Question

如果我们在start方法而不是run方法中执行整个Thread功能会发生什么？下面的代码运行方式与在run方法中添加代码时运行的方式相同...

   public class RunMethodTest extends AppCompatActivity {


    @Override
    protected void onCreate(@Nullable Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        Abc abc=new Abc();
        abc.start();
    }
}

class Abc extends Thread
{
    @Override
    public synchronized void start() {
        super.start();
        for(int i=0;i<10;i++) {
            try {
                Thread.sleep(1000);
            } catch (InterruptedException e) {
                e.printStackTrace();
            }
            System.out.println("Thread" + " " + i);
        }
    }
}

Answer 1

测试它：让你的代码通过

告诉你它正在调用哪个线程

通过Thread.currentThread()
然后通过getId()和getName()

public class ThreadTest {
    public static void main(String[] args) {
        Thread currentThread = Thread.currentThread();
        System.out.printf("Main, Which Thread: %s, %d%n", 
                currentThread.getName(), 
                currentThread.getId());

        Abc abc = new Abc();
        abc.start();
    }
}

class Abc extends Thread {
    @Override
    public synchronized void start() {
        super.start();

        Thread currentThread = Thread.currentThread();
        System.out.printf("Start, Which Thread: %s, %d%n", 
                currentThread.getName(), 
                currentThread.getId());

        for (int i = 0; i < 10; i++) {
            try {
                Thread.sleep(1000);
            } catch (InterruptedException e) {
                e.printStackTrace();
            }
            System.out.println("Thread" + " " + i);
        }
    }

    @Override
    public void run() {
        super.run();

        Thread currentThread = Thread.currentThread();
        System.out.printf("Run, Which Thread: %s, %d%n", 
                currentThread.getName(), 
                currentThread.getId());
    }
}

对我来说，这会返回：

Main, Which Thread: main, 1
Start, Which Thread: main, 1
Run, Which Thread: Thread-0, 9
Thread 0
Thread 1
Thread 2
Thread 3
....

这证明你的Abc的start方法（正如预期的那样）在与调用代码相同的线程中调用而不是在新线程中调用，并且只有run()方法中的代码在新的内部被调用线。如上所述，您几乎从不需要或想要扩展Thread，而是实现Runnable或Callable。

如果我们在start方法而不是run方法中执行整个Thread功能会发生什么？

1 个答案: