同步锁

public class Ticket implements Runnable {               //实现Runnable接口 创建多线程 引发 线程安全问题 
    
    private int tickets=100;
    
    public void run() {
        while(true) {                                          
            try {
                if(tickets>0) {    
                    
                Thread.sleep(10);                                //使线程休眠
            
                String name=Thread.currentThread().getName();   //获取当前线程的名称
                
                System.out.println(name+"正在发售第"+  tickets--  +"张票");  
                
               }else {
                  break;
               }
            } catch (InterruptedException e) {
                
                e.printStackTrace();
            }    
        }
    }
}

public static void main(String[] args) {  
        
        Ticket ticket= new Ticket();               //创建线程任务
        
        Thread t1 = new Thread(ticket,"窗口1");    // 定义4个线程对象，代表4个售票窗口
        Thread t2 = new Thread(ticket,"窗口2");
        Thread t3 = new Thread(ticket,"窗口3");
        Thread t4 = new Thread(ticket,"窗口4");
        
        t1.start();  //开启四个线程
        t2.start();
        t3.start();
        t4.start();
        
         
    }

public class Ticket implements Runnable {    //解决线程安全问题，使用 同步代码块（同步锁）
    private int tickets=100;
    public void run() {
        while(true) {   
            synchronized(this) {  //将this设置为 锁对象
            try {
                if(tickets>0) {     
                Thread.sleep(10);   //使线程休眠
            
                String name=Thread.currentThread().getName();   //获取当前线程的名称
                
                System.out.println(name+"正在发售第"+  tickets--  +"张票");  
               }else {
                  break;
               }
            } catch (InterruptedException e) {
                e.printStackTrace();
            }
        }
      }
    }
}

public static void main(String[] args) {  
        
        Ticket ticket= new Ticket();//创建线程任务
        
        // 定义4个线程对象，代表4个售票窗口
        Thread t1 = new Thread(ticket,"窗口1");    
        Thread t2 = new Thread(ticket,"窗口2");
        Thread t3 = new Thread(ticket,"窗口3");
        Thread t4 = new Thread(ticket,"窗口4");
        
        //开启四个线程
        t1.start();  
        t2.start();
        t3.start();
        t4.start();
    }

public class Ticket implements Runnable {    //解决线程安全问题  使用 同步方法             
    private int tickets=100;
    public void run() {
        while(true) {  
            saleTicket();     //调用售票方法
            if(tickets<=0) {
                break;
            }
        }
    }
    private synchronized void saleTicket() {   //定义一个同步方法  saleTicket() 
        if(tickets>0) {
        try {
            if(tickets>0) {     
            Thread.sleep(10);                                //使线程休眠10ms
            String name=Thread.currentThread().getName();   //获取当前线程的名称
            System.out.println(name+"正在发售第"+  tickets--  +"张票");  
           }
        } catch (InterruptedException e) {
            e.printStackTrace();
        }    
     }
    }
}

    public static void main(String[] args) {  
        Ticket ticket= new Ticket();               //创建线程任务
        Thread t1 = new Thread(ticket,"窗口1");    // 定义4个线程对象，代表4个售票窗口
        Thread t2 = new Thread(ticket,"窗口2");
        Thread t3 = new Thread(ticket,"窗口3");
        Thread t4 = new Thread(ticket,"窗口4");
        t1.start();  //开启四个线程
        t2.start();
        t3.start();
        t4.start();
    }