Android可伸缩列表ExpandableListView

<?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>

package com.example.yanlei.my;

import android.app.Activity;
import android.graphics.Color;
import android.os.Bundle;
import android.support.v7.app.AppCompatActivity;
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 AppCompatActivity {

    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;
            }
        });
    }
}