來自FragmentActivity的Fragment中的Grid.Invalidate

我是Android的nuebie。我想我是嘗試從非UI線程運行代碼。我如何在片段中更新我的網格。我有活動SimpleImageActivity。在這個活動中，我正在等待返回鍵，我試圖在GridView中更新我的數據。方法invalidate() postInvalidate()沒事幹。來自FragmentActivity的Fragment中的Grid.Invalidate

private Handler handler; 
protected OnBackPressedListener onBackPressedListener; 

public void setOnBackPressedListener(OnBackPressedListener onBackPressedListener) { 
    this.onBackPressedListener = onBackPressedListener; 
} 

@Override 
public void onCreate(Bundle savedInstanceState) { 
    super.onCreate(savedInstanceState); 

    Fragment fr; 
    String tag= GridViewFragment.class.getSimpleName(); 
    fr = getSupportFragmentManager().findFragmentByTag(tag); 
    if (fr == null) { 
     fr = new GridViewFragment(); 
     } 
    getSupportFragmentManager().beginTransaction().replace(android.R.id.content, fr, tag).commit(); 
} 

@Override 
public void onBackPressed() { 
    if (onBackPressedListener != null){ 
     // ...some code... 
     handler = new Handler(); 
     handler.postDelayed(new Runnable() { 
      public void run() { 
       System.out.println("[VAN] I am in Runnable"); 
       GridView gV = (GridView)findViewById(R.id.grid); // gV - links to my GridView and not null here 
       gV.invalidate(); //this code nothing doing 
       gV.postInvalidate(); //this code nothing doing too 

      } 
     }, 0); 
     onBackPressedListener.onBackPres(); // event Back key for fragment 
}

在我GridViewFragment我想執行gridView.invalidate過，但在下面的GridView = NULL

public class GridViewFragment extends AbsListViewBaseFragment implements OnBackPressedListener { 

public GridView gridView; 
private FragmentActivity activity; 
View rootView; 

public GridViewFragment() { 
    this.activity = getActivity(); 
} 

@Override 
public void onBackPres() { 
    new Thread(new Runnable() { 
     public void run() { 
      updateScreen(); 
      // I am try this 
      // gridView.invalidate() there not working, because gridView=null 
      // 
      System.out.println("[VAN] updateScreen"); 
     } 
    }).start(); 
} 

@Override 
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) { 
    activity = getActivity(); 
    ((SimpleImageActivity)activity).setOnBackPressedListener(new GridViewFragment()); 

    rootView = inflater.inflate(R.layout.fragment_image_grid, container, false); 
    gridView = (GridView) rootView.findViewById(R.id.grid); 
    // ... some code ... 
} 

private void updateScreen(){ 
    gridView.postInvalidate(); // error because there gridView=null 
}

如何更新我的GridView的片段？當在片段gridView.invalidate中觸發方法public void onBackPres() { - 由於gridView = null而不工作。當在活動中使用handler.postDelayed(new Runnable() { gv返回我的GridView，但是 gV.invalidate(); gV.postInvalidate(); 沒有做任何事情並且沒有任何錯誤地執行。

來源

2016-04-26 van4ik

儘量按照這個http://stackoverflow.com/questions/11123621/running-code-in-main-線程從另一個線程 – Amit

謝謝，在你的建議後，我試着將''gV.invalidate（）;'替換爲'gV.invalidateViews（）;'它可以工作 – van4ik

一個找到了答案我自己的問題

handler = new Handler(); 
    handler.post(new Runnable() { 
     public void run() { 
      GridView gV = (GridView)findViewById(R.id.grid); 
      gV.invalidateViews(); //this works fine 
     } 
    });

使用invalidateViews()代替invalidate()

來源

2016-04-26 17:40:50 van4ik

來自FragmentActivity的Fragment中的Grid.Invalidate

回答

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