實作4個線程，其中2個每次加1，另外2個每次減1

/**寫四個線程 兩個線程加1兩個線程減1
 *1線程的同步 synchronized
 *2操作同一個變量 内部類
 */
public class ThreadMain {

	int j=1;
	public synchronized void inc()
	{
		j++;
		System.out.println(Thread.currentThread().getName()+"inc:"+j);
	}
	public synchronized void dec()
	{
		j--;
		System.out.println(Thread.currentThread().getName()+"dec"+j);
	}
     class T1 implements Runnable{

		@Override
		public void run() {
			// TODO Auto-generated method stub
			while(true)
			{
			inc();
			try {
				Thread.sleep((int) Math.random() * 10);
			} catch (InterruptedException e) {
				e.printStackTrace();
			}
			}
		}
    	 
     }
     class T2 implements Runnable{

		@Override
		public void run() {
			// TODO Auto-generated method stub
			while(true)
			{
			dec();
			try {
				Thread.sleep((int) Math.random() * 10);
			} catch (InterruptedException e) {
				e.printStackTrace();
			}
			}
		}
    	 
     }
	/**
	 * @param args
	 */
	public static void main(String[] args) {
		// TODO Auto-generated method stub
         ThreadMain t=new ThreadMain();
        T1 t1=t.new T1();
        T2 t2=t.new T2();
        
        	Thread thread1=new Thread(t1,"加線程1");
        	thread1.start();
        	Thread thread2=new Thread(t1,"加線程2");
        	thread2.start();
        	Thread thread3=new Thread(t2,"減線程1");
        	thread3.start();
        	Thread thread4=new Thread(t2,"減線程2");
        	thread4.start();
       
	}
	

}