在android代碼中可擴展列表視圖

Question

**我想在我的android代碼的片段中添加可展開列表視圖，但我無法做到這一點。我也在這個網站上看到了與這個主題相關的所有帖子，但我找不到一個好的答案。任何人都可以幫忙嗎？ **

HMCfragment.java 
public class HMCfragment extends Fragment { 

View rootView; 
ExpandableListView lv; 
private String[] groups; 
private String[][] children; 

@Override 
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) { 
groups = new String[] { "Test Header 1", "Test Header 2", "Test Header 3", "Test Header 4" }; 
children = new String [][] {{"Debashish Dutta"},{"Deepok Baruah"},{"Rajan Kumar"},{"Aditya   Patel"},{"Piyush dwivedi"}}; 

rootView = inflater.inflate(R.layout.hmc_layout, container, false); 

return rootView; 
} 

@Override 
public void onViewCreated(View view, Bundle savedInstanceState) { 
super.onViewCreated(view, savedInstanceState); 

lv = (ExpandableListView) view.findViewById(R.id.expandableListView1); 
lv.setAdapter(new ExpandableListAdapter(groups, children)); 
lv.setGroupIndicator(null); 

} 

public class ExpandableListAdapter extends BaseExpandableListAdapter { 

private final LayoutInflater inf; 
private String[] groups; 
private String[][] children; 

public ExpandableListAdapter(String[] groups, String[][] children) { 
    this.groups = groups; 
    this.children = children; 
    inf = LayoutInflater.from(getActivity()); 
} 

@Override 
public int getGroupCount() { 
    return groups.length; 
} 

@Override 
public int getChildrenCount(int groupPosition) { 
    return children[groupPosition].length; 
} 

@Override 
public Object getGroup(int groupPosition) { 
    return groups[groupPosition]; 
} 

@Override 
public Object getChild(int groupPosition, int childPosition) { 
    return children[groupPosition][childPosition]; 
} 

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

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

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

@Override 
public View getChildView(int groupPosition, final int childPosition, boolean isLastChild, View convertView, ViewGroup parent) { 

    ViewHolder holder; 
     if (convertView == null) { 
      convertView = inf.inflate(R.layout.child_layout, parent, false); 
      holder = new ViewHolder(); 

      holder.text = (TextView) convertView.findViewById(R.id.textView1); 
      convertView.setTag(holder); 
     } else { 
      holder = (ViewHolder) convertView.getTag(); 
     } 

     holder.text.setText(getChild(groupPosition, childPosition).toString()); 

     return convertView; 
} 

@Override 
public View getGroupView(int groupPosition, boolean isExpanded, View convertView, ViewGroup parent) { 
    ViewHolder holder; 

    if (convertView == null) { 
     convertView = inf.inflate(R.layout.parent_layout, parent, false); 

     holder = new ViewHolder(); 
     holder.text = (TextView) convertView.findViewById(R.id.parent_txt); 
     convertView.setTag(holder); 
    } else { 
     holder = (ViewHolder) convertView.getTag(); 
    } 

    holder.text.setText(getGroup(groupPosition).toString()); 

    return convertView; 
} 

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

private class ViewHolder { 
    TextView text; 
} 

}}

Answer 1

這裏是我創建的項目;

MyActivity.java

public class MyActivity extends Activity { 

    @Override 
    protected void onCreate(Bundle savedInstanceState) { 
     super.onCreate(savedInstanceState); 
     setContentView(R.layout.activity_my); 
     if (savedInstanceState == null) { 
      getFragmentManager().beginTransaction() 
       .add(R.id.container, new PlaceholderFragment()) 
       .commit(); 
     } 
    } 

    /** 
    * A placeholder fragment containing a simple view. 
    */ 
    public static class PlaceholderFragment extends Fragment { 

     public PlaceholderFragment() { 
     } 

     View rootView; 
     ExpandableListView lv; 
     private String[] groups; 
     private String[][] children; 

     @Override 
     public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) { 
      groups = new String[]{"Test Header 1", "Test Header 2", "Test Header 3", "Test Header 4"}; 
      children = new String[][]{{"Debashish Dutta"}, {"Deepok Baruah"}, {"Rajan Kumar"}, {"Aditya   Patel"}, {"Piyush dwivedi"}}; 

      rootView = inflater.inflate(R.layout.fragment_my, container, false); 

      return rootView; 
     } 

     @Override 
     public void onViewCreated(View view, Bundle savedInstanceState) { 
      super.onViewCreated(view, savedInstanceState); 

      lv = (ExpandableListView) view.findViewById(R.id.exp); 
      lv.setAdapter(new ExpandableListAdapter(groups, children)); 
      lv.setGroupIndicator(null); 

     } 

     public class ExpandableListAdapter extends BaseExpandableListAdapter { 

      private final LayoutInflater inf; 
      private String[] groups; 
      private String[][] children; 

      public ExpandableListAdapter(String[] groups, String[][] children) { 
       this.groups = groups; 
       this.children = children; 
       inf = LayoutInflater.from(getActivity()); 
      } 

      @Override 
      public int getGroupCount() { 
       return groups.length; 
      } 

      @Override 
      public int getChildrenCount(int groupPosition) { 
       return children[groupPosition].length; 
      } 

      @Override 
      public Object getGroup(int groupPosition) { 
       return groups[groupPosition]; 
      } 

      @Override 
      public Object getChild(int groupPosition, int childPosition) { 
       return children[groupPosition][childPosition]; 
      } 

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

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

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

      @Override 
      public View getChildView(int groupPosition, final int childPosition, boolean isLastChild, View convertView, ViewGroup parent) { 

       ViewHolder holder; 
       if (convertView == null) { 
        convertView = inf.inflate(R.layout.child_layout, parent, false); 
        holder = new ViewHolder(); 

        holder.text = (TextView) convertView.findViewById(R.id.textView); 
        convertView.setTag(holder); 
       } else { 
        holder = (ViewHolder) convertView.getTag(); 
       } 

       holder.text.setText(getChild(groupPosition, childPosition).toString()); 

       return convertView; 
      } 

      @Override 
      public View getGroupView(int groupPosition, boolean isExpanded, View convertView, ViewGroup parent) { 
       ViewHolder holder; 

       if (convertView == null) { 
        convertView = inf.inflate(R.layout.parent_layout, parent, false); 

        holder = new ViewHolder(); 
        holder.text = (TextView) convertView.findViewById(R.id.textView); 
        convertView.setTag(holder); 
       } else { 
        holder = (ViewHolder) convertView.getTag(); 
       } 

       holder.text.setText(getGroup(groupPosition).toString()); 

       return convertView; 
      } 

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

      private class ViewHolder { 
       TextView text; 
      } 
     } 
    } 
} 

fragment_my.xml

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android" 
    xmlns:tools="http://schemas.android.com/tools" 
    android:layout_width="match_parent" 
    android:layout_height="match_parent" 
    android:paddingLeft="@dimen/activity_horizontal_margin" 
    android:paddingRight="@dimen/activity_horizontal_margin" 
    android:paddingTop="@dimen/activity_vertical_margin" 
    android:paddingBottom="@dimen/activity_vertical_margin" 
    tools:context=".MyActivity$PlaceholderFragment"> 

    <ExpandableListView 
     android:id="@+id/exp" 
     android:layout_width="match_parent" 
     android:layout_height="match_parent"/> 

</RelativeLayout> 

child_layout.xml

<?xml version="1.0" encoding="utf-8"?> 
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android" 
    android:orientation="vertical" android:layout_width="match_parent" 
    android:layout_height="match_parent"> 

    <TextView 
     android:layout_width="wrap_content" 
     android:layout_height="wrap_content" 
     android:text="New Text" 
     android:id="@+id/textView" 
     android:layout_gravity="center_horizontal" /> 
</LinearLayout> 

parent_layout.xml

<?xml version="1.0" encoding="utf-8"?> 
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android" 
    android:orientation="vertical" android:layout_width="match_parent" 
    android:layout_height="match_parent"> 

    <TextView 
     android:layout_width="wrap_content" 
     android:layout_height="wrap_content" 
     android:text="New Text" 
     android:id="@+id/textView" 
     android:layout_gravity="center_horizontal" /> 
</LinearLayout>