Menu和AlertDialog对话框

  要在一个activity中实现菜单必须重写两个方法：
  1. onCreateOptionsMenu()用于创建菜单
  2. onOptionsItemSelected() 用于处理点击菜单选项事件
  实例代码：
 

package com.kevin.dialog;

import android.app.Activity;
import android.app.AlertDialog;
import android.content.DialogInterface;
import android.os.Bundle;
import android.view.Menu;
import android.view.MenuItem;

public class Main extends Activity {
	private static final int HELPGROUP = 0;
    /** Called when the activity is first created. */
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);
    }
    private void openOptionsDialog(){
    	AlertDialog.Builder builder = new AlertDialog.Builder(this);
    	// 设置标题
    	builder.setTitle(R.string.about);
    	// 设置对话框信息
    	builder.setMessage(R.string.message);
        // 添加确定按钮
    	builder.setPositiveButton(R.string.ok, new DialogInterface.OnClickListener() {			
    		// 点击确定单击事件处理
    		@Override
			public void onClick(DialogInterface dialog, int which) {				
				System.out.println("确定按钮被点击.");
			}
		});
    	 // 添加取消按钮
    	builder.setNegativeButton(R.string.cancel, new DialogInterface.OnClickListener() {
			
			@Override
			public void onClick(DialogInterface dialog, int which) {
				System.out.println("取消按钮被点击.");
			}
		});
    	// 显示对话框
    	builder.show();
    }
    // 要实现菜单必须实现以下两个函数(onCreateOptionsMenu和onOptionsItemSelected)
	// 创建菜单
    @Override
	public boolean onCreateOptionsMenu(Menu menu) {
		menu.add(HELPGROUP, 0, 0, R.string.about);
		menu.add(HELPGROUP, 1, 1, R.string.close);
		return super.onCreateOptionsMenu(menu);
	}
    // 选择item并相应
	@Override
	public boolean onOptionsItemSelected(MenuItem item) {		
		switch (item.getItemId()) {
		// 关于选项
		case 0:
			openOptionsDialog();
			break;
		// 关闭选项
		case 1:
			finish();
			break;
		default:
			break;
		}
		return super.onOptionsItemSelected(item);
	}
}