Bewegen von Fragment zu Aktivität, die erweitert FragmentOctivity

Question

Ich habe mich einloggen Fragment, nach erfolgreicher Authentifizierung ich navigiere zu einer Aktivität "AfterLogin", die page viewPager enthält. folgenden Code Durch die Verwendung von:

Toast.makeText(getActivity(), "Login Successfull", Toast.LENGTH_LONG).show(); 
       progressDialog.dismiss(); 
       Intent intent = new Intent(getActivity(),AfterLogin.class); 
       startActivity(intent); 
      } 
     }); 

i Code unten in AfterLogin.java hat, das ist meine zweite Aktivitäts- von Fragmente zu navigieren.

public class AfterLogin extends FragmentActivity { 
    ViewPager viewPager=null; 

    @Override 
    protected void onCreate(Bundle savedInstanceState) { 
     super.onCreate(savedInstanceState); 
     setContentView(R.layout.activity_main); 

     viewPager = (ViewPager) findViewById(R.id.pager); 

     FragmentManager fragmentManager = getSupportFragmentManager(); 

     viewPager.setAdapter(new MyAdapter(fragmentManager)); 

     ActionBar actionBar = getActionBar(); 
     actionBar.setDisplayHomeAsUpEnabled(true); 
    } 


} 

class MyAdapter extends FragmentStatePagerAdapter { 
    public MyAdapter(FragmentManager fm) { 
     super(fm); 
    } 

    @Override 
    public Fragment getItem(int position) { 

     Fragment fragment = null; 
     //Log.d("info", "get item called" +position); 
     if(position == 0){ 

      fragment = new AttendanceResultFeed(); 
     } 

     if(position == 1){ 

      fragment = new CollegeFeedFrag(); 
     } 

     if(position == 2){ 

      fragment = new BranchFeedFrag(); 
     } 
     return fragment; 
    } 

    @Override 
    public int getCount() { 
     // Log.d("info", "get count called"); 
     return 3; 
    } 

    @Override 
    public CharSequence getPageTitle(int position) { 

     if (position == 0){ 

      return "Attendance and Result"; 
     } 

     if (position == 1){ 

      return "College Feeds"; 
     } 

     if (position == 2){ 

      return "Branch Feeds"; 
     } 
     return super.getPageTitle(position); 
    } 

Während dieser i Prozess i Störung erhalten:

AfterLogin}:

java.lang.NullPointerException: Attempt to invoke virtual method 'void android.support.v4.view.ViewPager.setAdapter(android.support.v4.view.PagerAdapter)' on a null object reference 
                       at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2298) 
                       at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2360) 
                       at android.app.ActivityThread.access$800(ActivityThread.java:144) 
                       at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1278) 
                       at android.os.Handler.dispatchMessage(Handler.java:102) 
                       at android.os.Looper.loop(Looper.java:135) 
                       at android.app.ActivityThread.main(ActivityThread.java:5221) 
                       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) 
                      Caused by: java.lang.NullPointerException: Attempt to invoke virtual method 'void android.support.v4.view.ViewPager.setAdapter(android.support.v4.view.PagerAdapter)' on a null object reference 
                       at com.rakesh_kr.master_piece.AfterLogin.onCreate(AfterLogin.java:26) 
                       at android.app.Activity.performCreate(Activity.java:5937) 
                       at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1105) 
                       at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2251) 
                       at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2360)  
                       at android.app.ActivityThread.access$800(ActivityThread.java:144)  
                       at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1278)  
                       at android.os.Handler.dispatchMessage(Handler.java:102)  
                       at android.os.Looper.loop(Looper.java:135)  
                       at android.app.ActivityThread.main(ActivityThread.java:5221)  
                       at java.lang.reflect.Method.invoke(Native Method)  

kann mir helfen, dies zu slove.

Wenn ich AfterLogin von einem separaten Projekt ausführen, funktioniert es gut.

Answer 1

Ich habe die Lösung für dieses Problem gefunden. Es wurde unter Beitrag erwähnt in

https://stackoverflow.com/questions/31822215/attempt-to-invoke-virtual-method-void-android-support-v4-view-viewpager-setadap]

Answer 2

try this:

startActivity(new Intent(getApplicationContext(), XXXX.class)); 

mir sagen, wie es geht