Исключение Null pointer при передаче значений из Activity в Fragment

Question

Это мой класс MainActivity. Из этого класса я пытаюсь отправить данные в свой фрагмент «HomeFragment», а затем запустить второе действие «SwipeMainActivity».

Это какая-то часть кодирования:

@Override 
     public void onItemClick(AdapterView<?> parent, View view, int position, long id) { 
      Title clickedTitle = mAdapter.getItem(position); 
      Log.d(TAG, "clickedItem : " + clickedTitle.getTitleName()); 
      Intent intent = new Intent(this, SwipeMainActivity.class); 
      HomeFragment fragobj=new HomeFragment(); 
      Bundle bundle = new Bundle(); 
      bundle.putLong(HomeFragment.EXTRA_SELECTED_TITLE_ID, clickedTitle.getId()); 
      fragobj.setArguments(bundle); 
    //  intent.putExtra(SwipeMainActivity.EXTRA_SELECTED_TITLE_ID, clickedTitle.getId()); 
      startActivity(intent); 

Это мой SwipeMainActivity Класс

public class SwipeMainActivity extends AppCompatActivity { 
     Toolbar toolbar; 
     TabLayout tabLayout; 
     ViewPager viewPager; 
     ViewPagerAdapter viewPagerAdapter; 
     private String mTitleId; 
     public static final String EXTRA_SELECTED_TITLE_ID = "extra_key_selected_title_id"; 

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

      toolbar = (Toolbar) findViewById(R.id.toolBar); 
      setSupportActionBar(toolbar); 


      tabLayout=(TabLayout) findViewById(R.id.tabLayout); 
      viewPager= (ViewPager) findViewById(R.id.viewPager); 
      viewPagerAdapter=new ViewPagerAdapter(getSupportFragmentManager()); 
      viewPagerAdapter.addFragment(new HomeFragment(),"HOME"); 
      viewPagerAdapter.addFragment(new TopFreeFragment(),"Free"); 
      viewPagerAdapter.addFragment(new TopPaidFragment(),"Paid"); 
      viewPager.setAdapter(viewPagerAdapter); 
      tabLayout.setupWithViewPager(viewPager); 

     } 
    } 

А потом, мой HomeFragment:

public class HomeFragment extends ListFragment implements AdapterView.OnItemLongClickListener, AdapterView.OnItemClickListener,View.OnClickListener{ 

    public static final String EXTRA_SELECTED_TITLE_ID = "extra_key_selected_title_id"; 
    Long i; 

    public HomeFragment() { 
     // Required empty public constructor 
    } 


    @Override 
    public View onCreateView(LayoutInflater inflater, ViewGroup container, 
          Bundle savedInstanceState) { 
     Bundle bundle = getArguments(); 
//  if (bundle != null) { 

      i = bundle.getLong(this.EXTRA_SELECTED_TITLE_ID, -1); 
//  } 
     return inflater.inflate(R.layout.fragment_home, container, false); 
    } 

Я получил эту ошибку:

02-24 00:34:02.266 15575-15575/com.kawlni.silence.bekang W/dalvikvm: threadid=1: thread exiting with uncaught exception (group=0x40015560) 
02-24 00:34:02.276 15575-15575/com.kawlni.silence.bekang E/AndroidRuntime: FATAL EXCEPTION: main 
    java.lang.NullPointerException 
     at com.kawlni.silence.bekang.Swipe.HomeFragment.onCreateView(HomeFragment.java:58) 
     at android.support.v4.app.Fragment.performCreateView(Fragment.java:1962) 
     at android.support.v4.app.FragmentManagerImpl.moveToState(FragmentManager.java:1067) 
     at android.support.v4.app.FragmentManagerImpl.moveToState(FragmentManager.java:1248) 
     at android.support.v4.app.BackStackRecord.run(BackStackRecord.java:738) 
     at android.support.v4.app.FragmentManagerImpl.execPendingActions(FragmentManager.java:1613) 
     at android.support.v4.app.FragmentManagerImpl.executePendingTransactions(FragmentManager.java:570) 
     at android.support.v4.app.FragmentPagerAdapter.finishUpdate(FragmentPagerAdapter.java:141) 
     at android.support.v4.view.ViewPager.populate(ViewPager.java:1106) 
     at android.support.v4.view.ViewPager.populate(ViewPager.java:952) 
     at android.support.v4.view.ViewPager.onMeasure(ViewPager.java:1474) 
     at android.view.View.measure(View.java:8313) 
     at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:3138) 
     at android.widget.LinearLayout.measureChildBeforeLayout(LinearLayout.java:1017) 
     at android.widget.LinearLayout.measureVertical(LinearLayout.java:386) 
     at android.widget.LinearLayout.onMeasure(LinearLayout.java:309) 
     at android.view.View.measure(View.java:8313) 
     at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:3138) 
     at android.widget.FrameLayout.onMeasure(FrameLayout.java:250) 
     at android.support.v7.widget.ContentFrameLayout.onMeasure(ContentFrameLayout.java:135) 
     at android.view.View.measure(View.java:8313) 
     at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:3138) 
     at android.widget.LinearLayout.measureChildBeforeLayout(LinearLayout.java:1017) 
     at android.widget.LinearLayout.measureVertical(LinearLayout.java:386) 
     at android.widget.LinearLayout.onMeasure(LinearLayout.java:309) 
     at android.view.View.measure(View.java:8313) 
     at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:3138) 
     at android.widget.FrameLayout.onMeasure(FrameLayout.java:250) 
     at android.view.View.measure(View.java:8313) 
     at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:3138) 
     at android.widget.FrameLayout.onMeasure(FrameLayout.java:250) 
     at android.view.View.measure(View.java:8313) 
     at android.view.ViewRoot.performTraversals(ViewRoot.java:839) 
     at android.view.ViewRoot.handleMessage(ViewRoot.java:1859) 
     at android.os.Handler.dispatchMessage(Handler.java:99) 
     at android.os.Looper.loop(Looper.java:123) 
     at android.app.ActivityThread.main(ActivityThread.java:3683) 
     at java.lang.reflect.Method.invokeNative(Native Method) 
     at java.lang.reflect.Method.invoke(Method.java:507) 
     at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:839) 
     at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:597) 
     at dalvik.system.NativeStart.main(Native Method) 

Answer 1

Вы можете использовать этот метод фабричный подход, чтобы создать новый экземпляр вашего фрагмента, используя предоставленные параметры.

public static final String EXTRA_SELECTED_TITLE_ID = "extra_key_selected_title_id"; 

private Long mTitleId; 


public static HomeFragment newInstance(Long titleId) { 
    HomeFragment fragment = new HomeFragment(); 
    Bundle args = new Bundle(); 
    args.putString(EXTRA_SELECTED_TITLE_ID, titleId); 
    fragment.setArguments(args); 
    return fragment; 
} 

public HomeFragment() { 
    // Required empty public constructor 
} 

@Override 
public void onCreate(Bundle savedInstanceState) { 
    super.onCreate(savedInstanceState); 
    if (getArguments() != null) { 
     mTitleId = getArguments().getString(EXTRA_SELECTED_TITLE_ID); 
    } 
} 

@Override 
public View onCreateView(LayoutInflater inflater, ViewGroup container, 
         Bundle savedInstanceState) {  
    Log.d(LOG_TAG , "EXTRA_SELECTED_TITLE_ID = " + mTitleId); 
    return inflater.inflate(R.layout.fragment_home, container, false); 
} 

используется метод так:

HomeFragment fragobj = HomeFragment.newInstance(clickedTitle.getId());