Java中同步

 

解决资源共享的同步操作，有两种方法：一是同步代码块，二是同步方法。

在需要同步的代码块加上synchronized关键字，

同步代码块时必须指定一个需要同步的对象，但一般都是将当前对象（this）设置成同步对象。

class Thread8 implements Runnable{
	private int ticket = 5;
	public void run(){
		for(int i=0; i<100; i++){
			synchronized (this) {
				if(ticket>0){
					try {
						Thread.sleep(300);
					} catch (Exception e) {
						// TODO: handle exception
						e.printStackTrace();
					}
					System.out.println("买票： ticket = "+ticket--);
				}
			}
			
		}
	}
}

public class SyncDemo {

	public static void main(String[] args) {
		// TODO Auto-generated method stub
		Thread8 tt = new Thread8();
		Thread t1 = new Thread(tt);
		Thread t2 = new Thread(tt);
		Thread t3 = new Thread(tt);
		
		t1.start();
		t2.start();
		t3.start();
	}

}

　　同步方法使用synchronized关键字将一个方法声明成同步方法。格式如下：

class Thread9 implements Runnable{
	private int ticket = 5;
	@Override
	public void run() {
		// TODO Auto-generated method stub
		for(int i = 0; i<100; i++){
			this.sale();
		}
	}
	
	public synchronized void sale(){
		if (ticket>0) {
			try {
				Thread.sleep(300);
			} catch (Exception e) {
				// TODO: handle exception
				e.printStackTrace();
			}
			System.out.println("买票： ticket = "+ ticket--);
		}
	}
}


public class SyncDemo02 {

	public static void main(String[] args) {
		// TODO Auto-generated method stub
		Thread9 tt = new Thread9();
		Thread t1 = new Thread(tt);
		Thread t2 = new Thread(tt);
		Thread t3 = new Thread(tt);
		
		t1.start();
		t2.start();
		t3.start();		
	}
}