Java线程
[TOC]
4. Java线程
4.1.
4.1.1. 线程的状态
1. 就操作系统层面来说，线程状态有五种：
● 新建状态new：创建一个新线程
● 就绪状态ready：启动该线程，此时可以CPU调度
● 运行状态running：此时CPU调用其并执行其任务
● 等待状态waiting：因为sleep、join等方法无法继续执行，但还没执行完，就进入等待状态
● 结束状态terminated：任务执行完毕，线程结束
2. 就Java层面来说状态有六种：
● 新建状态NEW：创建一个新线程
● 就绪/运行状态RUNNABLE：启动线程后进入可运行状态，此时可能正在被执行，可能不在执行中
● 阻塞状态BLOCKED：一般拿锁失败会进入阻塞状态，等待锁的释放
● 等待状态WAITING：可能是挂起线程池、wait方法、awiat方法等，需要手动唤醒
● 时间等待状态TIMED_WAITING：可能是sleep方法、join方法等，不需要手动唤醒
● 结束状态TERMINATED：线程执行完毕
// new:public static void main(String[] args) throws InterruptedException{ Thread t1 = new Thread(() => { }); System.out.println(t1.getState());}// runnable:public static void main(String[] args) throws InterruptedException{ Thread t1 = new Thread(() => { while(true){} }); t1.start(); Thread.sleep(500); System.out.println(t1.getState());}// blocked:public static void main(String[] args) throws InterruptedException{ Object obj = new Object(); Thread t1 = new Thread(() => { synchronized(obj){} }); //main线程拿到了锁 synchronized(obj){ t1.start(); Thread.sleep(500); System.out.println(t1.getState()); }}// waiting:public static void main(String[] args) throws InterruptedException{ Object obj = new Object(); Thread t1 = new Thread(() => { synchronized(obj){ try{ obj.wait(); } catch (InterruptedException e){ e.printStackTrace(); } } }); t1.start(); Thread.sleep(500); System.out.println(t1.getState());}// timed_waiting:public static void main(String[] args) throws InterruptedException{ Thread t1 = new Thread(() => { try{ Thread.sleep(1000); } catch (InterruputedException e){ e.printStackTrace(); } }); t1.start(); Thread.sleep(500); System.out.println(t1.getState());}// terminated:public static void main(String[] args) throws InterruptedException{ Thread t1 = new Thread(() => { try{ Thread.sleep(500); } catch (InterruputedException e){ e.printStackTrace(); } }); t1.start(); Thread.sleep(1000); System.out.println(t1.getState());}