java創建線程方式

1.繼承Thread類

public class ThreadCreator extends Thread{

    public static void main(String[] args) {
       //第一種方式：
       ThreadCreator creator = new ThreadCreator();
       Thread thread = new Thread(creator,"線程1");
       thread.start();
       //第二種方式：
       Thread thread = new ThreadCreator();
       thread.start();
       //第三種方式：
       new ThreadCreator().start();
　　　}
 
    @Override
    public void run() {
        System.out.println(Thread.currentThread().getName() + "run");
    }
}

2.實現Runnable介面

public class ThreadCreator implements Runnable{

    public static void main(String[] args) {
       ThreadCreator creator = new ThreadCreator();
       Thread thread = new Thread(creator,"線程1");
       thread.start();
    }

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

3.實現Callable介面

public class ThreadCreator implements Callable<Integer> {

    public static void main(String[] args) throws ExecutionException, InterruptedException {
       ThreadCreator creator = new ThreadCreator();
       FutureTask futureTask = new FutureTask(creator);
       Thread thread = new Thread(futureTask,"線程");
       thread.start();
       System.out.println(futureTask.get());
    }

    @Override
    public Integer call() {
        return 1024;
    }
}

4.線程池ExecutorService

public class ThreadCreator{

   static ExecutorService service = Executors.newFixedThreadPool(5);

    public static void main(String[] args) throws ExecutionException, InterruptedException {
        //execute無返回值
        service.execute(new ThreadTask(1,"1"));
        //submit有返回值
        Future<Integer> result = service.submit(new ThreadTaskCall());
        System.out.println(result.get());
        service.shutdownNow();
    }
    static class ThreadTask implements Runnable{
        private int param1;
        private String param2;
        public ThreadTask(int param3,String param4){
            this.param1 = param3;
            this.param2 = param4;
        }
        @Override
        public void run() {
            System.out.println(param1+param2);
        }
    }

    static class ThreadTaskCall implements Callable<Integer>{
        @Override
        public Integer call() throws Exception {
            return 1024;
        }
    }
}

線程池中submit和execute的區別：

     ① 可接受的任務類型不一樣：execute只能接受Runnable任務，submit還可以接受Callable任務。

     ② 返回值：execute無返回值，任務一旦提交，無法在當前線程中監控執行結果。submit有一個Future類型的返回值，用來接收返回值或響應異常。通過get()方法獲取。

submit底層還是調用的execute，只是在此基礎上用future封裝了一層，並將執行過程中產生的異常全部封裝在一個變數中：

public void run() {
        if (state != NEW ||
            !UNSAFE.compareAndSwapObject(this, runnerOffset,
                                         null, Thread.currentThread()))
            return;
        try {
            Callable<V> c = callable;
            if (c != null && state == NEW) {
                V result;
                boolean ran;
                try {
                    result = c.call();
                    ran = true;
                } catch (Throwable ex) {
                    result = null;
                    ran = false;
                    setException(ex);
                }
                if (ran)
                    set(result);
            }
        } finally {
            runner = null;
            int s = state;
            if (s >= INTERRUPTING)
                handlePossibleCancellationInterrupt(s);
        }
    }
protected void setException(Throwable t) {
        if (UNSAFE.compareAndSwapInt(this, stateOffset, NEW, COMPLETING)) {
            outcome = t;
            UNSAFE.putOrderedInt(this, stateOffset, EXCEPTIONAL); // final state
            finishCompletion();
        }
    }

另外，spring中的schedule註解借鑒使用了submit的處理方式。

5.匿名內部類

public class ThreadCreator {

    public static void main(String[] args) {

        //繼承Thread類
        new Thread() {
            @Override
            public void run() {
                System.out.println("extends Thread Class!");
            }
        }.start();
        //實現Runnable介面
        new Thread(new Runnable() {
            @Override
            public void run() {
                System.out.println("implement Runnable!");
            }
        }).start();
        //實現Callable介面
        new Thread(new FutureTask<Integer>(new Callable() {
            @Override
            public Integer call() throws Exception {
                return 1024;
            }
        })).start();
        //lambda表達式
        new Thread(() -> System.out.println("execute single code")).start();
        new Thread(() -> {
            System.out.println("execute multiple code");
        }).start();
    }
}

lambda線程池：

public class ThreadCreator {

    static ExecutorService service = Executors.newFixedThreadPool(5);

    static List list = new ArrayList();

    public static void main(String[] args) {
        service.execute(() -> execute()); //無返回值
        Future future = service.submit(() -> execute()); //有返回值
        list.add(future);
    }

    public static void execute() {
        //do something
    }
}