Android：在添加子項後重繪GridView

Question

我正在嘗試創建一個GridView，它可以讓用戶創建一個點擊GridView上最後一項的新子項。我有一個重繪視圖的問題。事實上，在用戶通過alertdialog創建一個新的孩子後，我需要刷新gridview才能看到這個孩子。我一直在尋找了一段時間，一切的解決方案，我發現是：

adapter.notifyDataSetChanged(); 
gridView.invalidateViews(); 
gridView.setAdapter(adapter); 

這是我的代碼的一部分，但不會，至少表面上，做任何事情。下面的代碼只是android模板中的PlaceholderFragment類的onCreateView（）方法，用於通過滑動選項卡進行活動。這裏的應用程序開發仍然是開始，但我已經堅持這個問題..

public View onCreateView(LayoutInflater inflater, ViewGroup container, 
      Bundle savedInstanceState) { 
     final View rootView = inflater.inflate(R.layout.fragment_one, container, false); 
     final GridView gridView = (GridView) rootView.findViewById(R.id.gridview); 
     final GridAdapter adapter =new GridAdapter(getActivity()); 
     gridView.setAdapter(adapter); 
     gridView.setOnItemClickListener(new AdapterView.OnItemClickListener() { 
      public void onItemClick(AdapterView<?> parent, View v, 
            int position, long id) { 
       if(position==0){ 
        LayoutInflater inflater = getActivity().getLayoutInflater(); 
        View newidea= inflater.inflate(R.layout.newidea, null); 
        final TextView txtname = ((TextView) newidea.findViewById(R.id.name)); 
        final TextView txtdesc = ((TextView) newidea.findViewById(R.id.desc)); 
        final Spinner spinner=((Spinner)newidea.findViewById(R.id.spinner)); 
        AlertDialog.Builder builder = new AlertDialog.Builder(getActivity()); 
        builder.setIcon(R.drawable.type_add) 
          .setPositiveButton("Create", new DialogInterface.OnClickListener() { 
           public void onClick(DialogInterface dialog, int id) { 
            String name = txtname.getText().toString(); 
            String desc = txtdesc.getText().toString(); 
            DataReceiver dr = new DataReceiver(getActivity().getBaseContext(), name, desc,Integer.toString(spinner.getSelectedItemPosition())); 
            dr.writeFile(); 
            dialog.dismiss(); 
            adapter.notifyDataSetChanged(); 
            gridView.invalidateViews(); 
            gridView.setAdapter(adapter); 
           } 
          }).setNegativeButton("Forgot the idea?", new DialogInterface.OnClickListener() { 
         public void onClick(DialogInterface dialog, int id) { 
          dialog.dismiss(); 
         } 
        }).setView(newidea) 
          .setTitle("New Idea"); 
        AlertDialog dialog = builder.create(); 
        dialog.show(); 
       } else { 
        Toast.makeText(
          getActivity(), 
          ((TextView) v.findViewById(R.id.grid_item_label)) 
            .getText(), Toast.LENGTH_SHORT).show(); 
       } 

      } 
     }); 

     return rootView; 
    } 

} 

代碼發佈請求後更新。

這是GridAdapter。一切工作正常，唯一的是，我仍然必須關閉並重新打開應用程序，以查看gridview重繪和更新。

public class GridAdapter extends BaseAdapter { 
private Context context; 
boolean filesyet; 
File f[]; 
public GridAdapter(Context context) { 
    this.context = context; 
    filesyet=filesYet(); 
} 

@Override 
public Object getItem(int i) { 
    return null; 
} 

@Override 
public long getItemId(int i) { 
    return 0; 
} 

public View getView(int position, View convertView, ViewGroup parent) { 

    LayoutInflater inflater = (LayoutInflater) context 
      .getSystemService(Context.LAYOUT_INFLATER_SERVICE); 
    View gridView; 
    if (convertView == null) { 
     gridView = inflater.inflate(R.layout.griditem, null); 
     TextView title = (TextView) gridView 
       .findViewById(R.id.grid_item_label); 
     LinearLayout background = (LinearLayout) gridView 
       .findViewById(R.id.grid_item); 

     if(position==0){ 
      title.setText(""); 
      Drawable d= context.getResources().getDrawable(R.drawable.type_add); 
      background.setBackground(d); 
     }else { 
      title.setText(f[position].getName()); 
      Drawable d; 
      int selected=0; 
      try { 
       byte[] buffer = new byte[1]; 
       new FileInputStream(f[position]).read(buffer,0,buffer.length); 
       selected=Integer.valueOf(new String(buffer)); 
      } catch (FileNotFoundException e){ 
       e.printStackTrace(); 
      } catch (IOException e){ 
       e.printStackTrace(); 
      } 
      switch(selected){ 
       case 1: 
        d=context.getResources().getDrawable(R.drawable.type_app); 
        break; 
       case 2: 
        d=context.getResources().getDrawable(R.drawable.type_engi); 
        break; 
       case 3: 
        d=context.getResources().getDrawable(R.drawable.type_event); 
        break; 
       default: 
        d=context.getResources().getDrawable(R.drawable.eureka); 
        break; 
      } 
      background.setBackground(d); 
     } 

    } else { 
     gridView = (View) convertView; 
    } 

    return gridView; 
} 

@Override 
public int getCount() { 
    if (filesyet) { 
     return f.length; 
    } else { 
     return 1; 
    } 
} 

Boolean filesYet(){ 
    try { 
     String path = context.getFilesDir().toString(); 
     this.f = new File(path).listFiles(); 
     System.out.println(f.toString()); 
     return true; 
    } catch (NullPointerException e){ 
     System.out.println("NULL"); 
     return false; 
    } 
} 

感謝您的幫助

Answer 1

在構造函數中創建的適配器時，您只能加載文件的列表。由於您沒有創建新的構造函數，因此不會再調用filesYet（）方法，並且文件列表不會更新。

爲了使這個更新你可以覆蓋notifydatasetchanged功能在適配器

@Override 
public void notifyDataSetChanged(){ 
    filesyet = filesYet(); 
    super.notifyDataSetChanged(); 
}