线程创建

方式一，继承Thread

public class MyThread extends Thread{
    @Override
    public void run() {
        System.out.println("thread ........");
    }
}
        
public class Test {
    public static void main(String[] args) {
        new MyThread().start();
    }
}

方式二、实现Runnable接口

1、普通方式

public class Test {
    public static void main(String[] args) {
        new Thread(new MyThread()).start();
    }
}
class MyThread implements Runnable{
    @Override
    public void run() {
        System.out.println("thread ........");
    }
}

2、匿名内部类

public class Test1 {
    public static void main(String[] args) {
        new Thread(new Runnable() {
            @Override
            public void run() {
                System.out.println("thread ........");
            }
        }).start();
    }
}

3、lambda方式（推荐）

public class Test1 {
    public static void main(String[] args) {
        new Thread(()->{
                System.out.println("thread ........");
        }).start();
    }
}

方式三、实现Callable接口

01、普通方式

public class Test1 {
    public static void main(String[] args) throws ExecutionException, InterruptedException {
        Callable<String> callable=new MyThread();
        FutureTask<String> task=new FutureTask<>(callable);
        new Thread(task).start();
        String result=task.get();
        System.out.println(result);
    }
}

class MyThread implements Callable<String> {
    @Override
    public String call() throws Exception {
        return "callable";
    }
}

02、匿名内部类

public class Test1 {
    public static void main(String[] args) throws ExecutionException, InterruptedException {
        FutureTask<String> task=new FutureTask<>(new Callable<String>() {
            @Override
            public String call() throws Exception {
                return "callable";
            }
        });
        new Thread(task).start();
        String result=task.get();
        System.out.println(result);
    }
}

03、lambda方式（推荐）

public class Test1 {
    public static void main(String[] args) throws ExecutionException, InterruptedException {
        FutureTask<String> task=new FutureTask<>(()->{
                System.out.println("........");
                return "callable";
        });
        new Thread(task).start();
        String result=task.get();
        System.out.println(result);
    }
}

方式四、线程池

1、普通方式

//有返回值,Callable
public class Test1 {
    public static void main(String[] args) throws ExecutionException, InterruptedException {
        ExecutorService executorService=Executors.newFixedThreadPool(2);
        Future<String> future=executorService.submit(new MyThread());
        System.out.println(future.get());
    }
}
class MyThread implements Callable<String>{
    @Override
    public String call() throws Exception {
        return "callable";
    }
}

2、匿名内部类

//无返回值,Runnable
public class Test1 {
    public static void main(String[] args) throws ExecutionException, InterruptedException {
        ExecutorService executorService=Executors.newFixedThreadPool(2);
        executorService.execute(new Runnable() {
            @Override
            public void run() {
                System.out.println("................");
            }
        });
    }
}

3、lambda方式（推荐）

public class Test1 {
    public static void main(String[] args) throws ExecutionException, InterruptedException {
        ExecutorService executorService=Executors.newFixedThreadPool(2);
        final String[] result = {"test result"};
        Future<String> future=executorService.submit(()->{
            System.out.println("......");
            result[0] ="sddssdf";
        }, result[0]);
        System.out.println(future.get());
    }
}

线程创建流程

sequenceDiagram
JVM->>OS: 申请创建线程
OS-->>OS: 开辟内存，创建Thread对象
OS-->>OS: 调度Thread对象
OS->>JVM: 执行成功