Android ExpandableListView

Android ExpandableListView

控件的使用

<?xml version="1.0" encoding="utf-8"?>
<androidx.constraintlayout.widget.ConstraintLayout 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"
    tools:context=".MainActivity">

    <ExpandableListView
        android:id="@+id/expand_lv"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toTopOf="parent" />

</androidx.constraintlayout.widget.ConstraintLayout>

首先，添加ExpandableListView到主页面中。

数据源设置

//用于 Item Group 数据源
private List<String> lsGroupData = new ArrayList<>();
//用于 Item Child 数据源
private List<List<String>> lsChildGroup = new ArrayList<>();

// 初始换数据
private void initData() {
    int groupCount = 10;
    for (int i = 0; i < groupCount; i++) {
        lsGroupData.add("Item - " + i);
        int childCount = new Random().nextInt(30);
        List<String> lsChildData = new ArrayList<>();
        for (int i1 = 0; i1 < childCount; i1++) {
            lsChildData.add("item - " + i + " - " + i1);
        }
        lsChildGroup.add(lsChildData);
    }
}

适配器 代码

public class MyAdapter extends BaseExpandableListAdapter {
    private Context context;
    private List<String> lsGroupData;
    private List<List<String>> lsChildData;
    /**
     * 构造函数
     * @param context
     * @param lsGroupData 存储 关于 Item Group的全部数据
     * @param lsChildData 存储关于 Item Child的全部数据
     */
    MyAdapter(Context context, List<String> lsGroupData, List<List<String>> lsChildData) {
        this.context = context;
        this.lsGroupData = lsGroupData;
        this.lsChildData = lsChildData;
    }
    /**
     * 获取 Group 大小
     * @return
     */
    @Override
    public int getGroupCount() {
        return lsGroupData.size();
    }
    /**
     * 获取 Child 大小
     * @param groupPosition
     * @return
     */
    @Override
    public int getChildrenCount(int groupPosition) {
        return lsChildData.get(groupPosition).size();
    }
    /**
     * 获取 指定 Position 下的Group 数据
     * @param groupPosition
     * @return
     */
    @Override
    public Object getGroup(int groupPosition) {
        return lsGroupData.get(groupPosition);
    }
    /**
     * 获取 指定 Position 下的Child 数据
     * @param groupPosition
     * @param childPosition
     * @return
     */
    @Override
    public Object getChild(int groupPosition, int childPosition) {
        return lsChildData.get(groupPosition).get(childPosition);
    }
    /**
     * 获取Group ID
     * @param groupPosition
     * @return
     */
    @Override
    public long getGroupId(int groupPosition) {
        return groupPosition;
    }
    /**
     * 获取Child ID
     * @param groupPosition
     * @param childPosition
     * @return
     */
    @Override
    public long getChildId(int groupPosition, int childPosition) {
        return childPosition;
    }
    /**
     * 具有稳定的ID
     * @return
     */
    @Override
    public boolean hasStableIds() {
        return false;
    }
    /**
     * 获取 Group 项的 View
     * @param groupPosition
     * @param isExpanded
     * @param convertView
     * @param parent
     * @return
     */
    @Override
    public View getGroupView(int groupPosition, boolean isExpanded, View convertView, ViewGroup parent) {
        if (convertView == null) {
            convertView = LayoutInflater.from(context).inflate(R.layout.item_group, null);
        }
        TextView txtGroupName = convertView.findViewById(R.id.txtGroupName);
        txtGroupName.setText(lsGroupData.get(groupPosition));
        TextView txtItemCount = convertView.findViewById(R.id.txtItemsCount);
        txtItemCount.setText(String.valueOf(lsChildData.get(groupPosition).size()));
        return convertView;
    }
    /**
     * 获取 Child 项的 View
     * @param groupPosition
     * @param childPosition
     * @param isLastChild
     * @param convertView
     * @param parent
     * @return
     */
    @Override
    public View getChildView(final int groupPosition, final int childPosition, boolean isLastChild, View convertView, ViewGroup parent) {
        if (convertView == null) {
            convertView = LayoutInflater.from(context).inflate(R.layout.item_child, null);
        }
        TextView txtChildName = convertView.findViewById(R.id.txtItemName);
        txtChildName.setText(lsChildData.get(groupPosition).get(childPosition));
        txtChildName.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                Toast.makeText(context, lsChildData.get(groupPosition).get(childPosition), Toast.LENGTH_SHORT).show();
            }
        });
        return convertView;
    }
    @Override
    public boolean isChildSelectable(int groupPosition, int childPosition) {
        return true;
    }
}

这部分就是适配器代码。

我们来分析一下：

首先，我们将我们的适配器类继承与BaseExpandableListAdapter

然后重写如下方法：

我们重写下面所有的方法。

相关的方法注释在上面的代码中由具体写到。

最后，我们来看一下效果图：

这样，ExpandableListView的使用就到这里了。

本控件学习自：https://www.jianshu.com/p/8bc7c8e97afc