多线程与并发

//通过继承Thread类来创建线程类
public class FirstThread extends Thread
{	private int i ;
	//重写run方法，run方法的方法体就是线程执行体
	public void run()	{
		for ( ; i < 100 ; i++ ){System.out.println(getName() +  " " + i);}}	
    public static void main(String[] args)    {
        for (int i = 0; i < 100;  i++) {
	//调用Thread的currentThread方法获取当前线程
	System.out.println(Thread.currentThread().getName() +  " " + i);
	if (i == 20){	               
		new FirstThread().start();
		new FirstThread().start();
		}        }    }}

//通过实现Runnable接口来创建线程类
public class MyRunnable implements Runnable
{
	private int i ;
	//run方法同样是线程执行体
	public void run(){
	   for ( ; i < 100 ; i++ ){
	       //当线程类实现Runnable接口时，
	       //如果想获取当前线程，只能用Thread.currentThread()方法。
	       System.out.println(Thread.currentThread().getName() + "  " + i);
	    }
	}
}
Runnable接口与Thread构造函数
//通过new Thread(target , name)方法创建新线程
public class Client
{
   public static void main(String[] args)     {
	for (int i = 0; i < 100;  i++){
	   System.out.println(Thread.currentThread().getName() + "  " + i);
	   if (i == 20){
	       MyRunnable task = new MyRunnable ();
	       //通过new Thread(target , name)方法创建新线程
	       new Thread(task , "新线程1").start();
	       new Thread(task , "新线程2").start();
	   }   }}

// 使用Callable和Future创建线程类

//接口 Callable<Integer>???
import java.util.concurrent.Callable;
public class MyCallable implements Callable<Integer>{
	public Integer call() throws Exception {
	    int i = 0;
	    for(;i<100;i++){
	       System.out.println(Thread.currentThread().getName()+"的循环变量I="+i);
	    }
	    //call方法可以有返还值，使用泛型来定义返回值
	   return i;
	}}
public static void main(String[] args) {
	MyCallable rt = new MyCallable();
	FutureTask<Integer> task = new FutureTask<Integer>(rt);
	for(int i=0;i<100;i++){
		System.out.println(Thread.currentThread().getName()+"的循环变量I="+i);
		if (i==20){
		     new Thread(task,"有返回值的线程").start();
		}}
	try{
	         System.out.println("子线程的返回值="+task.get());
	}catch (Exception ex){	ex.printStackTrace();}
}