My build completed successfully but the app crashed. Would someone write a tutorial on how to link Firebase Auth with Facebook Login in Android Studio using Viewpager and Fragments as in my code? I need a slider in my app.
private SectionsPagerAdapter mSectionsPagerAdapter;
private ViewPager mViewPager;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activitenter code herey_main);
mSectionsPagerAdapter = new SectionsPagerAdapter(getSupportFragmentManager());
// Set up the ViewPager with the sections adapter.
mViewPager = (ViewPager) findViewById(R.id.container);
enter code here
mViewPager.setAdapter(mSectionsPagerAdapter);
mAuth = FirebaseAuth.getInstance();
// Initialize Facebook Login button
mCallbackManager = CallbackManager.Factory.create();
LoginButton loginButton = findViewById(R.id.login_button);
//Here problem start
loginButton.setReadPermissions("email", "public_profile");
loginButton.registerCallback(mCallbackManager, new
FacebookCallback() {
@Override
enter code here
public void onSuccess(LoginResult loginResult) {
Log.d(TAG, "facebook:onSuccess:" + loginResult);
handleFacebookAccessToken(loginResult.getAccessToken());
}
@Override
public void onCancel() {
Log.d(TAG, "facebook:onCancel");
// ...
}
@Override
public void onError(FacebookException error) {
Log.d(TAG, "facebook:onError", error);
// ...
}
});
// ...
}
@Override
public void onStart() {
super.onStart();
// Check if user is signed in (non-null) and update UI accordingly.
FirebaseUser currentUser = mAuth.getCurrentUser();
if(currentUser != null){
updateUI();
}
}
private void updateUI() {
Toast.makeText(MainActivity.this, "You are logged in!" ,
Toast.LENGTH_LONG).show();
}
@Override
protected void onActivityResult(int requestCode, int resultCode, Intent data) {
super.onActivityResult(requestCode, resultCode, data);
// Pass the activity result back to the Facebook SDK
mCallbackManager.onActivityResult(requestCode, resultCode, data);
}
private void handleFacebookAccessToken(AccessToken token) {
Log.d(TAG, "handleFacebookAccessToken:" + token);
AuthCredential credential = FacebookAuthProvider.getCredential(token.getToken());
mAuth.signInWithCredential(credential)
.addOnCompleteListener(this, new OnCompleteListener() {
@Override
public void onComplete(@NonNull Task task) {
if (task.isSuccessful()) {
// Sign in success, update UI with the signed-in user's information
Log.d(TAG, "signInWithCredential:success");
FirebaseUser user = mAuth.getCurrentUser();
updateUI();
} else {
// If sign in fails, display a message to the user.
Log.w(TAG, "signInWithCredential:failure", task.getException());
Toast.makeText(MainActivity.this, "Authentication failed."[enter image description here][1],
Toast.LENGTH_SHORT).show();
}
// ...
}
});
}
/**
* A placeholder fragment containing a simple view.
*/
public static class PlaceholderFragment extends Fragment {
/**
* The fragment argument representing the section number for this
* fragment.
*/
private static final String ARG_SECTION_NUMBER = "section_number";
public PlaceholderFragment() {
}
/**
* Returns a new instance of this fragment for the given section
* number.
*/
public static PlaceholderFragment newInstance(int sectionNumber) {
PlaceholderFragment fragment = new PlaceholderFragment();
Bundle args = new Bundle();
args.putInt(ARG_SECTION_NUMBER, sectionNumber);
fragment.setArguments(args);
return fragment;
}
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
View rootView = null;
switch (getArguments().getInt(ARG_SECTION_NUMBER)) {
case 1:
rootView = inflater.inflate(R.layout.fragment_main, container, false);
break;
case 2:
rootView = inflater.inflate(R.layout.fragment_second, container, false);
break;
}
return rootView;
}
}
/**
* A {@link FragmentPagerAdapter} that returns a fragment corresponding to
* one of the sections/tabs/pages.
*/
public class SectionsPagerAdapter extends FragmentPagerAdapter {
public SectionsPagerAdapter(FragmentManager fm) {
super(fm);
}
@Override
public Fragment getItem(int position) {
// getItem is called to instantiate the fragment for the given page.
// Return a PlaceholderFragment (defined as a static inner class below).
return PlaceholderFragment.newInstance(position + 1);
}
@Override
public int getCount() {
// Show 2 total pages.
return 2;`enter code here`
}
}
The app without fragments works perfectly. Does anybody have any idea why?
This is exception:
2019-01-19 11:13:05.129 8439-8439/jimmy.jimmyfindgymbuddyptl.com.myapplication E/AndroidRuntime: FATAL EXCEPTION: main
Process: jimmy.jimmyfindgymbuddyptl.com.myapplication, PID: 8439
java.lang.RuntimeException: Unable to start activity ComponentInfo{jimmy.jimmyfindgymbuddyptl.com.myapplication/jimmy.jimmyfindgymbuddyptl.com.myapplication.MainActivity}: java.lang.NullPointerException: Attempt to invoke virtual method 'void com.facebook.login.widget.LoginButton.setReadPermissions(java.lang.String[])' on a null object reference
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2646)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2707)
at android.app.ActivityThread.-wrap12(ActivityThread.java)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1460)
at android.os.Handler.dispatchMessage(Handler.java:102)
at android.os.Looper.loop(Looper.java:154)
at android.app.ActivityThread.main(ActivityThread.java:6077)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:866)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:756)
Caused by: java.lang.NullPointerException: Attempt to invoke virtual method 'void com.facebook.login.widget.LoginButton.setReadPermissions(java.lang.String[])' on a null object reference
at jimmy.jimmyfindgymbuddyptl.com.myapplication.MainActivity.onCreate(MainActivity.java:92)
at android.app.Activity.performCreate(Activity.java:6662)
at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1118)
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2599)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2707)
at android.app.ActivityThread.-wrap12(ActivityThread.java)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1460)
at android.os.Handler.dispatchMessage(Handler.java:102)
at android.os.Looper.loop(Looper.java:154)
at android.app.ActivityThread.main(ActivityThread.java:6077)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:866)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:756)
this button was in xml:
android:layout_above="@+id/textView7" android:layout_alignParentStart="true"
android:layout_marginStart="95dp" android:layout_marginBottom="6dp" />
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