Java 线程基础实战

深碍√TFBOYSˉ_ 2021-07-24 12:44 271阅读 0赞

# 一 Java 线程状态 #

## 1 图解 ##

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L2NoZW5ncWl1bWluZw_size_16_color_FFFFFF_t_70][]

## 2 代码 ##

package com.mashibing.juc.c_000;
    
    // 线程的状态
    public class T04_ThreadState {
        static class MyThread extends Thread {
            @Override
            public void run() {
                System.out.println(this.getState());
                for(int i=0; i<10; i++) {
                    try {
                        Thread.sleep(500);
                    } catch (InterruptedException e) {
                        e.printStackTrace();
                    }
                    System.out.println(i);
                }
            }
        }
    
    
        public static void main(String[] args) {
            Thread t = new MyThread();
            System.out.println(t.getState());
            t.start();
            try {
                t.join();
            } catch (InterruptedException e) {
                e.printStackTrace();
            }
            System.out.println(t.getState());
        }
    }

## 3 测试 ##

NEW
    RUNNABLE
    0
    1
    2
    3
    4
    5
    6
    7
    8
    9
    TERMINATED

# 二 方法调用和启动线程区别 #

## 1 代码 ##

package com.mashibing.juc.c_000;
    
    import java.util.concurrent.TimeUnit;
    
    public class T01_WhatIsThread {
        private static class T1 extends Thread {
            @Override
            public void run() {
                for (int i = 0; i < 10; i++) {
                    try {
                        TimeUnit.MICROSECONDS.sleep(1);
                    } catch (InterruptedException e) {
                        e.printStackTrace();
                    }
                    System.out.println("T1");
                }
            }
        }
    
        public static void main(String[] args) {
            // new T1().run(); // 方法调用
            new T1().start(); // 启动一个新线程
            for (int i = 0; i < 10; i++) {
                try {
                    TimeUnit.MICROSECONDS.sleep(1);
                } catch (InterruptedException e) {
                    e.printStackTrace();
                }
                System.out.println("main");
            }
        }
    }

## 2 方法调用测试 ##

T1
    T1
    T1
    T1
    T1
    T1
    T1
    T1
    T1
    T1
    main
    main
    main
    main
    main
    main
    main
    main
    main
    main

## 3 启动线程测试 ##

T1
    main
    T1
    main
    T1
    main
    T1
    main
    T1
    main
    T1
    main
    T1
    main
    main
    T1
    T1
    main
    main
    T1

# 三 创建和启动线程 #

## 1 代码 ##

package com.mashibing.juc.c_000;
    
    // 创建和启动线程
    public class T02_HowToCreateThread {
        static class MyThread extends Thread {
            @Override
            public void run() {
                System.out.println("Hello MyThread!");
            }
        }
    
    
        static class MyRun implements Runnable {
            @Override
            public void run() {
                System.out.println("Hello MyRun!");
            }
        }
    
    
        public static void main(String[] args) {
            new MyThread().start(); // 通过继承 Thread 创建和启动线程
            new Thread(new MyRun()).start(); // 通过实现 Runnable 创建和启动线程
            new Thread(() -> {
                System.out.println("Hello Lambda!");
            }).start(); // 通过 Lambda 表达式创建和启动线程，它实际是第2种的变形
        }
    }
    // 启动线程的三种方式
    // 1：Thread
    // 2：Runnable
    // 3：Executors.newCachedThread 通过线程池启动线程

## 2 测试 ##

Hello MyThread!
    Hello MyRun!
    Hello Lambda!

# 四 线程的几个常用方法 #

## 1 点睛 ##

sleep：当前线程睡眠一段时间，让给其他线程去执行。

yield：当前线程非常谦让地退出一下，进入到就绪状态，随时可能再次运行。

join：比如在t2线程中，调用t1.join。它的意思是，让t1线程先运行完，然后继续执行t2线程。它的应用场景：等待另外一个线程的结束。

## 2 代码 ##

package com.mashibing.juc.c_000;
    
    // 测试线程的几个常用方法
    public class T03_Sleep_Yield_Join {
        public static void main(String[] args) {
            testSleep();
            //testYield();
            //testJoin();
        }
    
        static void testSleep() {
            new Thread(() -> {
                for (int i = 0; i < 10; i++) {
                    System.out.println("A" + i);
                    try {
                        Thread.sleep(500);
                        //TimeUnit.Milliseconds.sleep(500)
                    } catch (InterruptedException e) {
                        e.printStackTrace();
                    }
                }
            }).start();
        }
    
        static void testYield() {
            new Thread(() -> {
                for (int i = 0; i < 10; i++) {
                    System.out.println("A" + i);
                    if (i % 2 == 0) Thread.yield();
                }
            }).start();
    
    
            new Thread(() -> {
                for (int i = 0; i < 10; i++) {
                    System.out.println("------------B" + i);
                    if (i % 2 == 0) Thread.yield();
                }
            }).start();
        }
    
        static void testJoin() {
            Thread t1 = new Thread(() -> {
                for (int i = 0; i < 10; i++) {
                    System.out.println("A" + i);
                    try {
                        Thread.sleep(500);
                        //TimeUnit.Milliseconds.sleep(500)
                    } catch (InterruptedException e) {
                        e.printStackTrace();
                    }
                }
            });
    
            Thread t2 = new Thread(() -> {
                try {
                    t1.join();
                } catch (InterruptedException e) {
                    e.printStackTrace();
                }
    
    
                for (int i = 0; i < 10; i++) {
                    System.out.println("B" + i);
                    try {
                        Thread.sleep(500);
                        //TimeUnit.Milliseconds.sleep(500)
                    } catch (InterruptedException e) {
                        e.printStackTrace();
                    }
                }
            });
            t1.start();
            t2.start();
        }
    }

## 3 测试 ##

a sleep 测试结果

> A0
> 
> A1
> 
> A2
> 
> A3
> 
> A4
> 
> A5
> 
> A6
> 
> A7
> 
> A8
> 
> A9

b yield 测试结果

> A0
> 
> A1
> 
> A2
> 
> A3
> 
> A4
> 
> \------------B0
> 
> A5
> 
> A6
> 
> A7
> 
> A8
> 
> A9
> 
> \------------B1
> 
> \------------B2
> 
> \------------B3
> 
> \------------B4
> 
> \------------B5
> 
> \------------B6
> 
> \------------B7
> 
> \------------B8
> 
> \------------B9

c join 测试结果

> A0
> 
> A1
> 
> A2
> 
> A3
> 
> A4
> 
> A5
> 
> A6
> 
> A7
> 
> A8
> 
> A9
> 
> B0
> 
> B1
> 
> B2
> 
> B3
> 
> B4
> 
> B5
> 
> B6
> 
> B7
> 
> B8
> 
> B9

[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L2NoZW5ncWl1bWluZw_size_16_color_FFFFFF_t_70]: /images/20210724/2b53969c717b4815a135c2996bfba23b.png