在ListView中沒有添加子項目

Question

我想爲我的Android應用程序的ListView中的每個項目添加子項目。爲此我寫了這段代碼（下面給出）。但是這不起作用。我是Android新手，我看到很多解決這個問題的例子，但他們沒有幫助。所以請告訴我如何在我的ListView中添加每件商品的子商品。

ListDisplay.java

public class ListDisplay extends AppCompatActivity { 

    String[] items = {"Android","IPhone","WindowsMobile","Blackberry","WebOS","Ubuntu","Windows7","Max OS X"}; 
    String[] subItems = {"lollipop","4s","8.1","a1","os","ubnt","7","air"}; 

    public static ListView listView; 

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

     listView = (ListView) findViewById(R.id.listViewItems); 
     ArrayAdapter adapter = new ArrayAdapter<String>(context, R.layout.activity_listview, items, subItems); 
     ListDisplay.listView.setAdapter(adapter); 
    } 

} 

activity_listview.xml

<?xml version="1.0" encoding="utf-8"?> 
<!-- Single List Item Design --> 

<TextView xmlns:android="http://schemas.android.com/apk/res/android" 
    android:id="@+id/label" 
    android:layout_width="fill_parent" 
    android:layout_height="fill_parent" 
    android:padding="10dip" 
    android:textSize="16dip" 
    android:textStyle="bold" > 
</TextView> 

content_list_display.xml

<?xml version="1.0" encoding="utf-8"?> 
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android" 
    xmlns:app="http://schemas.android.com/apk/res-auto" 
    xmlns:tools="http://schemas.android.com/tools" 
    android:layout_width="match_parent" 
    android:layout_height="match_parent" 
    android:paddingBottom="@dimen/activity_vertical_margin" 
    android:paddingLeft="@dimen/activity_horizontal_margin" 
    android:paddingRight="@dimen/activity_horizontal_margin" 
    android:paddingTop="@dimen/activity_vertical_margin" 
    app:layout_behavior="@string/appbar_scrolling_view_behavior" 
    tools:context="com.example.abc.project1.ListDisplay" 
    tools:showIn="@layout/activity_list_display"> 

    <ListView 
     android:layout_width="wrap_content" 
     android:layout_height="wrap_content" 
     android:id="@+id/listViewItems" 
     android:layout_alignParentRight="true" 
     android:layout_alignParentEnd="true" 
     android:layout_alignParentTop="true" /> 
</RelativeLayout> 

Answer 1

您需要爲此製作一個自定義適配器。這是你應該使用的代碼。

/** class to act as list adapter for rows List */ 
private static class TwoTextListAdapter extends ArrayAdapter<MyDataClass> { 

    /** To cache views of item */ 
    private static class ViewHolder { 
     private TextView label; 
     private TextView subLabel; 

     /** 
     * General constructor 
     */ 
     ViewHolder() { 
      // nothing to do here 
     } 
    } 

    /** Inflater for list items */ 
    private final LayoutInflater inflater; 

    /** 
    * General constructor 
    * 
    * @param context 
    * @param resource 
    * @param textViewResourceId 
    * @param objects 
    */ 
    public TwoTextListAdapter(final Context context, 
      final int resource, 
      final int textViewResourceId, 
      final List<User> objects) { 
     super(context, resource, textViewResourceId, objects); 

     this.inflater = LayoutInflater.from(context); 
    } 

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

     View itemView = convertView; 
     ViewHolder holder = null; 
     final MyDataClass item = getItem(position); 

     if(null == itemView) { 
      itemView = this.inflater.inflate(R.layout.activity_listviewpar, parent, false); 

      holder = new ViewHolder(); 

      holder.label = (TextView)itemView.findViewById(R.id.label); 
      holder.subLabel = (TextView)itemView.findViewById(R.id.subLabel); 

      itemView.setTag(holder); 
     } else { 
      holder = (ViewHolder)itemView.getTag(); 
     } 

     holder.label.setText(item.getlabel()); 
     holder.subLabel.setText(item.getsubLabel()); 

     return itemView; 
    } 
} 

activity_listview.xml應該是這樣的

<LinearLayout 
    android:layout_width="match_parent" 
    android:layout_height="match_parent" 
    android:orientation="vertical"> 
<TextView xmlns:android="http://schemas.android.com/apk/res/android" 
    android:id="@+id/label" 
    android:layout_width="fill_parent" 
    android:layout_height="fill_parent" 
    android:padding="10dip" 
    android:textSize="16dip" 
    android:textStyle="bold" > 
</TextView> 
<TextView xmlns:android="http://schemas.android.com/apk/res/android" 
    android:id="@+id/subLabel" 
    android:layout_width="fill_parent" 
    android:layout_height="fill_parent" 
    android:padding="10dip" 
    android:textSize="16dip" 
    android:textStyle="bold" > 
</TextView> 
</LinearLayout> 

最後在ListDisplay做到這一點

public class ListDisplay extends AppCompatActivity { 

    String[] items = {"Android","IPhone","WindowsMobile","Blackberry","WebOS","Ubuntu","Windows7","Max OS X"}; 
    String[] subItems = {"lollipop","4s","8.1","a1","os","ubnt","7","air"}; 

    public static ListView listView; 
    public List<Item> list = new ArrayList<>(); 

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

     for(int i=0;i<items.length;i++){ 
      list.add(new Item(items[i],subItems[i])) 
     } 

     listView = (ListView) findViewById(R.id.listViewItems); 
     TwoTextListAdapter adapter = new TwoTextListAdapter(context, R.layout.activity_listview, null, list); 
     ListDisplay.listView.setAdapter(adapter); 
    } 

    public class Item { 
     public String a,b; 

     public Item(String a, String b) { 
      this.a = a; 
      this.b = b; 
     } 
    } 

}