JAVA单排日记-2020/1/18-1-多线程_创建多线程

1.创建多线程的第一种方式

1. 创建一个Thread子类
2. 子类中重写run方法，设置线程任务
3. 主程序中创建Thread的子类对象
4. 调用Thread中的star方法，开启多线程

线程1：

public class Thread01 extends Thread {
    @Override
    public void run() {
        for (int i = 0; i <3; i++) {
            System.out.println("线程1");
        }
    }
}

线程2：

public class Thread02 extends Thread {
    @Override
    public void run() {
        for (int i = 0; i <3; i++) {
            System.out.println("线程2");
        }
    }
}

主程序：

public class Demo01Thread {
    public static void main(String[] args) {
        Thread thread01 = new Thread01();
        Thread thread02 = new Thread02();

        thread01.start();
        thread02.start();
    }
}

检验多线程的好处：一个线程停止不会影响其他线程

import java.util.Objects;

public class Thread01 extends Thread {
    @Override
    public void run() {
        Objects.requireNonNull(null);
        for (int i = 0; i <3; i++) {
            System.out.println("线程1");
        }
    }
}

2.多线程的运行原理

3.多线程内存图解

4.Thread类中常用方法

• 获取线程名称

1. getName()
2. currentThread()

public class MyThread extends Thread {
    @Override
    public void run() {
        System.out.println(getName());
    }
}

public class Demo01 {
    public static void main(String[] args) {
        Thread one = new MyThread();
        one.start();
    }
}

public class MyThread extends Thread {
    @Override
    public void run() {
        System.out.println(currentThread().getName());
    }
}

public class Demo01 {
    public static void main(String[] args) {
        new MyThread().start();
        new MyThread().start();
        new MyThread().start();
    }
}

• 设置线程名称

1. setName()
2. 子类中创建带参构造方法

public class MyThread extends Thread {
    @Override
    public void run() {
        System.out.println(currentThread().getName());
    }
}

public class Demo01 {
    public static void main(String[] args) {
        Thread one = new MyThread();
        one.setName("线程1");
        one.start();
    }
}

public class MyThread extends Thread {
    public MyThread(String name) {
        super(name);
    }

    @Override
    public void run() {
        System.out.println(currentThread().getName());
    }
}

public class Demo01 {
    public static void main(String[] args) {
        Thread one = new MyThread("线程2");
        one.start();
    }
}

• 正在执行的线程暂停指定毫秒数sleep

public class Demo03 {
    public static void main(String[] args) throws InterruptedException {
        for (int i = 0; i <30; i++) {
            System.out.println(i);
            Thread.sleep(1000);
        }
    }
}

5.创建多线程的第二种方式

• 步骤

1. 创建一个Runnable接口的实现类
2. 在实现类中重写Runnable接口的run()方法
3. 主程序中创建一个Runnable接口的实现类对象
4. 创建Thread类对象，构造方法中放入Runnable接口的实现类对象
5. 调用Thread中的star方法，开启多线程

public class ImpRunnable01 implements Runnable {
    @Override
    public void run() {
        for (int i = 0; i <3; i++) {
            System.out.println(Thread.currentThread().getName()+"--->"+i);
        }
    }
}

public class DemoRunnable {
    public static void main(String[] args) {
        Runnable run = new ImpRunnable01();

        Thread one = new Thread(run);
        Thread two = new Thread(run);

        one.start();
        two.start();
    }
}

• 优点
  

6.匿名内部类实现多线程的创建（程序的简化）

public class Demo04 {
    public static void main(String[] args) {
        Thread one = new Thread(){
            @Override
            public void run() {
                for (int i = 0; i <4; i++) {
                    System.out.println(getName()+"--->"+i);
                }
            }
        };

        one.start();
    }
}

public class Demo05 {
    public static void main(String[] args) {
        Runnable one = new Runnable() {
            @Override
            public void run() {
                for (int i = 0; i <4; i++) {
                    System.out.println(Thread.currentThread().getName()+"-->"+i);
                }
            }
        };
        
        new Thread(one).start();
    }
}