[Android]BaseExpandableListAdapter實作可折疊清單

使用BaseExpandableListAdapter 以實作的可折疊的所謂清單，例如QQ朋友們在分組功能。

基于BaseExpandableListAdapter擴大ExpandableList說明，今天，有兩個主要的網上流行：第一種方法是BaseExpandableListAdapter傳入兩個數組，第一個是表示Group（檔案夾頭）資訊的一維數組，第二個是表示Child（檔案夾子項）的二維數組數組；另外一種是建構兩個類，一個是表示檔案夾資訊的GroupInfo類。還有一個是表示子項資訊的ChildInfo類，然後傳入BaseExpandableListAdapter。通過對照發現，第一種方法因為數組是固定的。而實際項目中往往須要動态變化的檔案夾和子項。是以用處不大。另外一種方法檔案太多，實作複雜。這裡提供一種方法，傳遞兩個個動态的二維數組來實作檔案夾結構。

package com.example.test;

import java.util.ArrayList;

import android.os.Bundle;
import android.app.Activity;
import android.graphics.Color;
import android.graphics.drawable.ColorDrawable;
import android.view.Gravity;
import android.view.Menu;
import android.view.View;
import android.view.ViewGroup;
import android.widget.BaseExpandableListAdapter;
import android.widget.ExpandableListAdapter;
import android.widget.ExpandableListView;
import android.widget.ImageView;
import android.widget.LinearLayout;
import android.widget.TextView;
import android.view.View.OnClickListener;

public class MainActivity extends Activity {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        //Group資料
        ArrayList<String> groupList = new ArrayList<String>();
        groupList.add("我的好友");
        groupList.add("我的親人");
        groupList.add("我的同學");
        //Child資料
        ArrayList<String> itemList1 = new ArrayList<String>();
        itemList1.add("小米");
        itemList1.add("小李");
        ArrayList<String> itemList2 = new ArrayList<String>();
        itemList2.add("小麗");
        itemList2.add("小小");
        itemList2.add("小可");
        ArrayList<String> itemList3 = new ArrayList<String>();
        itemList3.add("小南");
        itemList3.add("小飛");
        itemList3.add("小丁");
        itemList3.add("小美");
        ArrayList<ArrayList<String>> childList = new ArrayList<ArrayList<String>>();
        childList.add(itemList1);
        childList.add(itemList2);
        childList.add(itemList3);
        //可折疊List
        ExpandableListView list = new ExpandableListView(this);
        ExpandableListAdapter mAdapter = new MyExpandableListAdapter(groupList, childList);
        list.setAdapter(mAdapter);

        list.setCacheColorHint(0x00000000);
        list.setSelector(new ColorDrawable(Color.TRANSPARENT));
        list.setGroupIndicator(null);
        for (int i = 0; i < mAdapter.getGroupCount(); i++) {
            list.expandGroup(i);
        }
        setContentView(list);
    }
    //Adapter
    private class MyExpandableListAdapter extends BaseExpandableListAdapter {
        private ArrayList<String> groupList;
        private ArrayList<ArrayList<String>> childList;

        MyExpandableListAdapter(ArrayList<String> groupList, ArrayList<ArrayList<String>> childList) {
            this.groupList = groupList;
            this.childList = childList;
        }

        public Object getChild(int groupPosition, int childPosition) {
            return childList.get(groupPosition).get(childPosition);
        }

        private int selectedGroupPosition = -1;
        private int selectedChildPosition = -1;

        public void setSelectedPosition(int selectedGroupPosition, int selectedChildPosition) {
            this.selectedGroupPosition = selectedGroupPosition;
            this.selectedChildPosition = selectedChildPosition;
        }

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

        public int getChildrenCount(int groupPosition) {
            return childList.get(groupPosition).size();
        }

        public View getChildView(final int groupPosition, final int childPosition, boolean isLastChild, View convertView, ViewGroup parent) {
            TextView textView = null;
            if (convertView == null) {
                textView = new TextView(MainActivity.this);
                textView.setPadding(32, 10, 0, 10);
                convertView = textView;
            } else {
                textView = (TextView) convertView;
            }

            textView.setText(getChild(groupPosition, childPosition).toString());

            if (groupPosition == selectedGroupPosition) {
                if (childPosition == selectedChildPosition) {
                    textView.setBackgroundColor(0xffb6ddee);
                } else {
                    textView.setBackgroundColor(Color.TRANSPARENT);
                }
            }

            textView.setOnClickListener(new OnClickListener() {
                public void onClick(View v) {
                    setSelectedPosition(groupPosition, childPosition);
                    notifyDataSetChanged();
                }
            });
            return textView;
        }

        public Object getGroup(int groupPosition) {
            return groupList.get(groupPosition);
        }

        public int getGroupCount() {
            return groupList.size();
        }

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

        public View getGroupView(int groupPosition, boolean isExpanded, View convertView, ViewGroup parent) {
            LinearLayout cotain = new LinearLayout(MainActivity.this);
            cotain.setPadding(0, 10, 0, 10);
            cotain.setGravity(Gravity.CENTER_VERTICAL);

            ImageView imgIndicator = new ImageView(MainActivity.this);
            TextView textView = new TextView(MainActivity.this);
            textView.setText(getGroup(groupPosition).toString());
            textView.setPadding(5, 0, 0, 0);

            if (isExpanded) {
                imgIndicator.setBackgroundResource(R.drawable.bg_arrow_up);
            } else {
                imgIndicator.setBackgroundResource(R.drawable.bg_arrow_down);
            }
            cotain.addView(imgIndicator);
            cotain.addView(textView);
            return cotain;
        }

        public boolean hasStableIds() {
            return true;
        }

        public boolean isChildSelectable(int groupPosition, int childPosition) {
            return true;
        }
    }

    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        getMenuInflater().inflate(R.menu.main, menu);
        return true;
    }
}
           

groupList 用于組名（類似QQ好友、同學、朋友），

childList 每個元素是一組子資料的（類似QQ同學約翰·史密斯，收集李四)