ExpandableListView

1. 简介

看下源码中的英文介绍

/**
* A view that shows items in a vertically scrolling two-level list. This
* differs from the {@link ListView} by allowing two levels: groups which can
* individually be expanded to show its children. The items come from the
* {@link ExpandableListAdapter} associated with this view.
*

* Expandable lists are able to show an indicator beside each item to display
* the item’s current state (the states are usually one of expanded group,
* collapsed group, child, or last child). Use
* {@link #setChildIndicator(Drawable)} or {@link #setGroupIndicator(Drawable)}
* (or the corresponding XML attributes) to set these indicators (see the docs
* for each method to see additional state that each Drawable can have). The
* default style for an {@link ExpandableListView} provides indicators which
* will be shown next to Views given to the {@link ExpandableListView}. The
* layouts android.R.layout.simple_expandable_list_item_1 and
* android.R.layout.simple_expandable_list_item_2 (which should be used with
* {@link SimpleCursorTreeAdapter}) contain the preferred position information
* for indicators.
*

* The context menu information set by an {@link ExpandableListView} will be a
* {@link ExpandableListContextMenuInfo} object with
* {@link ExpandableListContextMenuInfo#packedPosition} being a packed position
* that can be used with {@link #getPackedPositionType(long)} and the other
* similar methods.
*

* Note: You cannot use the value wrap_content
* for the android:layout_height attribute of a
* ExpandableListView in XML if the parent’s size is also not strictly specified
* (for example, if the parent were ScrollView you could not specify
* wrap_content since it also can be any length. However, you can use
* wrap_content if the ExpandableListView parent has a specific size, such as
* 100 pixels.
*
* @attr ref android.R.styleable#ExpandableListView_groupIndicator
* @attr ref android.R.styleable#ExpandableListView_indicatorLeft
* @attr ref android.R.styleable#ExpandableListView_indicatorRight
* @attr ref android.R.styleable#ExpandableListView_childIndicator
* @attr ref android.R.styleable#ExpandableListView_childIndicatorLeft
* @attr ref android.R.styleable#ExpandableListView_childIndicatorRight
* @attr ref android.R.styleable#ExpandableListView_childDivider
* @attr ref android.R.styleable#ExpandableListView_indicatorStart
* @attr ref android.R.styleable#ExpandableListView_indicatorEnd
* @attr ref android.R.styleable#ExpandableListView_childIndicatorStart
* @attr ref android.R.styleable#ExpandableListView_childIndicatorEnd
*/

ExpandableListView是不同于ListView的两级列表View，可以收起可以展开。通过ExpandableListAdapter来配置需要现实的items。

2. 基本使用

2.1 布局文件

group.xml(一级节点item布局)

<?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="wrap_content"
    android:paddingLeft="30dp"
    android:orientation="vertical" >
    <TextView
        android:id="@+id/group_text"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:paddingTop="10dip"
        android:paddingBottom="10dip"
        android:text=""
        />
</LinearLayout>

child.xml(二级节点item)

<?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"
    android:orientation="horizontal"
    android:paddingLeft="40dp">

    <TextView
        android:id="@+id/textOne"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:text="" />
</LinearLayout>

actiivty_main.xml(主界面布局)

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout 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"
    tools:context="cn.onlyloveyd.expandablelistviewdemo.MainActivity">


    <ExpandableListView
        android:id="@+id/expandable_list"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:groupIndicator="@drawable/expand"
        android:childIndicator="@drawable/collapse"
        />

</LinearLayout>

2.2 代码

YEAdapter.java(可伸展列表对应的Adapter)

public class YEAdapter extends BaseExpandableListAdapter {

    //一级节点数据
    private List<GroupItem> mGroupItems;
    private Context mContext;

    public YEAdapter(Context context, List<GroupItem> mData) {
        mGroupItems = mData;
        mContext = context;
    }

    /**
     * 一级节点数量
     * @return
     */
    @Override
    public int getGroupCount() {
        return mGroupItems.size();
    }

    /**
     * 指定位置一级节点下二级节点数量
     * @param groupPosition
     * @return
     */
    @Override
    public int getChildrenCount(int groupPosition) {
        return mGroupItems.get(groupPosition).mChildList.size();
    }

    /**
     * 获取一级节点对象
     * @param groupPosition
     * @return
     */
    @Override
    public Object getGroup(int groupPosition) {
        return mGroupItems.get(groupPosition);
    }

    /**
     * 获取二级节点对象
     * @param groupPosition
     * @param childPosition
     * @return
     */
    @Override
    public Object getChild(int groupPosition, int childPosition) {
        return mGroupItems.get(groupPosition).mChildList.get(childPosition);
    }

    /**
     * 获取一级节点ID，这里用位置值表示
     * @param groupPosition
     * @return
     */
    @Override
    public long getGroupId(int groupPosition) {
        return groupPosition;
    }

    /**
     * 获取二级节点ID，这里用位置值表示
     * @param groupPosition
     * @param childPosition
     * @return
     */
    @Override
    public long getChildId(int groupPosition, int childPosition) {
        return childPosition;
    }

    /**
     * ID是否稳定
     * @return
     */
    @Override
    public boolean hasStableIds() {
        return true;
    }

    /**
     * 获取一级节点view
     * @param groupPosition
     * @param isExpanded
     * @param convertView
     * @param parent
     * @return
     */
    @Override
    public View getGroupView(int groupPosition, boolean isExpanded, View convertView, ViewGroup parent) {
        View view=null;
        TextView mTv;
        if(convertView!=null){
            view = convertView;
            mTv = (TextView) view.getTag();
        }else{
            view = View.inflate(mContext,R.layout.group, null);
            mTv = (TextView) view.findViewById(R.id.group_text);
            view.setTag(mTv);
        }
        mTv.setText(mGroupItems.get(groupPosition).title);
        return view;
    }


    /**
     * 获取二级节点View
     * @param groupPosition
     * @param childPosition
     * @param isLastChild
     * @param convertView
     * @param parent
     * @return
     */
    @Override
    public View getChildView(int groupPosition, int childPosition, boolean isLastChild, View convertView, ViewGroup parent) {
        View view=null;
        TextView mTextView;
        if(convertView!=null){
            view = convertView;
            mTextView = (TextView) view.getTag();
        }else{
            view = View.inflate(mContext,R.layout.child, null);
            mTextView = (TextView) view.findViewById(R.id.textOne);
            view.setTag(mTextView);
        }
        mTextView.setText(mGroupItems.get(groupPosition).mChildList.get(childPosition).message);
        return view;
    }

    /**
     * 二级菜单是否可选（true为可选，false为不可选，也就是响应和不响应点击事件）
     * @param groupPosition
     * @param childPosition
     * @return
     */
    @Override
    public boolean isChildSelectable(int groupPosition, int childPosition) {
        return true;
    }

    /**
     * 一级节点对象
     */
    public static class GroupItem {
        String title;
        List<ChildItem> mChildList;
    }

    /**
     * 二级节点对象
     */
    public static class ChildItem {
        String message;
    }
}

具体解释请查阅注释信息

MainActivity.java

public class MainActivity extends AppCompatActivity {

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

        List<YEAdapter.GroupItem> mGroupItems = new ArrayList<>();
        for (int i = 0; i < 5; i++) {
            YEAdapter.GroupItem item = new YEAdapter.GroupItem();
            item.title = "this is " + i + "nd group item";
            List<YEAdapter.ChildItem> mChildItems = new ArrayList<>();
            for (int j = 0; j < 4; j++) {
                YEAdapter.ChildItem item1 = new YEAdapter.ChildItem();
                item1.message = "this is " + i + "nd group item's " + j + "nd child";
                mChildItems.add(item1);
            }
            item.mChildList = mChildItems;
            mGroupItems.add(item);
        }


        ExpandableListView expandableListView = (ExpandableListView) this.findViewById(R.id.expandable_list);

        YEAdapter yeAdapter = new YEAdapter(this, mGroupItems);
        expandableListView.setAdapter(yeAdapter);

        expandableListView.setOnChildClickListener(new ExpandableListView.OnChildClickListener() {
            @Override
            public boolean onChildClick(ExpandableListView parent, View v, int groupPosition, int childPosition, long id) {
                Toast.makeText(MainActivity.this,  groupPosition + "nd group's " + childPosition + "nd Item is clicked!", Toast.LENGTH_SHORT).show();
                return false;
            }
        });

        expandableListView.setOnGroupClickListener(new ExpandableListView.OnGroupClickListener() {
            @Override
            public boolean onGroupClick(ExpandableListView parent, View v, int groupPosition, long id) {
                Toast.makeText(MainActivity.this, groupPosition + "nd group is clicked", Toast.LENGTH_SHORT).show();
                return false;
            }
        });

        expandableListView.setOnGroupCollapseListener(new ExpandableListView.OnGroupCollapseListener() {
            @Override
            public void onGroupCollapse(int groupPosition) {
                Toast.makeText(MainActivity.this, "the " + groupPosition + "nd group is collapsed", Toast.LENGTH_SHORT).show();

            }
        });

        expandableListView.setOnGroupExpandListener(new ExpandableListView.OnGroupExpandListener() {
            @Override
            public void onGroupExpand(int groupPosition) {
                Toast.makeText(MainActivity.this, "the " + groupPosition + "nd group is expanded", Toast.LENGTH_SHORT).show();

            }
        });
    }
}

2.3 实际效果

3. 类结构

3.1 属性值

主要看看分割线效果
设置图片
divider.xml

<?xml version="1.0" encoding="utf-8"?>
<shape xmlns:android="http://schemas.android.com/apk/res/android">
    <solid
        android:color="@color/colorAccent"/>
    <corners
        android:radius="3dp"/>
</shape>

设置颜色
android:childDivider=”@color/colorPrimary”

那么一级节点如何设置分割线?
看这个例子

        android:childDivider="@color/colorPrimary"
        android:divider="@drawable/divider"
        android:dividerHeight="2dp"

给一级菜单和二级菜单设置不同的分割线，看下效果

二级节点依然显示的时我们设置的分割线，但是当一级节点展开时，展开的节点的一级分割线变成了二级节点的分割线样式，收起后恢复成一级节点的分割线样式。

3.2 常用方法

具体内容请查阅源码。

4. 设置上下文菜单

4.1 expandable_menu.xml

<?xml version="1.0" encoding="utf-8"?>
<menu xmlns:android="http://schemas.android.com/apk/res/android" >
    <item
        android:id="@+id/menu_item1"
        android:title="菜单项1">
    </item>
    <item
        android:id="@+id/menu_item2"
        android:title="菜单项2">
    </item>

</menu>

4.2 onCreateContextMenu

    @Override
    public void onCreateContextMenu(ContextMenu menu, View v, ContextMenu.ContextMenuInfo menuInfo) {
        super.onCreateContextMenu(menu, v, menuInfo);
        menu.setHeaderTitle("expandable menu");
        getMenuInflater().inflate(R.menu.expandable_menu, menu);
    }

4.3 onContextItemSelected

    @Override
    public boolean onContextItemSelected(MenuItem item) {
        // TODO Auto-generated method stub
        super.onContextItemSelected(item);
        switch (item.getItemId()) {
            case R.id.menu_item1:
                Toast.makeText(this, "this is first menu item", Toast.LENGTH_SHORT).show();
                break;
            case R.id.menu_item2:
                Toast.makeText(this, "this is second menu item", Toast.LENGTH_SHORT).show();
                break;
            default:
                break;
        }
        return super.onContextItemSelected(item);
    }

4.4 item长按事件显示菜单并注册上下文菜单

        expandableListView.setOnItemLongClickListener(new AdapterView.OnItemLongClickListener() {
            @Override
            public boolean onItemLongClick(AdapterView<?> parent, View view, int position, long id) {
                if (ExpandableListView.getPackedPositionType(id) == ExpandableListView.PACKED_POSITION_TYPE_CHILD)
                {
                    expandableListView.showContextMenu();
                    return true;
                }
                return false;
            }
        });
        registerForContextMenu(expandableListView);

5. 备注

程序源码