Java基础知识(十一)--多线程

class Printer {
 public static void print1() {
  synchronized(Printer.class){    //锁对象可以是任意对象,但是被锁的代码需要保证是同一把锁,不能用匿名对象
   System.out.print("程");
   System.out.print("序");
   System.out.print("员");
   System.out.print("\r\n");
  }
 }
 /*
  * 非静态同步函数的锁是:this
  * 静态的同步函数的锁是:字节码对象
  */
 public static synchronized void print2() { 
  System.out.print("码");
  System.out.print("农");
  System.out.print("\r\n");
 }
}

public class Demo2_Synchronized {

  /**
   * @param args
   * 需求:铁路售票,一共100张,通过四个窗口卖完.
   */
  public static void main(String[] args) {
   TicketsSeller t1 = new TicketsSeller();
   TicketsSeller t2 = new TicketsSeller();
   TicketsSeller t3 = new TicketsSeller();
   TicketsSeller t4 = new TicketsSeller();
   
   t1.setName("窗口1");
   t2.setName("窗口2");
   t3.setName("窗口3");
   t4.setName("窗口4");
   t1.start();
   t2.start();
   t3.start();
   t4.start();
  }
 
 }
 
 class TicketsSeller extends Thread {
  private static int tickets = 100;
  static Object obj = new Object();
  public TicketsSeller() {
   super();
   
  }
  public TicketsSeller(String name) {
   super(name);
  }
  public void run() {
   while(true) {
    synchronized(obj) {
     if(tickets <= 0) 
      break;
     try {
      Thread.sleep(10);//线程1睡,线程2睡,线程3睡,线程4睡
     } catch (InterruptedException e) {
      
      e.printStackTrace();
     }
     System.out.println(getName() + "...这是第" + tickets-- + "号票");
    }
   }
  }
 }

//饿汉式
class Singleton {
  //1,私有构造函数
  private Singleton(){}
  //2,创建本类对象
  private static Singleton s = new Singleton();
  //3,对外提供公共的访问方法
  public static Singleton getInstance() {
    return s;
  }

  public static void print() {
    System.out.println("11111111111");
  }
}

//懒汉式,单例的延迟加载模式
class Singleton {
 //1,私有构造函数
 private Singleton(){}
 //2,声明一个本类的引用
 private static Singleton s;
 //3,对外提供公共的访问方法
 public static Singleton getInstance() {
  if(s == null)
   //线程1,线程2
   s = new Singleton();
  return s;
 }
 
 public static void print() {
  System.out.println("11111111111");
 }
}

class Singleton {
  private Singleton() {}

  public static final Singleton s = new Singleton();//final是最终的意思,被final修饰的变量不可以被更改
}