【JavaEE】Java 线程的几种状态

曾经终败给现在 2024-03-30 11:27 82阅读 0赞

**目录**

一、线程状态的种类及含义

二、线程状态间的切换条件

（1）使用isAlive()判断线程的存活状态

（2）关于BLOCKED、WAITING、TIMED\_WAITING状态之间的转换

1.TIMED\_WAITING

2.WAITING

3.BLOCKED

4.jconsole.exe的使用方式

--------------------

## 一、线程状态的种类及含义 ##

线程的状态是个枚举类型Thread.State

public class ThreadState{
        public static void main(String []args){
            for(Thread.State state:Thread.State.values()){
                System.out.println(state);
            }
        }
    }

![07999159bc704b8e88ed0ac4a6cda736.png][]

**1.NEW：安排了工作，还未开始行动**

**2.RUNNABLE:可工作的，分成正在工作中和即将开始工作。类似于进程中的就绪和运行状态。**

**3.BLOCKED:表示排队等待其他事情。同步阻塞，因为资源竞争而引起的阻塞。**

**4.WAITING:表示排队等待其他事情。等待阻塞，join()，需要其他线程唤醒。**

**5.TIMED\_WAITING:表示排队等待其他事情。计时等待阻塞，有一定的等待时间。**

**6.TERMINATED:工作完成。**

##    二、线程状态间的切换条件 ##

![aa5be42777af4c3ab42fbd9a6217b5ce.png][]

### （1）使用isAlive()判断线程的存活状态 ###

public class ThreadStateTransfer {
        public static void main(String[] args) throws InterruptedException {
            Thread t = new Thread(() -> {
                for (int i = 0; i <1; i++) {
                }
            }, "线程一");
            System.out.println(t.getName() + ": " + t.getState());
            t.start();
            while (t.isAlive()) {
                System.out.println(t.getName() + ": " + t.getState());
            }
            System.out.println(t.getName() + ": " + t.getState());;
        }
    }

![d26fa12b765a4a3a871c2b275afb0319.png][]

### （2）关于BLOCKED、WAITING、TIMED\_WAITING状态之间的转换 ###

#### 1.TIMED\_WAITING ####

public class ThreadStateTransfer {
        public static void main(String[] args) {
            final Object object = new Object();
            Thread t1 = new Thread(new Runnable() {
                @Override
                public void run() {
                    synchronized (object) {
                        while (true) {
                            try {
                                Thread.sleep(1000);
                            } catch (InterruptedException e) {
                                e.printStackTrace();
                            }
                        }
                    }
                }
            }, "t1");
            t1.start();
            Thread t2 = new Thread(new Runnable() {
                @Override
                public void run() {
                    synchronized (object) {
                        System.out.println("hehe");
                    }
                }
            }, "t2");
            t2.start();
        }
    }

![e18c877c81ef475cb2afc7cdeafb51f4.png][]

![8ae71024b8e040759cf82c3ea6454db1.png][]

代码中使用Thread.sleep（10000），此时线程t1是TIMED\_WAITING状态，而t2则是BLOCKED转态。

#### 2.WAITING ####

public class ThreadStateTransfer {
        public static void main(String[] args) {
            final Object object = new Object();
            Thread t1 = new Thread(new Runnable() {
                @Override
                public void run() {
                  synchronized (object) {
                        while (true) {
                            try {
                                object.wait();
                            } catch (InterruptedException e) {
                                e.printStackTrace();
                            }
                        }
                    }
                }
            }, "t1");
            t1.start();
            Thread t2 = new Thread(new Runnable() {
                @Override
                public void run() {
                     synchronized (object) {
                        System.out.println("hehe");
                    }
                }
            }, "t2");
            t2.start();
        }
    }

![e1c8ec6fcbf8466d8e5133cfeabff3d3.png][]

代码中使用object.wait()，此时线程t1是WAITING状态。

**总结而言：BLOCKED 表示等待获取锁, WAITING 和 TIMED\_WAITING 表示等待其他线程发来通知。TIMED\_WAITING 线程在等待唤醒，但设置了时限; WAITING 线程在无限等待唤醒。**

#### 3.BLOCKED ####

#### 4.jconsole.exe的使用方式 ####

在本机下载jdk的文件中打开bin目录找到当中的jconsole.exe 文件，这是java中自带的调试，点击连接。可以查看线程t1、t2的状态。

![182c993a5dda4185a27e8e26239b0224.png][]

![bcd1080c602d4df7970e309c94cc2d1b.png][]

![f0e9c1043dcd4ecd97eb8618039637ab.png][]

![2afc5f6edeb543f9a7ee3f40a0af2056.png][]

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