Android UI ExpandableListActivity与ExpandableListActivity

介绍：

ExpandableListView是ListView的子类，它把应用中的列表项分为几组，每组里面又可以包含多个列表项。而所显示的列表项应该由ExpandableListAdapter提供。

ExpandableListAdapter常用的使用方法是通过扩展BaseExpandablelistAdapter来实现。
关键是实现如下四个方法：
（1）getGroupCount():返回包含的组列表项的数量；
（2）getGroupView():返回View对象将其作为组列表项；
（3）getChildrenCount():返回特定组所包含的子列表项的数量；
（4）getChildView():返回的View对象将作为特定组的特定位置的子列表项。

程序源码：

package com.example.expandablelistviewui;

import android.os.Bundle;
import android.app.Activity;
import android.graphics.Color;
import android.view.Gravity;
import android.view.Menu;
import android.view.View;
import android.view.ViewGroup;
import android.view.ViewGroup.LayoutParams;
import android.widget.AbsListView;
import android.widget.AdapterView;
import android.widget.BaseExpandableListAdapter;
import android.widget.ExpandableListAdapter;
import android.widget.ExpandableListView;
import android.widget.ImageView;
import android.widget.ImageView.ScaleType;
import android.widget.LinearLayout;
import android.widget.TextView;

public class MainActivity extends Activity {
	//
	private String []creatureTypes = new String[]{"Color","People","Animal"};
	private String [][]creatures = new String[][]{
			{"yellow","purple","red"},
			{"girl","libai","qingzhao","nongyu"},
			{"tiger"}
	};
	//group view
	private int[] grouplogo = new int[]{R.drawable.color,R.drawable.person,R.drawable.animal};
	//child view
	private int[][] generallogos = new int[][]{
			{R.drawable.color1,R.drawable.color2,R.drawable.color3},
			{R.drawable.person1,R.drawable.person2,R.drawable.person3,R.drawable.person5},
			{R.drawable.animal1}};
	//
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        //key  construct myself adapter
        ExpandableListAdapter adapter = new BaseExpandableListAdapter(){
        	@Override
        	public  Object getChild(int groupPosition, int childPosition){
        		return creatures[groupPosition][childPosition];
        	}
        	@Override
        	public long getChildId(int groupPosition, int childPosition){
        		return childPosition;
        	}
        	@Override
        	public int	getChildrenCount(int groupPosition){
        		return creatures[groupPosition].length;
        	}
        	
        	//****self define a method to display text content [***Set TextView UI] 
            private TextView getTextView() {
                AbsListView.LayoutParams lp = new AbsListView.LayoutParams(
                        ViewGroup.LayoutParams.FILL_PARENT, 64);
                TextView textView = new TextView(MainActivity.this);
                textView.setLayoutParams(lp);
                textView.setGravity(Gravity.CENTER_VERTICAL);
                textView.setPadding(50, 0, 0, 0);//左边距 50  【远离图标】
                textView.setTextSize(20);
                textView.setTextColor(Color.BLACK);
                return textView;
            }
        	
            ////决定每一个子选项的外观  调用前面定义的getTextView 和getChild methods
            @Override
            public View getChildView(int groupPosition, int childPosition, boolean isLastChild, View convertView, ViewGroup parent){
            	//add picture  ---addView
            	LinearLayout childLayout = new LinearLayout(MainActivity.this);
            	childLayout.setOrientation(0);
            	
            	ImageView childimage = new ImageView(MainActivity.this);
            	childimage.setPadding(30, 0, 0, 0);
            	//adjust size  1403
            	/*childimage.setLayoutParams(new LayoutParams(LayoutParams.FILL_PARENT,
            			LayoutParams.FILL_PARENT));*/
            	childimage.setLayoutParams(new LayoutParams(100,100));
            	
            	//childimage.setScaleType(ScaleType.FIT_CENTER);
            	
            	//
            	childimage.setImageResource(generallogos[groupPosition][childPosition]);
            	childLayout.addView(childimage);
            	
            	//add text  ---addView
  
            	TextView textView = this.getTextView();
            	textView.setText(this.getChild(groupPosition, childPosition).toString());
            	childLayout.addView(textView);
            	
            	return childLayout;
            	
            }
            
            //begin deal with group info
            
            
            @Override
            public Object getGroup(int groupPosition){
            	return creatureTypes[groupPosition];
            }
            @Override
            public int	getGroupCount(){
            	return creatureTypes.length;
            }
            @Override
            public long getGroupId(int groupPosition){
            	return groupPosition;
            }
            
            @Override
            //决定每个组选项的外观  
            public View getGroupView(int groupPosition, boolean isExpanded, View convertView, ViewGroup parent){
            	 LinearLayout ll = new LinearLayout(MainActivity.this);
                 ll.setOrientation(0);//0. set orientation
                 
                 ImageView logo = new ImageView(MainActivity.this);
                 
                 //1403
               /*
                 logo.setLayoutParams(new LayoutParams(LayoutParams.FILL_PARENT,
             			LayoutParams.FILL_PARENT));
             			*/
                 logo.setLayoutParams(new LayoutParams(150,150));
                 logo.setPadding(20, 0, 0, 0);//left top right bottom 边距
                // logo.setScaleType(ScaleType.FIT_XY);
                 
                 logo.setImageResource(grouplogo[groupPosition]);
                 ll.addView(logo);//1. add group image  (IMageView)
                 
                 TextView textView = getTextView();
                 textView.setTextColor(Color.BLACK);
                 
                 textView.setText(getGroup(groupPosition).toString());
                 ll.addView(textView);//2. add group name  (textView)

                 return ll;
            }
            
            @Override
            public  boolean	 isChildSelectable(int groupPosition, int childPosition){
            	return true;
            }
            
            @Override
            public boolean	 hasStableIds(){
            	return true;
            }
        };
        
        //
        ExpandableListView lstview = (ExpandableListView)findViewById(R.id.list);
        lstview.setAdapter(adapter);
        //set clickEvent  1403
        
        
    }


    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        // Inflate the menu; this adds items to the action bar if it is present.
        getMenuInflater().inflate(R.menu.main, menu);
        return true;
    }
    
}

ExpandableListActivity与ExpandableListActivity的用法基本相似，只要为该Activity传入一个ExpanableListAdapter对象即可，接下来的ExpandableListActivity将会生成一个显示可展开列表的窗口。

对应的代码修改片段（黑色为修改前，红色为修改后）：

(1)

//public class MainActivity extends Activity {
public class MainActivity extends ExpandableListActivity {

(2)

 setContentView(R.layout.activity_main);

//  setContentView(R.layout.activity_main);

(3)

ExpandableListView lstview = (ExpandableListView)findViewById(R.id.list);

lstview.setAdapter(adapter);

/*

 ExpandableListView lstview = (ExpandableListView)findViewById(R.id.list);

 lstview.setAdapter(adapter);*/

setListAdapter(adapter);//设置该窗口显示列表

运行结果：