java - 同一个线程看起来好像运行了两次，但在 Java 中只调用了一次

Question

我的main下有以下代码:

System.out.println(Thread.currentThread().getId());  
for(inti=0;i!=Lock.totalThreads;i++) {  
    System.out.println("thread wascreated");   
    (new Thread(new MyThread())).start();   
}
System.out.println("main finished running files");

MyThread 类如下所示:

public class MyThread implements Runnable {
    private static int threadCounter=0;
    private int myThreadId=0;
    @Override
    public void run() {
        synchronized(Lock.lock){
            threadCounter++;
            myThreadId=threadCounter;
        }
        System.out.println("run()");
        try {
            runMe();
        } catch (IOException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        } catch (InterruptedException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
    }

    private void runMe() throws IOException, InterruptedException {
        String currentFile;
        BufferedReader in;
        System.out.println("run()");
        switch(myThreadId){
        case 1:
            System.out.println("thread1 started");
            System.out.println("thread1 finished");
            System.out.println(Thread.currentThread().getId());
        case 2: 
            System.out.println("thread2 started");
            System.out.println("thread2 finished");
            System.out.println(Thread.currentThread().getId());

        }
    }

Lock 类如下所示:

public class Lock {
    public static final Lock lock=new Lock();
    public static final int totalThreads=1;
}

控制台输出是这样的:

1
thread was created
main finished running files
run()
runMe()
thread1 started
thread1 finished
8
thread2 started
thread2 finished
8

我很难理解为什么会发生这样的事情。
很明显(至少对我而言)只有一次线程被创建(只有一次我们可以看到 run()、runMe() 和 thread 是已创建)，但两次thread started/finished 和输出中的Thread ID。
为什么 threadCounter 递增两次，而只进入 run() 一次？

附言，我使用的是 Java 6。

Answer 1

case 1 和 case 2 之后都缺少 break;。