第49章、可伸缩列表ExpandableListView（从零开始学Android）

　　如果希望展示的列表可以收缩和展开，就像QQ好友列表一样，我们可以使用ExpandableListView。

 

一、设计界面

　　1、布局文件

　　打开activity_main.xml文件。

　　输入以下代码：

<?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="vertical" >     <ExpandableListView          android:id="@+id/province"         android:layout_width="match_parent"         android:layout_height="match_parent"         android:background="#EFEFEF">     </ExpandableListView>  </LinearLayout>

 

二、程序文件

　　打开“src/com.genwoxue.expandable/MainActivity.java”文件。

　　然后输入以下代码：

package com.genwoxue.expandablelistview;import android.app.Activity;import android.graphics.Color;import android.os.Bundle;import android.view.Gravity;import android.view.View;import android.view.ViewGroup;import android.widget.AbsListView;import android.widget.BaseExpandableListAdapter;import android.widget.ExpandableListAdapter;import android.widget.ExpandableListView;import android.widget.ExpandableListView.OnChildClickListener;import android.widget.LinearLayout;import android.widget.TextView;import android.widget.Toast;public class MainActivity extends Activity {    protected void onCreate(Bundle savedInstanceState) {        super.onCreate(savedInstanceState);        setContentView(R.layout.activity_main);        final ExpandableListAdapter adapter = new BaseExpandableListAdapter() {            //设置组视图的显示文字            private String[] province = new String[] { "河南省", "河北省", "山东省","山西省" };            //子视图显示文字            private String[][] city = new String[][] {                    { "郑州市", "开封市", "新乡市", "安阳市", "南阳市"},                    { "石家庄市", "邯郸市", "保定市", "廊坊市"},                    { "济南市", "青岛市", "日照市", "烟台市", "威海市" },                    { "太原市", "大同市", "晋城市", "吕梁市", "长治市" }            };                        //自己定义一个获得文字信息的方法            TextView getTextView() {                AbsListView.LayoutParams lp = new AbsListView.LayoutParams(                        ViewGroup.LayoutParams.MATCH_PARENT, 64);                TextView textView = new TextView(MainActivity.this);                textView.setLayoutParams(lp);                textView.setGravity(Gravity.CENTER_VERTICAL);                textView.setPadding(36, 0, 0, 0);                textView.setTextSize(20);                textView.setTextColor(Color.BLACK);                return textView;            }                        //重写ExpandableListAdapter中的各个方法            @Override            public int getGroupCount() {                return province.length;            }            @Override            public Object getGroup(int groupPosition) {                return province[groupPosition];            }            @Override            public long getGroupId(int groupPosition) {                return groupPosition;            }            @Override            public int getChildrenCount(int groupPosition) {                return city[groupPosition].length;            }            @Override            public Object getChild(int groupPosition, int childPosition) {                return city[groupPosition][childPosition];            }            @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) {                LinearLayout ll = new LinearLayout(MainActivity.this);                ll.setOrientation(0);                TextView textView = getTextView();                textView.setTextColor(Color.BLACK);                textView.setText(getGroup(groupPosition).toString());                ll.addView(textView);                return ll;            }            @Override            public View getChildView(int groupPosition, int childPosition,                    boolean isLastChild, View convertView, ViewGroup parent) {                LinearLayout ll = new LinearLayout(MainActivity.this);                ll.setOrientation(0);                TextView textView = getTextView();                textView.setText(getChild(groupPosition, childPosition).toString());                ll.addView(textView);                return ll;            }            @Override            public boolean isChildSelectable(int groupPosition,int childPosition) {                return true;            }        };                ExpandableListView expandableListView = (ExpandableListView) findViewById(R.id.province);        expandableListView.setAdapter(adapter);                //设置item点击的监听器        expandableListView.setOnChildClickListener(new OnChildClickListener() {            @Override            public boolean onChildClick(ExpandableListView parent, View v,                    int groupPosition, int childPosition, long id) {                Toast.makeText(                MainActivity.this,                        adapter.getChild(groupPosition, childPosition).toString(),                        Toast.LENGTH_SHORT).show();                return false;            }        });    }}

三、运行结果