守护线程：垃圾回收（GC）线程

线程最大优先级10，最小优先级1，默认优先级5

线程的执行状态：新建、就绪、运行、阻塞、结束

start() 分配资源

run() 执行具体的用户线程代码；不是由用户程序来调用的，当调用start()方法启动一个线程之后，只要线程获得了CPU执行时间，便进入run()方法体执行具体的用户线程

run()为同步执行，失去了线程的意义

线程创建的方法：

一、继承Thread

package com.crazymakercircle.multithread.basic.create;
import personal.nien.javabook.util.Print;
public class CreateDemo {
public static final int MAX_TURN = 5;
public static String getCurThreadName() {
return Thread.currentThread().getName();
}
//线程的编号
static int threadNo = 1;
static class DemoThread extends Thread { //①
public DemoThread() {
super("DemoThread-" + threadNo++); //②
}
public void run() { //③
for (int i = 1; i < MAX_TURN; i++) {
Print.cfo(getName() + ", 轮次：" + i);
}
Print.cfo(getName() + " 运行结束.");
}
}
public static void main(String args[]) throws InterruptedException {
Thread thread = null;
//方法一：使用Thread子类创建和启动线程
for (int i = 0; i < 2; i++) {
thread = new DemoThread();
thread.start();
}
Print.cfo(getCurThreadName() + " 运行结束.");
}
}

二、实现Runnable 

Runnable逻辑和数据更好的分离，面向对象,避免单继承带来的局限性

package com.crazymakercircle.multithread.basic.create;
// 省略import
public class SalesDemo
{
public static final int MAX_AMOUNT = 5; //商品数量
//商店商品类（销售线程类），一个商品一个销售线程，每个线程异步销售4次
static class StoreGoods extends Thread
{
StoreGoods(String name)
{
super(name);
}
private int goodsAmount = MAX_AMOUNT;
public void run()
{
for (int i = 0; i <= MAX_AMOUNT; i++)
{
if (this.goodsAmount > 0)
{
Print.cfo(getCurThreadName() + " 卖出一件，还剩："
+ (--goodsAmount));
sleepMilliSeconds(10);
}
}
Print.cfo(getCurThreadName() + " 运行结束.");
}
}
//商场商品类（target销售线程的目标类），一个商品最多销售4次，可以多人销售
static class MallGoods implements Runnable
{
//多人销售可能导致数据出错，使用原子数据类型保障数据安全
private AtomicInteger goodsAmount = new AtomicInteger(MAX_AMOUNT);
public void run()
{
for (int i = 0; i <= MAX_AMOUNT; i++)
{
if (this.goodsAmount.get() > 0)
{
Print.cfo(getCurThreadName() + " 卖出一件，还剩："
+ (goodsAmount.decrementAndGet()));
sleepMilliSeconds(10);
}
}
Print.cfo(getCurThreadName() + " 运行结束.");
}
}
public static void main(String args[]) throws InterruptedException
{
Print.hint("商店版本的销售");
for (int i = 1; i <= 2; i++)
{
Thread thread = null;
thread = new StoreGoods("店员-" + i);
thread.start();
}
Thread.sleep(1000);
Print.hint("商场版本的销售");
MallGoods mallGoods = new MallGoods();
for (int i = 1; i <= 2; i++)
{
Thread thread = null;
thread = new Thread(mallGoods, "商场销售员-" + i);
thread.start();
}
Print.cfo(getCurThreadName() + " 运行结束.");
}
}

三、实现Callable

Callable有返回值

/*** Copyright (c) 2022,TravelSky.* All Rights Reserved.* TravelSky CONFIDENTIAL* 
* Project Name:ldpCoreCompApp* Package Name:PACKAGE_NAME* File Name:Test.java* Date:2022年08月2022/8/2日 10:01:14*/import java.util.concurrent.*;/*** ClassName: Test 
* Description: TODO 
* Date: 2022年08月2022/8/2日 10:01:14 
* 
** @author lixin(邮箱)** 修改记录* @version 产品版本信息 yyyy-mm-dd 姓名(邮箱) 修改信息
**/
public class Test {/*** 继承Thread*/static class TestThread extends Thread{@Overridepublic void run() {System.out.println("TestThread");}}/*** 实现Runnable*/static class TestRunnable implements Runnable{@Overridepublic void run() {System.out.println("TestRunnable");}}/*** 实现Callable*/static class TestCallable implements Callable {@Overridepublic String call() throws Exception {return "TestCallable";}}/*** 线程池创建*/private static ExecutorService executorService = Executors.newFixedThreadPool(3);static class TestExecutor implements Callable {@Overridepublic Long call() throws Exception {long startTime = System.currentTimeMillis();for (int i = 0; i < 5; i++){System.out.println(Thread.currentThread().getName()+" : "+i);Thread.sleep(100);}long used = System.currentTimeMillis() - startTime;return used;}}public static void main(String[] args) throws ExecutionException, InterruptedException {Thread thread = new TestThread();thread.start();Runnable runnable = new TestRunnable();Thread thread1 = new Thread(runnable);thread1.start();TestCallable testCallable = new TestCallable();FutureTask futureTask = new FutureTask(testCallable);Thread thread2 = new Thread(futureTask);thread2.start();System.out.println(futureTask.get());Future future = executorService.submit(new TestExecutor());System.out.println(future.get());}
}

四、线程池Executor

submit() 接收有返回值和无返回值的入参，有返回值

execute() 只接收无返回值的入参，无返回值