Dialog中添加多选按钮CheckBox

import android.app.Activity;
import android.app.AlertDialog;
import android.content.DialogInterface;
import android.content.DialogInterface.OnMultiChoiceClickListener;
import android.os.Bundle;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.ListView;

public class MainActivity extends Activity implements OnClickListener {
    private String[] province = new String[] { "上海", "北京", "湖南", "湖北", "海南" };
    private Button btnMultiChoice;
    private ListView lv;

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        btnMultiChoice = (Button) findViewById(R.id.btnMultiChoice);
        btnMultiChoice.setOnClickListener(this);
    }

    @Override
    public void onClick(View v) {
        showMultiChoiceItems();
    }

    private void showMultiChoiceItems() {
        AlertDialog builder = new AlertDialog.Builder(this)
                .setTitle("请选择你的省份：")
                .setMultiChoiceItems(province,
                        new boolean[] { false, false, false, false, false },
                        new OnMultiChoiceClickListener() {

                            @Override
                            public void onClick(DialogInterface dialog,
                                    int which, boolean isChecked) {
                                // TODO Auto-generated method stub
                            }
                        })
                .setPositiveButton("确定", new DialogInterface.OnClickListener() {

                    @Override
                    public void onClick(DialogInterface dialog, int which) {

                        String s = "您选择了：";
                        // 扫描所有的列表项，如果当前列表项被选中，将列表项的文本追加到s变量中。
                        for (int i = 0; i < province.length; i++) {
                            if (lv.getCheckedItemPositions().get(i)) {
                                s += i + ":" + lv.getAdapter().getItem(i) + " ";
                            }
                        }

                        // 用户至少选择了一个列表项
                        if (lv.getCheckedItemPositions().size() > 0) {
                            new AlertDialog.Builder(MainActivity.this)
                                    .setMessage(s).show();
                            System.out.println(lv.getCheckedItemPositions()
                                    .size());
                        }

                        // 用户未选择任何列表项
                        else if (lv.getCheckedItemPositions().size() <= 0) {
                            new AlertDialog.Builder(MainActivity.this)
                                    .setMessage("您未选择任何省份").show();
                        }
                    }
                }).setNegativeButton("取消", null).create();
        lv = builder.getListView();
        builder.show();
    }
}