Detailed introduction and example code of java thread lock

java thread lock

Use the synchronized keyword in Java threads to achieve synchronization

synchronized can lock methods, lock classes, lock objects, and lock code blocks

Method lock

// 加在方法上面的同步锁是this
  public synchronized void print() {
    System.out.println("同步方法");
    try {
      Thread.sleep(3000);
    } catch (InterruptedException e) {
      e.printStackTrace();
    }
  }

Class lock

public synchronized void print(String msg) {
    // 类锁
    synchronized (MyThread.class) {
      System.out.println(msg);
      try {
        Thread.sleep(3000);
      } catch (InterruptedException e) {
        e.printStackTrace();
      }
    }
  }

Object lock

Take selling train tickets as an example

public class Window extends Thread {
 
  public Window(String name) {
    super(name);
  }
 
  static int tick = 100;
  static String obj = new String();
 
  @Override
  public void run() {
    // 开始卖票
    while (tick > 0) {
      // 同步代码块
      // 一把锁 钥匙
      // 所有的线程 必须在这里排队
      synchronized (obj) {
        if (tick > 0) {
          System.out.println(getName() + "卖出了第【" + tick + "】张票");// 失去了cpu资源
          tick--;
        }
      }
      try {
        Thread.sleep(100);
      } catch (InterruptedException e) {
        e.printStackTrace();
      }
    }
 
  }
}

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