安卓开发之简单计时器

功能：Menu包括 计时、停止、清零

          长按计时器控件 弹出上下文菜单  包括开始计时、终止计时、清零

重点：长按计时器弹出上下文菜单。 

//长按计时器时，出现上下文菜单   
        this.registerForContextMenu(timer);

 

//创建上下文菜单   
    @Override  
    public void onCreateContextMenu(ContextMenu menu, View v,  
            ContextMenuInfo menuInfo)  
    {  
        super.onCreateContextMenu(menu, v, menuInfo);  
        // ContextMenu的Item不支持Icon，所以不用再资源文件中，为它们设定图标   
        if (v.getId() == R.id.chronometer)  
        {  
            //加载xml菜单布局文件   
            this.getMenuInflater().inflate(R.menu.main, menu);  
            // 设定头部图标   
            menu.setHeaderIcon(R.drawable.ic_launcher);   
            // 设定头部标题   
            menu.setHeaderTitle(" 计时器控制选项 ");  
        }  
    }  
    //选择菜单项后的响应   
    @Override  
    public boolean onContextItemSelected(MenuItem item)  
    {  
        switch (item.getItemId())  
        {  
        case R.id.timer_start:  
            // 将计时器清零   
            timer.setBase(SystemClock.elapsedRealtime());   
            //开始计时   
            timer.start();  
           return true;
        case R.id.timer_stop:  
            //停止计时   
            timer.stop();  
            return true;
        case R.id.timer_reset:  
            //将计时器清零   
            timer.setBase(SystemClock.elapsedRealtime());   
            return true; 
        } 
        return false;
        //return super.onContextItemSelected(item);  
    }  

 

MainActivuty.java

package com.example.timer1;

import android.os.Bundle;
import android.os.SystemClock;
import android.app.Activity;
import android.view.ContextMenu;
import android.view.ContextMenu.ContextMenuInfo;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import android.widget.Chronometer;

public class MainActivity extends Activity {

    private Chronometer timer;
    
    final static int menu_start = Menu.FIRST;
	final static int menu_stop = Menu.FIRST+1;
	final static int menu_setting = Menu.FIRST+2;

	@Override
	protected void onCreate(Bundle savedInstanceState) {
		super.onCreate(savedInstanceState);
		setContentView(R.layout.activity_main);
		
		// 获得计时器对象   
        timer = (Chronometer)this.findViewById(R.id.chronometer);  
        //长按计时器时，出现上下文菜单   
        this.registerForContextMenu(timer);  

	}
	
	//创建上下文菜单   
    @Override  
    public void onCreateContextMenu(ContextMenu menu, View v,  
            ContextMenuInfo menuInfo)  
    {  
        super.onCreateContextMenu(menu, v, menuInfo);  
        // ContextMenu的Item不支持Icon，所以不用再资源文件中，为它们设定图标   
        if (v.getId() == R.id.chronometer)  
        {  
            //加载xml菜单布局文件   
            this.getMenuInflater().inflate(R.menu.main, menu);  
            // 设定头部图标   
            menu.setHeaderIcon(R.drawable.ic_launcher);   
            // 设定头部标题   
            menu.setHeaderTitle(" 计时器控制选项 ");  
        }  
    }  
    //选择菜单项后的响应   
    @Override  
    public boolean onContextItemSelected(MenuItem item)  
    {  
        switch (item.getItemId())  
        {  
        case R.id.timer_start:  
            // 将计时器清零   
            timer.setBase(SystemClock.elapsedRealtime());   
            //开始计时   
            timer.start();  
           return true;
        case R.id.timer_stop:  
            //停止计时   
            timer.stop();  
            return true;
        case R.id.timer_reset:  
            //将计时器清零   
            timer.setBase(SystemClock.elapsedRealtime());   
            return true; 
        } 
        return false;
        //return super.onContextItemSelected(item);  
    }  
	
	public boolean onCreateOptionsMenu(Menu menu) {
		// Inflate the menu; this adds items to the action bar if it is present.
		//getMenuInflater().inflate(R.menu.main, menu);
		
		menu.add(0,menu_start,0,"计时");
		menu.add(0,menu_stop,1,"停止");
		menu.add(0,menu_setting,2,"清零");
		return true;
	}
	
	public boolean onOptionsItemSelected(MenuItem item) {
		// TODO Auto-generated method stub
	//	return super.onOptionsItemSelected(item);
	
		switch(item.getItemId())
		{
		case menu_start:
			 // 将计时器清零   
            timer.setBase(SystemClock.elapsedRealtime());   
            //开始计时   
            timer.start();  			
			return true;
		case menu_stop:
			//停止计时   
            timer.stop();  			
			return true;
		case menu_setting:
			 timer.setBase(SystemClock.elapsedRealtime());   
	         return true;
		
		}
		return false;
		
		
	}


}

activity_main.xml

main.xml