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 viewprivate int[] grouplogo = new int[]{R.drawable.color,R.drawable.person,R.drawable.animal};//child viewprivate 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 intgetChildrenCount(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 intgetGroupCount(){            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：