显示对话框窗体

1、创建Dialog1项目，在activity_main.xml文件里加入一个Button：

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:paddingBottom="@dimen/activity_vertical_margin"
    android:paddingLeft="@dimen/activity_horizontal_margin"
    android:paddingRight="@dimen/activity_horizontal_margin"
    android:paddingTop="@dimen/activity_vertical_margin"
    tools:context=".MainActivity" >

    <Button
        android:id="@+id/btn_dialog"
        android:layout_width="fill_parent"
        android:layout_height="wrap_content"
        android:onClick="onClick"
        android:text="Click to display a dialog" />

</RelativeLayout>

package com.example.dialog;

import android.os.Bundle;
import android.app.Activity;
import android.app.AlertDialog;
import android.app.Dialog;
import android.content.DialogInterface;
import android.view.Menu;
import android.view.View;
import android.widget.Toast;

public class MainActivity extends Activity {
	CharSequence[] items = { "Google", "Apple", "Microsoft" };
	boolean[] itemsChecked = new boolean[items.length];

	@Override
	protected void onCreate(Bundle savedInstanceState) {
		super.onCreate(savedInstanceState);
		setContentView(R.layout.activity_main);
	}

	@SuppressWarnings("deprecation")
	public void onClick(View v) {
		showDialog(0);//点击button时，显示对话框，此方法接受一个整型參数，用来标识要显示的特定对话框（这里仅仅创建了标识为0的对话框）。
	}

	@Override
	@Deprecated
	//onCreateDialog()方法是一个用于创建由活动管理的对话框的回调方法。当调用showDialog()时，将调用此回调方法。
	protected Dialog onCreateDialog(int id) {
		// TODO Auto-generated method stub
		switch (id) {
		case 0://要创建一个对话框。须要使用AlertDialog类的Builder构造函数来设置不同的属性，如图标、标题、button及复选框等。
			return new AlertDialog.Builder(this)//调用AlertDialog对象的Builder构造函数。
					.setIcon(R.drawable.ic_launcher)
					.setTitle("This is a dialog with some simple text...")
					.setPositiveButton("OK",//设置OKbutton
							new DialogInterface.OnClickListener() {//设置点击事件

								@Override
								public void onClick(DialogInterface dialog,
										int which) {
									// TODO Auto-generated method stub
									Toast.makeText(getBaseContext(),
											"OK clicked!", Toast.LENGTH_SHORT)
											.show();
								}
							})
					.setNegativeButton("Cancel",//设置Cancelbutton
							new DialogInterface.OnClickListener() {//设置点击事件

								@Override
								public void onClick(DialogInterface dialog,
										int which) {
									// TODO Auto-generated method stub
									Toast.makeText(getBaseContext(),
											"Cancel clicked!",
											Toast.LENGTH_SHORT).show();
								}
							})
					.setMultiChoiceItems(items, itemsChecked,//设置复选框
							new DialogInterface.OnMultiChoiceClickListener() {//设置点击事件

								@Override
								public void onClick(DialogInterface dialog,
										int which, boolean isChecked) {
									// TODO Auto-generated method stub
									Toast.makeText(
											getBaseContext(),
											items[which]//通过传入检验是否点击的參数isChecked来选择返回的消息。

													+ (isChecked ? " checked!"
															: " unchecked!"),
											Toast.LENGTH_SHORT).show();
								}
							}).create();
		}
		return null;
	}

	@Override
	public boolean onCreateOptionsMenu(Menu menu) {
		// Inflate the menu; this adds items to the action bar if it is present.
		getMenuInflater().infla