package 经典;public class 四个线程 {        private int j=10;    /**     * @param args     */    public static void main(String[] args) {        // TODO Auto-generated method stub                四个线程 mainClass=new 四个线程();                for(int i=2; i>0; i--)        {            Thread thread=new Thread(mainClass.new IncThread());            thread.start();            thread=new Thread(mainClass.new DecThread());            thread.start();        }    }        private synchronized void inc(){        j++;        System.out.println(Thread.currentThread().getName()+", j="+j);    }        private synchronized void dec(){        j--;        System.out.println(Thread.currentThread().getName()+", j="+j);    }        class IncThread implements Runnable{        @Override        public void run() {            // TODO Auto-generated method stub            for(int i=20; i>0 ;i--)                inc();        }            }        class DecThread implements Runnable{        @Override        public void run() {            // TODO Auto-generated method stub            for(int i=20; i>0 ;i--)                dec();        }    }}