初學者線程練習關於非同步和同步

package com.fish.thread;

 

publicclass Test22 {

publicstaticvoid main(String[] args) {

    Inc inc=new Inc(0);

    Dec dec=new Dec(1);

    for(
int i=0;i<2;i++){

        new Thread(inc).start();

        new Thread(dec).start();

    }

}

}

 class Inc
implements Runnable{

     int j=10;

     Object mutex;

     public Inc(Object mutex) {

        this.mutex = mutex;

    }

    @Override

    publicvoid run() {

        //
TODO Auto-generated method stub

         synchronized (mutex) {

           

   

         for(int i=10;i>0;i--){

             System.out.println(Thread.currentThread().getName()+"*******j="+j--);

         }

         

         }

    }

 }

 class Dec
implements Runnable{

     int j=10;

     Object mutex;

     

     public Dec(Object mutex) {

        this.mutex = mutex;

    }

 

    @Override

     publicvoid run() {

         //
TODO Auto-generated method stub

         synchronized (mutex) {

           

       

         for(int i=10;i>0;i--){

             System.out.println(Thread.currentThread().getName()+"&&&j="+j++);

         }

         }

         

     }

 }

 

Thread-0*******j=10

Thread-0*******j=9

Thread-0*******j=8

Thread-1&&&j=10

Thread-0*******j=7

Thread-1&&&j=11

Thread-0*******j=6

Thread-0*******j=5

Thread-0*******j=4

Thread-1&&&j=12

Thread-0*******j=3

Thread-1&&&j=13

Thread-0*******j=2

Thread-1&&&j=14

Thread-0*******j=1

Thread-1&&&j=15

Thread-1&&&j=16

Thread-2*******j=0

Thread-1&&&j=17

Thread-2*******j=-1

Thread-2*******j=-2

Thread-2*******j=-3

Thread-2*******j=-4

Thread-2*******j=-5

Thread-2*******j=-6

Thread-2*******j=-7

Thread-2*******j=-8

Thread-2*******j=-9

Thread-1&&&j=18

Thread-1&&&j=19

Thread-3&&&j=20

Thread-3&&&j=21

Thread-3&&&j=22

Thread-3&&&j=23

Thread-3&&&j=24

Thread-3&&&j=25

Thread-3&&&j=26

Thread-3&&&j=27

Thread-3&&&j=28

Thread-3&&&j=29

這個說明t0，t2是同步的，資源也是gx。這兩個為一組，另外兩個為另一組，兩組之間是非同步。

同步的標誌就是1一個執行，另一個必須等待。

用runnable的好處是可以實現資源資源共用。不是說thread不能是實現資源共用。只是runnable更好。