Android应用开发之多选删除之二

MultiSelectDeleteActivity.java

[java]
package cn.lynn.multisel;

import java.util.HashMap;
import java.util.HashSet;

import android.app.Activity;
import android.app.AlertDialog;
import android.app.ProgressDialog;
import android.content.ContentUris;
import android.content.Context;
import android.content.DialogInte易做图ce;
import android.database.Cursor;
import android.net.Uri;
import android.os.AsyncTask;
import android.os.Bundle;
import android.provider.ContactsContract.Contacts;
import android.util.Log;
import android.view.LayoutInflater;
import android.view.View;
import android.view.View.OnClickListener;
import android.view.ViewGroup;
import android.widget.AdapterView;
import android.widget.AdapterView.OnItemClickListener;
import android.widget.BaseAdapter;
import android.widget.Button;
import android.widget.CheckBox;
import android.widget.ListView;
import android.widget.TextView;

public class MultiSelectDeleteActivity extends Activity implements OnClickListener, OnItemClickListener {

    private static final String TAG = "MultiSelectDeleteActivity";
    private ListView delList;
    private Button delBtn;
    private Button canBtn;
    private CheckBox selAllChk;
    private Cursor cursor;
    private DeleteListAdapter delListAdapter;
    // 期望查询的联系人字段
    private static final String[] PROJECTION = new String[] {Contacts._ID, Contacts.DISPLAY_NAME};
    private static final int CONTACTS_ID_INDEX = 0;
    private static final int DISPLAY_NAME_INDEX = 1;

    // 用于保存记录是否被选中的状态，这里定义为静态变量是为了防止Home键切换之后普通成员变量无法保存切换之前的数据
    private static HashMap<Integer, Boolean> statusMap;

    /**
     * 用于删除的联系人记录的封装类
     */
    private final class ViewHolder {
        TextView nameTxt;
        CheckBox selectChk;
    }

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);

        statusMap = new HashMap<Integer, Boolean>();

        delList = (ListView) findViewById(R.id.del_list);
        delBtn = (Button) findViewById(R.id.del_btn);
        canBtn = (Button) findViewById(R.id.can_btn);
        selAllChk = (CheckBox) findViewById(R.id.select_all).findViewById(R.id.select_all_chk);

        delList.setOnItemClickListener(this);
        delBtn.setOnClickListener(this);
        canBtn.setOnClickListener(this);
        selAllChk.setOnClickListener(new SelectAllClickListener());
    }

    @Override
    protected void onDestroy() {
        super.onDestroy();
        statusMap.clear();
        // 静态变量，提示和加快GC回收它，否则有很大可能要等到VM Full gc时才能回收
        statusMap = null;
    }

    @Override
    public void onResume() {
        super.onResume();
        refreshData();
    }

    /**
     * 查询联系人数据库记录
     */
    private void refreshData() {
        selAllChk.setEnabled(false);
        cursor = getContentResolver().query(Contacts.CONTENT_URI, PROJECTION, null, null, null);
        if(cursor.getCount() > 0) {
            selAllChk.setEnabled(true);
        }
        Log.i(TAG, "cursor= " + cursor);
        delListAdapter = new DeleteListAdapter(this, cursor);
        delList.setAdapter(delListAdapter);
    }

    /**
     * 单独为全选CheckBox设置点击事件的易做图，因为它的布局是从当前Activity的子布局文件R.id.select_all中加载而来，
     * 这样做的好处是防止多个按钮都在Activity布局层次上监听同类点击事件时出现“屏蔽”现象
     */
    private class SelectAllClickListener implements OnClickListener {
        @Override
        public void onClick(View v) {
            if(selAllChk.isChecked()) {
                for (int i = 0; i < delListAdapter.getCount(); i++) {
                    statusMap.put(i, true);
                    delListAdapter.cursor.moveToPosition(i);
                    delListAdapter.idSet.add(delListAdapter.cursor.getInt(CONTACTS_ID_INDEX) + "");
                }
                delBtn.setEnabled(true);
            } else {
                for (int i = 0;

补充：移动开发 , Android ,