Java并发程序入门

     今天看了看Java并发程序，写一写入门程序，并设置了线程的优先级。

class Elem implements Runnable{
    public static int id = 0;
    private int cutDown = 5;
    private int priority;
    
    public void setPriority(int priority){
        this.priority = priority;
    }
    
    public int getPriority(){
        return this.priority;
    }
    public void run(){
        Thread.currentThread().setPriority(priority);
        int threadId = id++;
        while(cutDown-- > 0){
            double d = 1.2;
            while(d < 10000)
                d = d + (Math.E + Math.PI)/d;
            System.out.println("#" + threadId + "(" + cutDown + ")");
        }
    }
}
public class Basic {
    public static void main(String args[]){
        for(int i = 0; i < 10; i++){
            Elem e = new Elem();
            if(i == 0 )
                e.setPriority(Thread.MAX_PRIORITY);
            else
                e.setPriority(Thread.MIN_PRIORITY);
            Thread t = new Thread(e);
            t.start();
        }
    }
}

      由于机器很强悍，所以先开始并没看到并发的效果，感觉是按顺序执行的，所以在中间加了浮点数的运算来延迟时间。

      当然，main函数里面可以用Executors来管理线程。

import java.util.concurrent.*;
class Elem implements Runnable{
    public static int id = 0;
    private int cutDown = 5;
    private int priority;
    
    public void setPriority(int priority){
        this.priority = priority;
    }
    
    public int getPriority(){
        return this.priority;
    }
    public void run(){
        Thread.currentThread().setPriority(priority);
        int threadId = id++;
        while(cutDown-- > 0){
            double d = 1.2;
            while(d < 10000)
                d = d + (Math.E + Math.PI)/d;
            System.out.println("#" + threadId + "(" + cutDown + ")");
        }
    }
}
public class Basic {
    public static void main(String args[]){
//        for(int i = 0; i < 10; i++){
//            Elem e = new Elem();
//            if(i == 0 )
//                e.setPriority(Thread.MAX_PRIORITY);
//            else
//                e.setPriority(Thread.MIN_PRIORITY);
//            Thread t = new Thread(e);
//            t.start();
//        }
        ExecutorService exec = Executors.newCachedThreadPool();
        for(int i = 0; i < 10; i++){
            Elem e = new Elem();
            if(i == 0 )
                e.setPriority(Thread.MAX_PRIORITY);
            else
                e.setPriority(Thread.MIN_PRIORITY);
            exec.execute(e);
        }
        exec.shutdown();
    }
}