更改指标在ExpandableListView中的位置会导致问题

这是自定义可扩展列表视图的示例：

如果在新项目中应用此代码，您想看到的是：

将此代码创建为活动

public class ExpActivity extends Activity
{

    @Override
    public void onCreate(Bundle savedInstanceState)
    {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);

        // Находим наш list 
        ExpandableListView listView = (ExpandableListView)findViewById(R.id.exListView);

        //Создаем набор данных для адаптера        
        ArrayList<ArrayList<String>> groups = new ArrayList<ArrayList<String>>();
        ArrayList<String> children1 = new ArrayList<String>();
        ArrayList<String> children2 = new ArrayList<String>();
        children1.add("Child_1");
        children1.add("Child_2");
        groups.add(children1);
        children2.add("Child_1");
        children2.add("Child_2");
        children2.add("Child_3");
        groups.add(children2);       
       //Создаем адаптер и передаем context и список с данными
        ExpListAdapter adapter = new ExpListAdapter(getApplicationContext(), groups);
        listView.setAdapter(adapter);
    }
} 

将expandableListView添加到main.xml中

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:orientation="vertical"
    android:layout_width="fill_parent"
    android:layout_height="fill_parent"
    >
<ExpandableListView
        android:id="@+id/exListView"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:indicatorLeft="250dp"
        android:indicatorRight="300dp"
    />
</LinearLayout>

创建一个适配器类

public class ExpListAdapter extends BaseExpandableListAdapter {

    private ArrayList<ArrayList<String>> mGroups;
    private Context mContext;

    public ExpListAdapter (Context context,ArrayList<ArrayList<String>> groups){
        mContext = context;
        mGroups = groups;
    }

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

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

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

    @Override
    public Object getChild(int groupPosition, int childPosition) {
        return mGroups.get(groupPosition).get(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 getGroupView(int groupPosition, boolean isExpanded, View convertView,
                             ViewGroup parent) {

        if (convertView == null) {
            LayoutInflater inflater = (LayoutInflater) mContext.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
            convertView = inflater.inflate(R.layout.group_view, null);
        }

        if (isExpanded){
           //Изменяем что-нибудь, если текущая Group раскрыта
        }
        else{
            //Изменяем что-нибудь, если текущая Group скрыта
        }

        TextView textGroup = (TextView) convertView.findViewById(R.id.textGroup);
        textGroup.setText("Group " + Integer.toString(groupPosition));

        return convertView;

    }

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

        TextView textChild = (TextView) convertView.findViewById(R.id.textChild);
        textChild.setText(mGroups.get(groupPosition).get(childPosition));

        Button button = (Button)convertView.findViewById(R.id.buttonChild);
        button.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                Toast.makeText(mContext,"button is pressed",5000).show();
            }
        });

        return convertView;
    }

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

方法和参数的名称非常有用。方法getGroupView和getChildView返回p的Viewparents并children相应地返回。例如，使用方法getGroupView中的isExpanded参数，我们可以更改组的背面处于不同的状态。使用LayoutInflater，我们将自定义布局用于列表。

group_view.xml

<?xml version="1.0" encoding="utf-8"?>

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
              android:layout_width="match_parent"
              android:layout_height="match_parent">
    <TextView
            android:id="@+id/textGroup"
            android:layout_width="wrap_content"
            android:layout_height="50dp"
            android:layout_marginLeft="5dp"
            android:layout_marginTop="20dp"
            android:textColor="@android:color/white"
            android:textStyle="bold"
            />
</LinearLayout>

child_view.xml

<?xml version="1.0" encoding="utf-8"?>

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
              android:layout_width="match_parent"
              android:layout_height="match_parent">
  <TextView
     android:id="@+id/textChild"
     android:layout_width="wrap_content"
     android:layout_height="40dp"
     android:layout_marginLeft="20dp"
     android:layout_marginTop="20dp"
     android:textColor="@android:color/white"
     />
  <Button
     android:id="@+id/buttonChild"
     android:layout_width="100dp"
     android:layout_height="40dp"
     android:layout_marginLeft="150dp"
     android:layout_marginTop="10dp"
     android:text="Button"
     android:focusable="false"
     />
</LinearLayout>

在子视图中，我们在适配器方法getChildView中添加了一个按钮来控制其按下。以类似的方式，我们可以在group_view.xml中添加按钮和其他元素。

此外，我们可以将侦听器固定到我们的列表。

•OnChildClickListener-按下元素•OnGroupCollapseListener-折叠组•OnGroupExpandListener-展开组•OnGroupClickListener-按下组

现在让我们看看groupIndicater-组状态的指示器。它是在main.xml中指向的位置，其参数为indicatorLeft，indicatorRigh-对应于左边框和右边框。默认情况下，指示器位于左侧，不是很酷。

我们还可以添加自定义图像，为此，我们需要在可绘制此代码的文件夹中添加indicator.xml。

<?xml version="1.0" encoding="utf-8"?>

<selector xmlns:android="http://schemas.android.com/apk/res/android">
    <item android:state_expanded="true"
          android:drawable="@drawable/imageOpen">
    </item>
    <item android:state_empty="true"
          android:drawable="@drawable/imageClose">
    </item>
</selector>

其中imageOpen用于展开的组imageClose用于折叠的组

下次我们需要在main.xml中为列表的参数添加一行

android:groupIndicator="@drawable/indicator"