Java pause / suspend thread (suspend()) and resume thread (resume())

Suspend() and resume() methods

package ch14;
public class MyThread21 extends Thread
{
    private long i=0;
    public long getI()
    {
        return i;
    }
    public void setI(long i)
    {
        this.i=i;
    }
    @Override
    public void run()
    {
        while(true)
        {
            i++;
        }
    }
}

package ch14;
public class Test25
{
    public static void main(String[] args)
    {
        try
        {
            MyThread21 thread=new MyThread21();
            thread.start();
            Thread.sleep(5000);
            //A段
            thread.suspend();
            System.out.println("A= "+System.currentTimeMillis()+" i= "+thread.getI());
            Thread.sleep(5000);
            System.out.println("A= "+System.currentTimeMillis()+" i= "+thread.getI());
            //B段
            thread.resume();
            Thread.sleep(5000);
            //C段
            thread.suspend();
            System.out.println("B= "+System.currentTimeMillis()+" i= "+thread.getI());
            Thread.sleep(5000);
            System.out.println("B= "+System.currentTimeMillis()+" i= "+thread.getI());
        }
        catch(InterruptedException e)
        {
            e.printStackTrace();
        }
    }
}

A= 1540978346179 i= 2680986095
A= 1540978351179 i= 2680986095
B= 1540978356179 i= 5348657508
B= 1540978361179 i= 5348657508

Exclusive problem

Example 2

package ch14;
public class SynchronizedObject1
{
    synchronized public void printString()
    {
        System.out.println("begin");
        if (Thread.currentThread().getName().equals("a"))
        {
            System.out.println("a线程永远 suspend了！");
            Thread.currentThread().suspend();
        }
        System.out.println("end");
    }
}

package ch14;
public class Test26
{
    public static void main(String[] args)
    {
        try
        {
            final SynchronizedObject1 object=new SynchronizedObject1();
            Thread thread1=new Thread()
            {
                @Override
                public void run()
                {
                    object.printString();
                }
            };
            thread1.setName("a");
            thread1.start();
            Thread.sleep(1000);
            Thread thread2=new Thread()
            {
                @Override
                public void run()
                {
                    System.out.println("thread2启动了，但进入不了printString()方法！所以只会打印1个begin！");
                    System.out.println("因为printString()方法被a线程锁定并且永远暂停了！");
                    object.printString();
                }
            };
            thread2.start();
        }
        catch(InterruptedException e)
        {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
    }
}

begin
a线程永远 suspend了！
thread2启动了，但进入不了printString()方法！所以只会打印1个begin！
因为printString()方法被a线程锁定并且永远暂停了！

Example 3

package ch14;
public class MyThread22 extends Thread
{
    private long i=0;
    @Override
    public void run()
    {
        while (true)
        {
            i++;
        }
    }
}

package ch14;
public class Test27
{
    public static void main(String[] args)
    {
        try
        {
            MyThread22 thread=new MyThread22();
            thread.start();
            Thread.sleep(1000);
            thread.suspend();
            System.out.println("main end!");
        }
        catch(InterruptedException e)
        {
            e.printStackTrace();
        }
    }
}

main end!

package ch14;
public class MyThread22 extends Thread
{   
    private long i=0; 
    @Override 
    public void run()
    { 
        while(true)
        { 
            i++; 
            System.out.println(i); 
        } 
    }
}

......
130862
130863
130864
130865
130866
130867

Out of sync problem

Example 4

package ch14;
public class MyObject
{
    private String username="1";
    private String password="11";
    public void setValue(String u,String p)
    {
        this.username=u;
        if(Thread.currentThread().getName().equals("a"))
        {
            System.out.println("停止a线程！");
            Thread.currentThread().suspend();
        }
        this.password=p;
    }
    public void printUsernamePassword()
    {
        System.out.println(username+" "+password);
    }
}

package ch14;
public class Test28
{
    public static void main(String[] args) throws InterruptedException
    {
        final MyObject myobject=new MyObject();
        Thread thread1=new Thread()
        {
            public void run()
            {
                myobject.setValue("a","aa");
            };
        };
        thread1.setName("a");
        thread1.start();
        Thread.sleep(500);
        Thread thread2=new Thread()
        {
            public void run()
            {
                myobject.printUsernamePassword();
            };
        };
        thread2.start();
    }
}

停止a线程！
a 11