java多线程之(synchronized)-优快云博客

本文链接：https://blog.youkuaiyun.com/u011747152/article/details/85158857

本文深入探讨了Java中synchronized关键字的使用及其特性，包括锁重入、异常处理和对象锁的概念。通过实例对比静态与非静态方法的锁行为，展示了如何避免死锁和正确实现线程间的同步。

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public class MyThread {
	private static int i=5;
	public static synchronized void print(String a) {
		if(a.equals("a")) {
			i--;
			System.out.println("a "+i);
		}else {
			i=i-2;
			System.out.println("b "+i);
		}
		System.out.println("last "+i);
	}
	
	public static void main(String[] args) {
		final MyThread thread=new MyThread();
		final MyThread thread1=new MyThread();
		new Thread(new Runnable() {
			
			@Override
			public void run() {
				// TODO Auto-generated method stub
				thread.print("a");
			}
		}).start();
		new Thread(new Runnable() {
			
			@Override
			public void run() {
				// TODO Auto-generated method stub
				thread1.print("b");
			}
		}).start();


	}


}

a 4
last 4
b 2
last 2

在变量和方法上加static ,在该类的所有对象是具有相同的引用的

public class MyThread {
	private  int i=5;
	public  synchronized void print(String a) {
		if(a.equals("a")) {
			i--;
			System.out.println("a "+i);
		}else {
			i=i-2;
			System.out.println("b "+i);
		}
		System.out.println("last "+i);
	}
	
	public static void main(String[] args) {
		final MyThread thread=new MyThread();
		final MyThread thread1=new MyThread();
		new Thread(new Runnable() {
			
			@Override
			public void run() {
				// TODO Auto-generated method stub
				thread.print("a");
			}
		}).start();
		new Thread(new Runnable() {
			
			@Override
			public void run() {
				// TODO Auto-generated method stub
				thread1.print("b");
			}
		}).start();


	}


}