Exapandable listview不工作在android中的片段活動

我在片段中使用可展開的listview。但它不工作獲取LayoutInflater的空指針異常。Exapandable listview不工作在android中的片段活動

public class DemoActivity extends Fragment{ 
public static final String ARG_SECTION_NUMBER = "section_number"; 
ExpandableListAdapter listAdapter; 
ExpandableListView expListView; 
List<String> listDataHeader; 
HashMap<String, List<String>> listDataChild; 
Context mContext; 

public DemoActivity(Context context) { 
    this.mContext=DemoActivity.this.getActivity();; 
} 

@Override 
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) { 
    View rootView = inflater.inflate(R.layout.demo, container, false); 
    TextView dummyTextView = (TextView) rootView.findViewById(R.id.section_label_demo); 
    dummyTextView.setText(Integer.toString(getArguments().getInt(ARG_SECTION_NUMBER))); 
    // get the listview 
    expListView = (ExpandableListView) rootView.findViewById(R.id.lvExp); 

    // preparing list data 
    prepareListData(); 

    listAdapter = new ExpandableListAdapter(mContext, listDataHeader, listDataChild); 

    // setting list adapter 
    expListView.setAdapter(listAdapter); 

    // Listview Group click listener 
    expListView.setOnGroupClickListener(new OnGroupClickListener() { 

     @Override 
     public boolean onGroupClick(ExpandableListView parent, View v, 
       int groupPosition, long id) { 

      return false; 
     } 
    }); 

    // Listview Group expanded listener 
    expListView.setOnGroupExpandListener(new OnGroupExpandListener() { 

     @Override 
     public void onGroupExpand(int groupPosition) { 
      Toast.makeText(mContext, 
        listDataHeader.get(groupPosition) + " Expanded", 
        Toast.LENGTH_SHORT).show(); 
     } 
    }); 

    // Listview Group collasped listener 
    expListView.setOnGroupCollapseListener(new OnGroupCollapseListener() { 

     @Override 
     public void onGroupCollapse(int groupPosition) { 
      Toast.makeText(mContext,listDataHeader.get(groupPosition) + " Collapsed", 
        Toast.LENGTH_SHORT).show(); 

     } 
    }); 

    // Listview on child click listener 
    expListView.setOnChildClickListener(new OnChildClickListener() { 

     @Override 
     public boolean onChildClick(ExpandableListView parent, View v, 
       int groupPosition, int childPosition, long id) { 
      // TODO Auto-generated method stub 
      Toast.makeText(mContext,listDataHeader.get(groupPosition)+ " : "+ listDataChild.get(
          listDataHeader.get(groupPosition)).get(childPosition), Toast.LENGTH_SHORT).show(); 
      return false; 
     } 
    }); 
    return rootView; 
} 

private void prepareListData() { 
    listDataHeader = new ArrayList<String>(); 
    listDataChild = new HashMap<String, List<String>>(); 


    // Adding child data 
    List<String> list1 = new ArrayList<String>(); 
    list1.add("The Shawshank Redemption"); 

    List<String> nowShowing = new ArrayList<String>(); 

    nowShowing.add("Despicable Me 2"); 


    List<String> comingSoon = new ArrayList<String>(); 
    comingSoon.add("2 Guns"); 

    String[] data=search(); 
    // Adding child data 
    for(int i=0;i<search().length;i++) 
    { 
     listDataHeader.add(""+data[i]); 
     //Toast.makeText(mContext,data[i], Toast.LENGTH_SHORT).show(); 


     listDataChild.put(listDataHeader.get(i), list1); 

    } 
} 

public String[] search() 
{ 
    String[] filenames; 
    File file = new File(Environment.getExternalStorageDirectory(), "/Recording"); 
    if(!file.exists()){ 
     file.mkdirs(); 
    } 

    //filenames = new String[30]; 
    if(!file.list().equals("")) 
    { 
     filenames = file.list(); 
     int total = 0; 

     for (int i = 0; i< filenames.length; i++) 
     { 
      if (filenames[i].contains(".3gp")) 
      { 
       total++; 
      } 
     } 
    } 
    else 
    { 
     String[] filearray=new String[]{""}; 
     filenames=filearray; 
    } 
    return filenames; 
} 

    }

適配器講座

public class ExpandableListAdapter extends BaseExpandableListAdapter { 

private Context _context; 
private List<String> _listDataHeader; 
private HashMap<String, List<String>> _listDataChild; 
private EditText editTask; 
private CheckBox mCB; 
private ImageView mImageView; 


public ExpandableListAdapter(Context context, List<String> listDataHeader, 
     HashMap<String, List<String>> listChildData) { 
    this._context = context; 
    this._listDataHeader = listDataHeader; 
    this._listDataChild = listChildData; 

} 

@Override 
public Object getChild(int groupPosition, int childPosititon) { 
    return this._listDataChild.get(_listDataHeader.get(groupPosition)) 
      .get(childPosititon); 
} 

@Override 
public long getChildId(int groupPosition, int childPosition) { 
    return childPosition; 
} 

@Override 
public View getChildView(final int groupPosition, final int childPosition, 
     boolean isLastChild, View convertView, final ViewGroup parent) { 
    if (convertView == null) { 
     LayoutInflater infalInflater = (LayoutInflater) _context.getSystemService(Context.LAYOUT_INFLATER_SERVICE); 
     convertView = infalInflater.inflate(R.layout.list_item, null); 
    } 

    ImageView txtListChild = (ImageView) convertView.findViewById(R.id.lblListItem); 
    txtListChild.setOnClickListener(new OnClickListener() { 

     @Override 
     public void onClick(View v) { 
      // TODO Auto-generated method stub 

      String data[]=search(); 
      Intent i=new Intent(_context,DBRoulette.class); 
      i.putExtra("file_name", data[groupPosition]); 
      _context.startActivity(i); 

     } 
    }); 

    ImageView send = (ImageView) convertView.findViewById(R.id.send); 
    send.setOnClickListener(new OnClickListener() { 

     @Override 
     public void onClick(View v) { 
      // TODO Auto-generated method stub 
      String data[]=search(); 
      Intent i=new Intent(_context,XPlayer.class); 
      i.putExtra("file_name", data[groupPosition]); 
      _context.startActivity(i); 
     } 
    }); 


    mImageView=(ImageView) convertView.findViewById(R.id.editImage); 
    mImageView.setOnClickListener(new OnClickListener() { 

     @Override 
     public void onClick(View v) { 

      String data[]=search(); 
      Intent i=new Intent(_context,GoogleDrive.class); 
      i.putExtra("file_name", data[groupPosition]); 
      _context.startActivity(i); 

     } 
    }); 


    return convertView; 
} 

@Override 
public int getChildrenCount(int groupPosition) { 
    return _listDataChild.get(_listDataHeader.get(groupPosition)).size(); 
} 

@Override 
public Object getGroup(int groupPosition) { 
    return _listDataHeader.get(groupPosition); 
} 

@Override 
public int getGroupCount() { 
    return _listDataHeader.size(); 
} 

@Override 
public long getGroupId(int groupPosition) { 
    return groupPosition; 
} 

@Override 
public View getGroupView(int groupPosition, boolean isExpanded, 
     View convertView, ViewGroup parent) { 
    String headerTitle = (String) getGroup(groupPosition); 
    if (convertView == null) { 
     LayoutInflater infalInflater = (LayoutInflater)_context.getSystemService(Context.LAYOUT_INFLATER_SERVICE); 
      /***HERE I'M GETTING NULL POINTER EXCEPTION***/ 

     convertView = infalInflater.inflate(R.layout.list_group, null); 
    } 
    TextView lblListHeader = (TextView) convertView.findViewById(R.id.lblListHeader); 
    lblListHeader.setText(headerTitle); 
    return convertView; 
} 

@Override 
public boolean hasStableIds() { 
    return false; 
} 

@Override 
public boolean isChildSelectable(int groupPosition, int childPosition) { 
    return true; 
} 

public String[] search() 
    { 
    String[] filenames; 
     File file = new File(Environment.getExternalStorageDirectory(), "/Recording"); 
      if(!file.exists()){ 
       file.mkdirs(); 
      } 

     //filenames = new String[30]; 
     if(!file.list().equals(null)) 
     { 
     filenames = file.list(); 
     int total = 0; 

     for (int i = 0; i< filenames.length; i++) 
     { 
      if (filenames[i].contains(".3gp")) 
      { 
       total++; 
      } 
      } 
     } 
     else 
     { 
      String[] filearray=new String[]{""}; 
      filenames=filearray; 
     } 
     return filenames; 
    } 
    }

更新logcat的 -

10-16 15:15:44.011: E/AndroidRuntime(731): FATAL EXCEPTION: main 
10-16 15:15:44.011: E/AndroidRuntime(731): java.lang.NullPointerException 
10-16 15:15:44.011: E/AndroidRuntime(731):  at com.example.android.recorder.ExpandableListAdapter.getGroupView(ExpandableListAdapter.java:127) 
10-16 15:15:44.011: E/AndroidRuntime(731):  at android.widget.ExpandableListConnector.getView(ExpandableListConnector.java:445) 
10-16 15:15:44.011: E/AndroidRuntime(731):  at android.widget.AbsListView.obtainView(AbsListView.java:1315) 
10-16 15:15:44.011: E/AndroidRuntime(731):  at android.widget.ListView.makeAndAddView(ListView.java:1727) 
10-16 15:15:44.011: E/AndroidRuntime(731):  at android.widget.ListView.fillDown(ListView.java:652) 
10-16 15:15:44.011: E/AndroidRuntime(731):  at android.widget.ListView.fillFromTop(ListView.java:709) 
10-16 15:15:44.011: E/AndroidRuntime(731):  at android.widget.ListView.layoutChildren(ListView.java:1580) 
10-16 15:15:44.011: E/AndroidRuntime(731):  at android.widget.AbsListView.onLayout(AbsListView.java:1147) 
10-16 15:15:44.011: E/AndroidRuntime(731):  at android.view.View.layout(View.java:7035) 
10-16 15:15:44.011: E/AndroidRuntime(731):  at android.widget.RelativeLayout.onLayout(RelativeLayout.java:909) 
10-16 15:15:44.011: E/AndroidRuntime(731):  at android.view.View.layout(View.java:7035) 
10-16 15:15:44.011: E/AndroidRuntime(731):  at android.widget.FrameLayout.onLayout(FrameLayout.java:333) 
10-16 15:15:44.011: E/AndroidRuntime(731):  at android.view.View.layout(View.java:7035) 
10-16 15:15:44.011: E/AndroidRuntime(731):  at android.support.v4.view.ViewPager.onLayout(ViewPager.java:1589) 
10-16 15:15:44.011: E/AndroidRuntime(731):  at android.view.View.layout(View.java:7035) 
10-16 15:15:44.011: E/AndroidRuntime(731):  at android.widget.FrameLayout.onLayout(FrameLayout.java:333) 
10-16 15:15:44.011: E/AndroidRuntime(731):  at android.view.View.layout(View.java:7035) 
10-16 15:15:44.011: E/AndroidRuntime(731):  at android.widget.LinearLayout.setChildFrame(LinearLayout.java:1249) 
10-16 15:15:44.011: E/AndroidRuntime(731):  at android.widget.LinearLayout.layoutVertical(LinearLayout.java:1125) 
10-16 15:15:44.011: E/AndroidRuntime(731):  at android.widget.LinearLayout.onLayout(LinearLayout.java:1042) 
10-16 15:15:44.011: E/AndroidRuntime(731):  at android.view.View.layout(View.java:7035) 
10-16 15:15:44.011: E/AndroidRuntime(731):  at android.widget.FrameLayout.onLayout(FrameLayout.java:333) 
10-16 15:15:44.011: E/AndroidRuntime(731):  at android.view.View.layout(View.java:7035) 
10-16 15:15:44.011: E/AndroidRuntime(731):  at android.view.ViewRoot.performTraversals(ViewRoot.java:1045) 
10-16 15:15:44.011: E/AndroidRuntime(731):  at android.view.ViewRoot.handleMessage(ViewRoot.java:1727) 
10-16 15:15:44.011: E/AndroidRuntime(731):  at android.os.Handler.dispatchMessage(Handler.java:99) 
10-16 15:15:44.011: E/AndroidRuntime(731):  at android.os.Looper.loop(Looper.java:123) 
10-16 15:15:44.011: E/AndroidRuntime(731):  at android.app.ActivityThread.main(ActivityThread.java:4627) 
10-16 15:15:44.011: E/AndroidRuntime(731):  at java.lang.reflect.Method.invokeNative(Native Method) 
10-16 15:15:44.011: E/AndroidRuntime(731):  at java.lang.reflect.Method.invoke(Method.java:521) 
10-16 15:15:44.011: E/AndroidRuntime(731):  at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:868) 
10-16 15:15:44.011: E/AndroidRuntime(731):  at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:626)

10-16 15：15：44.011：E/AndroidRuntime（731）：在dalvik.system。 NativeStart.main（本地方法）

來源

2013-10-16 yuva ツ

你在哪裏得到空指針異常？你的logcat在哪裏？發佈logcat。 – GrIsHu

我在評論區塊中提到過我收到空指針異常 –

沒有人能夠通過評論來理解。發佈logcat有沒有問題？ – GrIsHu

通上下文適配器像如下─

listAdapter = new ExpandableListAdapter(getActivity(), listDataHeader, listDataChild);

來源

2013-10-16 10:13:22

從您的DemoActivity定義上下文爲mContext=DemoActivity.this.getActivity();不只是Context。

您必須使用getActivity()，它返回與片段關聯的活動。
該活動是一個上下文（因爲Activity擴展上下文）。

編輯：

在你的情況下做的，如下：

public DemoActivity(FragmentActivity context) { 
    this.mContext=context; 
}

來源

2013-10-16 07:16:06 GrIsHu

public DemoActivity（Context context）{this.mContext = context; } 這裏上下文是我從片段活動傳遞到這個片段類構造函數 –

看看我更新的答案。 – GrIsHu

這一個是我所做的 –

Exapandable listview不工作在android中的片段活動

回答

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