JAVA ——线程概念（线程的生命周期及使用）

首先让我们了解一下java中线程的周期

分为几种状态：

• 新建 NEW
• 运行 RUNNING
• 阻塞 BLOCKING
• 死亡 DEAD
  

1. 继承Thread类
2. 实现Runnable接口
3. 实现Callable接口
4. 使用线程池

1.继承Thread类

class MyThread extends Thread{

    
    public void run() {
        for (int i = 0; i < 100; i++) {
            System.out.println(Thread.currentThread().getName() +"执行了" + i);
        }
    }
}

public class ThreadDemo {

    public static void main(String[] args) {
        //创建线程对象
        MyThread myThread = new MyThread();
        //启动线程
        myThread.start();
        //主线程执行
        for (int i = 0; i < 100; i++) {
            System.out.println(Thread.currentThread().getName() +"执行了" + i);
        }
    }
}

2.实现Runnable接口

class MyThread implements Runnable {
    public void run(){
        for (int i = 0; i < 100; i++) {
            System.out.println(Thread.currentThread().getName() + "线程" + i);
        }
    }
}

public class ThreadDemo {
    public static void main(String[] args) {
        //lambda表达式
        Thread thread1 = new Thread(()->{
            for (int i = 0; i < 100; i++) {
                System.out.println(Thread.currentThread().getName() + "线程" + i);
            }
        });

        //匿名内部类
        Thread thread = new Thread(new Runnable() {
            @Override
            public void run() {
                for (int i = 0; i < 100; i++) {
                    System.out.println(Thread.currentThread().getName() + "线程" + i);
                }
            }
        });


        thread.start();
        thread1.start();
        for (int i = 0; i < 100; i++) {
            System.out.println(Thread.currentThread().getName() + "线程" + i);
        }
    }
}

3.实现Callable接口 注意：调用get方法得到返回结果

class MyCallable implements Callable {
    @Override
    public Long call() throws Exception {
        long sum = 0;
        for (long i = 0; i < 10000000; i++) {
            sum += i;
        }
        System.out.println(sum);
        return sum;
    }

}

public class CallableDemo {
    public static void main(String[] args) {
        //普通方式
        FutureTask futureTask = new FutureTask<>(new MyCallable());

        //lambda表达式方式
        FutureTask futureTask1 = new FutureTask(() ->{
            long sum = 0;
            for (long i = 0; i < 10000000; i++) {
                sum += i;
            }
            System.out.println(sum);
            return sum;
        });
        new Thread(futureTask).start();
        new Thread(futureTask1).start();
        System.out.println("等待结束");
    }
}

一些关于线程的小练习

public class Demo1 {
    public static void main(String[] args) {
        //1~100内偶数
        Thread t1 = new Thread(() -> {
            for (int i = 1; i < 100; i++) {
                if (i % 2 == 0) {
                    System.out.println("线程1---偶数:" + i);
                }
            }
        });

        //1~100内奇数
        Thread t2 = new Thread(()->{
            for (int i = 1; i < 100; i++) {
                if (i % 2 != 0){
                    System.out.println("线程2---奇数:" + i);
                }
            }
        });

        t1.setPriority(8);
        t2.setPriority(3);

        t1.start();
        t2.start();
    }
}


public class Demo2 {
    public static void getFiles(String p) {
        StringBuilder path = new StringBuilder(p).append("/");
        File file = new File(path.toString());
        File[] tempList = file.listFiles();
        //遍历该目录下所有东西
        for (int i = 0; i < tempList.length; i++) {
            //如果是文件，就读取并打印
            if (tempList[i].isFile()) {
                print(new File(path + tempList[i].getName()));
                System.out.println(tempList[i].getName());
            }
        }
    }

    //写一个IO流读取文件的方法
    public static void print(File file){
        //要读取的目标文件
        FileReader fr = null;
        try {
            fr = new FileReader(file);
            char[] chars = new char[1024];
            int len;
            while ((len = fr.read(chars)) != -1){
                String s = new String(chars, 0, len);
                System.out.println(s);
            }
        } catch (Exception e) {
            e.printStackTrace();
        }
    }

    public static void main(String[] args) {
        Thread t1 = new Thread(() -> getFiles("D:\111\java4\src") );
        t1.start();
    }
}


public class Demo3 {
    public static void main(String[] args) {
        for (int i = 1; i < 89; i++) {
            System.out.println("播放第" + i + "集");
            if (i == 10){
                Thread thread = new Thread(() -> System.out.println("快递到了,去拿快递"));
                thread.start();
                try {
                    //注意：join之前,一定要将线程处于准备状态start
                    thread.join();
                } catch (InterruptedException e) {
                    e.printStackTrace();
                }
            }
        }
    }
}



public class Demo4 {
    public static void main(String[] args) {
        int destination = 1000;
        new Thread(() -> {
            for (int i = destination; i != 0; i-=5) {
                if(i % 20 == 0 && i != destination){
                    try {
                        System.out.println("兔子累了，距离终点" + i);
                        Thread.sleep(500);
                    } catch (InterruptedException e) {
                        e.printStackTrace();
                    }
                }
            }
            System.out.println("兔子获胜");
            System.exit(0);
        }).start();

        new Thread(() -> {
            for (int i = destination; i != 0; i-=1) {
                if(i % 100 == 0 && i != destination){
                    try {
                        System.out.println("乌龟累了，距离终点" + i);
                        Thread.sleep(500);
                    } catch (InterruptedException e) {
                        e.printStackTrace();
                    }
                }
            }
            System.out.println("乌龟获胜");
            System.exit(0);
        }).start();
    }

}