java基础---->java多线程的使用（十）

　　这里介绍一下java中关于线程状态的知识，主要通过代码演示各种状态出现的时机。少年时我们追求激情，成熟后却迷恋平庸，在我们寻找，伤害，背离之后，还能一如既往的相信爱情，这是一种勇气。每个人都有属于自己的一片森林，迷失的人迷失了，相逢的人会再相逢。

java多线程的状态

　　在java1.5中，Thread.State枚举类包含了线程的所有状态。以下是jdk关于线程的几种状态的说明：

1、NEW：A thread that has not yet started is in this state. 

2、RUNNABLE：A thread executing in the Java virtual machine is in this state. 

3、BLOCKED：A thread that is blocked waiting for a monitor lock is in this state. 

4、WAITING：A thread that is waiting indefinitely for another thread to perform a particular action is in this state. 

5、TIMED_WAITING：A thread that is waiting for another thread to perform an action for up to a specified waiting time is in this state. 

6、TERMINATED：A thread that has exited is in this state. 

以下我们通过代码来看一下各个状态切换出现的场景。

一、NEW、RUNNABLE、TERMINATED状态

package com.linux.huhx.thread3.threadState_1;

/**
 * @Author: huhx
 * @Date: 2017-10-31 下午 2:44
 * State: NEW, RUNNABLE, TERMINATED
 */
public class StateRun1 {
    public static void main(String[] args) throws InterruptedException {
        MyThread myThread = new MyThread();
        System.out.println("name " + Thread.currentThread().getName() + " 1 " + myThread.getState()); // name main 1 NEW
        Thread.sleep(1000);
        myThread.start();
        Thread.sleep(1000);
        System.out.println("name " + Thread.currentThread().getName() + " 2 " + myThread.getState()); // name main 2 TERMINATED
    }
}

class MyThread extends Thread {

    public MyThread() {
        System.out.println("name " + Thread.currentThread().getName() + " constructor " + Thread.currentThread().getState()); // name main constructor RUNNABLE
    }

    @Override
    public void run() {
        System.out.println("name " + Thread.currentThread().getName() + " run method " + Thread.currentThread().getState()); // name Thread-0 run method RUNNABLE
    }
}
/*
name main constructor RUNNABLE
name main 1 NEW
name Thread-0 run method RUNNABLE
name main 2 TERMINATED
 */

二、TIMED_WAITING状态

package com.linux.huhx.thread3.threadState_1;

/**
 * @Author: huhx
 * @Date: 2017-10-31 下午 2:51
 * STATE: TIMED_WAITING
 */
public class StateRun2 {

    public static void main(String[] args) throws InterruptedException {
        MyThread myThread = new MyThread();
        myThread.start();
        Thread.sleep(1000);
        System.out.println("main " + myThread.getState()); // main TIMED_WAITING
    }

    static class MyThread extends Thread {
        @Override
        public void run() {
            try {
                System.out.println("begin sleep.");
                Thread.sleep(10 * 1000);
                System.out.println("end sleep." + Thread.currentThread().getState()); // RUNNABLE
            } catch (InterruptedException e) {
                e.printStackTrace();
            }
        }
    }
}
/*
begin sleep.
main TIMED_WAITING
end sleep.RUNNABLE
 */

三、TIMED_WAITING, BLOCKED状态

package com.linux.huhx.thread3.threadState_1;

import java.util.concurrent.TimeUnit;

/**
 * @Author: huhx
 * @Date: 2017-10-31 下午 2:57
 * STATE: TIMED_WAITING, BLOCKED
 */
public class StateRun3 {

    public static void main(String[] args) throws InterruptedException {
        Thread1 threadA = new Thread1();
        threadA.setName("A");
        threadA.start();

        Thread2 threadB = new Thread2();
        threadB.setName("B");
        threadB.start();

        TimeUnit.SECONDS.sleep(2);
        System.out.println("In main threadB " + threadB.getState());
        System.out.println("In main threadA " + threadA.getState());
    }

    static class Thread1 extends Thread {
        @Override
        public void run() {
            Service.serviceMethod();
        }
    }

    static class Thread2 extends Thread {
        @Override
        public void run() {
            Service.serviceMethod();
        }
    }
}

class Service {
    public synchronized static void serviceMethod() {
        try {
            System.out.println(Thread.currentThread().getName() + " enter service method.");
            TimeUnit.SECONDS.sleep(10);
        } catch (InterruptedException e) {
            e.printStackTrace();
        }
    }
}
/*
A enter service method.
In main threadB BLOCKED
In main threadA TIMED_WAITING
B enter service method.
 */

四、WAITING状态

package com.linux.huhx.thread3.threadState_1;

import com.linux.huhx.thread2.ThreadB;

/**
 * @Author: huhx
 * @Date: 2017-10-31 下午 3:11
 * STATE: WAITING
 */
public class StateRun4 {
    public static void main(String[] args) throws InterruptedException {
        MyThread myThread = new MyThread();
        myThread.start();
        Thread.sleep(1000);
        System.out.println("In main thread state: " + myThread.getState()); // WAITING

        new MyThreadB().start();
    }

    static class Lock {
        public static final Byte lock = new Byte("0");
    }

    static class MyThread extends Thread {
        @Override
        public void run() {
            try {
                synchronized (Lock.lock) {
                    System.out.println("before wait: " + Thread.currentThread().getState()); // RUNNABLE
                    Lock.lock.wait();
                    System.out.println("after wait: " + Thread.currentThread().getState()); // RUNNABLE
                }
            } catch (InterruptedException e) {
                e.printStackTrace();
            }
        }
    }

    static class MyThreadB extends Thread {
        @Override
        public void run() {
            synchronized (Lock.lock) {
                Lock.lock.notify();
            }
        }
    }
}
/*
before wait: RUNNABLE
In main thread state: WAITING
after wait: RUNNABLE
 */

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