java多线程同步方式

1 同步代码块 自定义锁

class Thread33 implements Runnable{
	int a = 100;
	Object obj = new Object();
	@Override
	public void run() {
	    while(a > 0){
	    		try {
					Thread.sleep(100);
				} catch (InterruptedException e) {
					e.printStackTrace();
				}
	    		synchronized (obj) {
	    			if(a > 0){
	    				Thread thread = Thread.currentThread();
		    			System.out.println(thread.getName() +" "+ a);
		    			a--;
	    			}
	    		}
	    }	
	}
}
public class Thread3 {
	public static void main(String[] args) {
		Thread33 thread3 = new Thread33();
		Thread thread1 = new Thread(thread3);
		thread1.start();
		Thread thread2 = new Thread(thread3);
		thread2.start();
		Thread thread4 = new Thread(thread3);
		thread4.start();
	}
}

2 同步函数 同步函数使用this锁

 class Thread44 implements Runnable{
    	int a = 100;
    	Object obj = new Object();
    	@Override
    	public void run() {
    	    while(a > 0){
    	    		try {
    					Thread.sleep(100);
    				} catch (InterruptedException e) {
    					e.printStackTrace();
    				}
    	    		this.jian(a);
    	    }
    	}
    	public synchronized void jian(int a){
    		if(a > 0){
    			a--;
    		}
    	}
    }
    public class Thread4 {
    	public static void main(String[] args) {
    		Thread33 thread3 = new Thread33();
    		Thread thread1 = new Thread(thread3);
    		thread1.start();
    		Thread thread2 = new Thread(thread3);
    		thread2.start();
    		Thread thread4 = new Thread(thread3);
    		thread4.start();
    	}
    }

3 静态同步函数 方法上加上static关键字 使用synchronized 关键字修饰 或者使用类.class文件