ExpandableListView使用技巧与总结

本文将介绍系统控件ExpandableListView的简要使用，主要学习了系统提供的二级菜单列表的实现方式。学习了指示展示效果。

效果1:

 如下，修改了指示器的排列位置，列表左侧，现在修改为列表右侧。主要是设置android:layoutDirection 设置排列方式即能达到特定的效果。

    <ExpandableListView
        android:layoutDirection="rtl"
        android:id="@+id/expandListView"
        android:layout_width="match_parent"
        android:layout_height="match_parent">
    </ExpandableListView>

// item_parent
<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout
    xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layoutDirection="ltr"
    android:layout_height="45dp">
    ....
</RelativeLayout>

// item_child
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout
    xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:orientation="horizontal"
    android:layoutDirection="ltr"
    android:layout_height="60dp">
</LinearLayout>

效果2:

其实我只是想修改下指示的下标罢了,可是图标会拉伸很丑啊。暂时不知道为啥自己设置的groupInficator会是变形的，知道的大神请告知。尝试过设置.9图并没有什么用处。

    <ExpandableListView
        android:layoutDirection="rtl"
        android:id="@+id/expandListView"
        android:groupIndicator="@drawable/expand_group_indicator"
        android:layout_width="match_parent"
        android:layout_height="match_parent">
    </ExpandableListView>

<?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/shape_right"/>
    <item android:drawable="@drawable/shape_bottom"/>
</selector>

效果3: 完全自定义的指示图标

好了下面开始贴代码咯，啧啧

核心adapter

public class EpLvOneAdapter extends BaseExpandableListAdapter{
    private List<EpLvOneBean> mEpLvOneBeanList;
    private Context mContext;
    private SparseArray<ImageView> mIndicators = new SparseArray<>();

    public EpLvOneAdapter(Context context,List<EpLvOneBean> epLvOneBeanList) {
        mEpLvOneBeanList = epLvOneBeanList;
        mContext = context;
    }

    @Override
    public int getGroupCount() {
        if (mEpLvOneBeanList != null){
            return mEpLvOneBeanList.size();
        }
        return 0;
    }

    @Override
    public int getChildrenCount(int groupPosition) {
        if (mEpLvOneBeanList != null){
            EpLvOneBean epLvOneBean = mEpLvOneBeanList.get(groupPosition);
            if (null != epLvOneBean &&  null != epLvOneBean.getEpOneChildBeans()){
                return epLvOneBean.getEpOneChildBeans().size();
            }
        }
        return 0;
    }

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

    @Override
    public Object getChild(int groupPosition, int childPosition) {
        if ( null != mEpLvOneBeanList.get(groupPosition).getEpOneChildBeans()){
            return mEpLvOneBeanList.get(groupPosition).getEpOneChildBeans().get(childPosition);
        }
        return null;
    }

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

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

    //每个item的id是否是固定？一般为true
    @Override
    public boolean hasStableIds() {
        return true;
    }

    @Override
    public View getGroupView(int groupPosition, boolean isExpanded, View convertView, ViewGroup parent) {
        GroupViewHolder groupViewHolder;
        if (null == convertView){
            groupViewHolder = new GroupViewHolder();
            convertView = LayoutInflater.from(mContext).inflate(R.layout.item_one_group,parent,false);
            groupViewHolder.tvGroupName = convertView.findViewById(R.id.tvGroupName);
            groupViewHolder.tvGroupNum = convertView.findViewById(R.id.tvGroupNum);
            groupViewHolder.ivIndicator = convertView.findViewById(R.id.ivIndicator);
            convertView.setTag(groupViewHolder);
        }else {
            groupViewHolder = (GroupViewHolder) convertView.getTag();
        }
        EpLvOneBean epLvOneBean = mEpLvOneBeanList.get(groupPosition);
        groupViewHolder.tvGroupName.setText(epLvOneBean.getName());
        if (null != epLvOneBean.getEpOneChildBeans()) {
            groupViewHolder.tvGroupNum.setText(String.valueOf(epLvOneBean.getEpOneChildBeans().size()));
        }else {
            groupViewHolder.tvGroupNum.setText("0");
        }
        if (mIndicators.get(groupPosition) == null) {
            mIndicators.put(groupPosition, groupViewHolder.ivIndicator);
        }
        setIndicatorState(groupPosition, isExpanded);
        return convertView;
    }

    public void setIndicatorState(int groupPosition, boolean isExpanded) {
        if (isExpanded) {
            mIndicators.get(groupPosition).setImageResource(R.drawable.shape_bottom);
        } else {
            mIndicators.get(groupPosition).setImageResource(R.drawable.shape_right);
        }
    }

    @Override
    public View getChildView(int groupPosition, int childPosition, boolean isLastChild, View convertView, ViewGroup parent) {
        EpOneChildBean epOneChildBean = mEpLvOneBeanList.get(groupPosition).getEpOneChildBeans().get(childPosition);
        ChildViewHolder childViewHolder;
        if (null == convertView){
            childViewHolder = new ChildViewHolder();
            convertView = LayoutInflater.from(mContext).inflate(R.layout.item_one_child,parent,false);
            childViewHolder.tvChildName = convertView.findViewById(R.id.tvChildName);
            childViewHolder.tvChildState = convertView.findViewById(R.id.tvChildState);
            convertView.setTag(childViewHolder);
        }else {
            childViewHolder = (ChildViewHolder) convertView.getTag();
        }

        childViewHolder.tvChildName.setText(epOneChildBean.getChildName());
        childViewHolder.tvChildState.setText(epOneChildBean.getChildState());
        return convertView;
    }

    //二级列表中的item是否能够被选中？可以改为true
    @Override
    public boolean isChildSelectable(int groupPosition, int childPosition) {
        return true;
    }

    static class GroupViewHolder{
        TextView tvGroupName;
        TextView tvGroupNum;
        ImageView ivIndicator;
    }

    static class ChildViewHolder{
        TextView tvChildName;
        TextView tvChildState;
    }
}

 item_one_group.xml 设置下拉图标的布局

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout
    xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layoutDirection="ltr"
    android:layout_height="45dp">
    <TextView
        android:id="@+id/tvGroupName"
        android:text="特别关心"
        android:textColor="#000"
        android:layout_centerVertical="true"
        android:textSize="16sp"
        android:layout_marginLeft="6dp"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content" />
    <TextView
        android:id="@+id/tvGroupNum"
        android:text="6"
        android:layout_alignParentRight="true"
        android:layout_centerVertical="true"
        android:layout_marginRight="45dp"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content" />

    <ImageView
        android:layout_alignParentRight="true"
        android:id="@+id/ivIndicator"
        android:visibility="visible"
        android:layout_marginRight="15dp"
        android:layout_centerVertical="true"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_gravity="center_vertical"
        android:src="@drawable/shape_right"/>

</RelativeLayout>

group点击事件

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        expandListView.setOnGroupClickListener(new ExpandableListView.OnGroupClickListener() {
            @Override
            public boolean onGroupClick(ExpandableListView parent, View v, int groupPosition, long id) {
                boolean groupExpanded = parent.isGroupExpanded(groupPosition);
                if (groupExpanded) {
                    parent.collapseGroup(groupPosition);
                } else {
                    parent.expandGroup(groupPosition, true);
                }
                mEpLvOneAdapter.setIndicatorState(groupPosition, groupExpanded);
                return true;
            }
        });

列表数据类型

public class EpLvOneBean {
    private String name;
    private List<EpOneChildBean> mEpOneChildBeans;

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public List<EpOneChildBean> getEpOneChildBeans() {
        return mEpOneChildBeans;
    }

    public void setEpOneChildBeans(List<EpOneChildBean> epOneChildBeans) {
        mEpOneChildBeans = epOneChildBeans;
    }
}


public class EpOneChildBean {
    private String childName;
    private String childState;

    public String getChildName() {
        return childName;
    }

    public void setChildName(String childName) {
        this.childName = childName;
    }

    public String getChildState() {
        return childState;
    }

    public void setChildState(String childState) {
        this.childState = childState;
    }

    public EpOneChildBean(String childName, String childState) {
        this.childName = childName;
        this.childState = childState;
    }
}

4. 技巧---默认展开且不可收缩 

        // 设置不可点击
        expandListView.setOnGroupClickListener(new ExpandableListView.OnGroupClickListener() {
            @Override
            public boolean onGroupClick(ExpandableListView parent, View v, int groupPosition, long id) {
                return true;
            }
        });

        // 设置默认展开
        int count = expandListView.getCount();
        for (int i=0;i<count;i++){
            expandListView.expandGroup(i);
        }

 参考资料:安卓的ExpandableListView的使用和优化

                Android ExpandableListView使用小结

不错的recycle展开资料

                Android -- RecyclerView（超简单）实现可展开列表