView.OnItemSelectedListener() {
public void onItemSelected(AdapterView<?> arg0, View arg1, int pos, long text) {
Toast.makeText(SettingsActivity.this,"" + text,Toast.LENGTH_LONG).show();
}
public void onNothingSelected(AdapterView<?> arg0) {
}
});
}

Error java.lang.NullPointerException: Attempt to invoke virtual method 'java.lang.Object android.content.Context.getSystemService

I'm creating a simple Android Class that update a variable with the most recent value readed from some specific sensors (Light, temp and more), which I access it(sensor value) by getData() method, but i'm getting an error. I hope u can help me!
Here is my generic sensor class.
MySensor
public class mySensor extends Service implements SensorEventListener {
private SensorManager mSensorManager =null;
private Sensor s=null;
float data = 0;
public void onCreate(){
super.onCreate();
mSensorManager= (SensorManager) getSystemService(Context.SENSOR_SERVICE);
}
public mySensor(int type){
//HERE I'M GETTING THE ERROR
s= mSensorManager.getDefaultSensor(type);
}
public String getData(){
return String.valueOf(data);
}
#Override
public IBinder onBind(Intent intent) {
return null;
}
#Override
public void onSensorChanged(SensorEvent event) {
if (event.sensor.getType() == Sensor.TYPE_LIGHT) {
data = event.values[0];
}
}
#Override
public void onAccuracyChanged(Sensor sensor, int i) {
}
protected void onResume() {
mSensorManager.registerListener((SensorEventListener) this, s, SensorManager.SENSOR_DELAY_NORMAL);
}
protected void onPause() {
// super.onPause();
mSensorManager.unregisterListener((SensorEventListener) this);
}
}
Here is the log
...
E/AndroidRuntime: FATAL EXCEPTION: main
Process: project.luke.com.sensorreader, PID: 25297
java.lang.RuntimeException: Unable to start activity ComponentInfo{project.luke.com.sensorreader/project.luke.com.sensorreader.MainActivity}: java.lang.NullPointerException: Attempt to invoke virtual method 'android.hardware.Sensor android.hardware.SensorManager.getDefaultSensor(int)' on a null object reference
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2460)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2522)
at android.app.ActivityThread.access$800(ActivityThread.java:169)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1421)
at android.os.Handler.dispatchMessage(Handler.java:111)
at android.os.Looper.loop(Looper.java:194)
at android.app.ActivityThread.main(ActivityThread.java:5546)
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:967)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:762)
Caused by: java.lang.NullPointerException: Attempt to invoke virtual method 'android.hardware.Sensor android.hardware.SensorManager.getDefaultSensor(int)' on a null object reference
at project.luke.com.sensorreader.mySensor.<init>(mySensor.java:39)
at project.luke.com.sensorreader.MainActivity.onCreate(MainActivity.java:32)
at android.app.Activity.performCreate(Activity.java:5975)
at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1111)
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2413)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2522) 
at android.app.ActivityThread.access$800(ActivityThread.java:169) 
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1421) 
at android.os.Handler.dispatchMessage(Handler.java:111) 
at android.os.Looper.loop(Looper.java:194) 
at android.app.ActivityThread.main(ActivityThread.java:5546) 
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:967) 
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:762) 
In my MainActivity class I simple call mLight=new mySensor(Sensor.TYPE_LIGHT); but this trigger the error, cause mSensorManager=null, always.

From your MainActivity:
Intent intent = new Intent(this, mySensor.class);
intent.putExtra("type", Sensor.TYPE_LIGHT);
and within your service:
#Override
public IBinder onBind(Intent intent) {
mSensorManager= (SensorManager) getSystemService(Context.SENSOR_SERVICE);
int type = intent.getExtras().get("type");
s= mSensorManager.getDefaultSensor(type);
return null;
}
then you can remove:
public mySensor(int type){
...
}
and eventually the code you wrote within the onCreate.

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.

java.lang.NullPointerException in Admob while showing Rewarded Video

In Android,When I tried to load the Ad in Admob and there is no internet connection the code reaches onRewardedVideoAdFailedToLoad() and after sometime say 30 sec the app force closes with the below mentioned error.
I hope this is not the null pointer exception that I can handle. It is happening in the SDK I guess. Please let me know how to resolve this.
Code
private void setRewardedVideo() {
rewardedVideoAd = MobileAds.getRewardedVideoAdInstance(this);
rewardedVideoAd.setUserId(REWARD);
AdRequest adRequest = new AdRequest.Builder().build();
rewardedVideoAd.loadAd(AD_UNIT_ID_REWARDED_VIDEO_AD, adRequest);
rewardedVideoAd.setRewardedVideoAdListener(new RewardedVideoAdListener() {
#Override
public void onRewardedVideoAdLoaded() {
System.out.println("onRewardedVideoAdLoaded()");
if (rewardedVideoAd.isLoaded()) {
rewardedVideoAd.show();
}
}
#Override
public void onRewardedVideoAdOpened() {
System.out.println("onRewardedVideoAdOpened()");
}
#Override
public void onRewardedVideoStarted() {
System.out.println("onRewardedVideoStarted()");
}
#Override
public void onRewardedVideoAdClosed() {
System.out.println("onRewardedVideoAdClosed()");
}
#Override
public void onRewarded(RewardItem rewardItem) {
System.out.println("onRewarded()");
}
#Override
public void onRewardedVideoAdLeftApplication() {
System.out.println("onRewardedVideoAdLeftApplication()");
}
#Override
public void onRewardedVideoAdFailedToLoad(int i) {
System.out.println("onRewardedVideoAdFailedToLoad()");
}
});
}
Logcat
java.lang.NullPointerException: Attempt to invoke virtual method 'android.view.ViewParent com.google.android.gms.ads.internal.au.getParent()' on a null object reference
at com.google.android.gms.ads.internal.a.b(SourceFile:513)
at com.google.android.gms.ads.internal.b.b(SourceFile:318)
at com.google.android.gms.ads.internal.a.c(SourceFile:520)
at com.google.android.gms.ads.internal.aq.run(SourceFile:64)
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:5296)
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:899)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:694)

Ensure the user has connectivity before even trying to load the ads, there may be some deeper issue with AdMob that forces this NPE despite no internet.
private void setRewardedVideo() {
if (!isNetworkAvailable()) {
// Log no internet
return;
}
rewardedVideoAd = MobileAds.getRewardedVideoAdInstance(this);
rewardedVideoAd.setUserId(REWARD);
....
}
It may even make sense to ensure user has internet before trying to use adMob incase it is something with their library that is causing the issue. See this answer for that.