线程安全的单例模式

package com.thread;

public class Test8 {
    public static void main(String[] args) {
        MyThread t1 = new MyThread();
        MyThread t2 = new MyThread();
        MyThread t3 = new MyThread();
        
        t1.start();
        t2.start();
        t3.start();
        
    }
}

class MyObject{
    private static MyObject myObject = new MyObject();
    
     public static MyObject getInstance(){
        return myObject;
    }
}

class MyThread extends Thread{
    public void run(){
        System.out.println(MyObject.getInstance().hashCode());
    }
}

package com.thread;

public class Test5 {
    public static void main(String[] args) {
        MyThread t1 = new MyThread();
        MyThread t2 = new MyThread();
        MyThread t3 = new MyThread();
        
        t1.start();
        t2.start();
        t3.start();
        
    }
}

class MyObject{
    private static MyObject myObject;
    
     public static MyObject getInstance(){
        
        if(myObject==null){
            try {
                Thread.sleep(3000);
            } catch (InterruptedException e) {
                // TODO Auto-generated catch block
                e.printStackTrace();
            }
             synchronized (MyObject.class) {
                 if(myObject == null){
                     myObject = new MyObject();    
                     System.out.println(Thread.currentThread().getName()+" 新建实例");
                 }
                
            }
            
            
        }
        return myObject;
    }
}

class MyThread extends Thread{
    public void run(){
        System.out.println(MyObject.getInstance().hashCode());
    }
}

package com.thread;

public class Test6 {
    public static void main(String[] args) {
        MyThread t1 = new MyThread();
        MyThread t2 = new MyThread();
        MyThread t3 = new MyThread();
        
        t1.start();
        t2.start();
        t3.start();
        
    }

}

class MyObject{
    private static final long serivalizableUID = 888l;
    
    private static class MyobjectHandle{
        private static final MyObject myObject= new MyObject();
    }
    
    public static MyObject getInstance(){
        return MyobjectHandle.myObject;
    }
    
    
    
}

class MyThread extends Thread{
    public void run(){
        System.out.println(MyObject.getInstance().hashCode());
    }
}

package com.thread;

public class Test7 {
    public static void main(String[] args) {
        MyThread t1 = new MyThread();
        MyThread t2 = new MyThread();
        MyThread t3 = new MyThread();
        
        t1.start();
        t2.start();
        t3.start();
        
    }

}

class MyObject{
    
    private static MyObject instance = null;
    
    static{
        instance = new MyObject();
    }
    
    public static MyObject getInstance(){
        return instance;
    }
    
}

class MyThread extends Thread{
    public void run(){
        System.out.println(MyObject.getInstance().hashCode());
    }
}