用Handler写简单的计时功能

package com.example.testtt;

import android.app.Activity;
import android.os.Bundle;
import android.os.Handler;
import android.widget.Toast;

public class MainActivity extends Activity {
	//在主线程里面定义一个Handler
	private Handler handler = new Handler();
	private boolean isOut = true;
	
	@Override
	protected void onCreate(Bundle savedInstanceState) {
		super.onCreate(savedInstanceState);
		setContentView(R.layout.activity_main);
		
		//3秒之后运行线程
		handler.postDelayed(new MyRunnable(), 3000);
	}
	
	class MyRunnable implements Runnable {
		@Override
		public void run() {
			Toast.makeText(MainActivity.this, "3秒过去了。。。", Toast.LENGTH_SHORT).show();
			//循环
			if(isOut) {
				handler.postDelayed(new MyRunnable(), 3000);
			}
		}
	}

	@Override
	protected void onPause() {
		//程序推出以后handler.postDelayed(new MyRunnable(), 3000);仍然会运行
		//所以一定要记住处理
		isOut = false;
		super.onPause();
	}
	
	
}