public class TwoThread extends Thread {
    private Thread creatorThread;

    public TwoThread() {
        // make a note of the thread that constructed me!
        creatorThread =Thread.currentThread();
    }

    public void run() {
        for ( int i = 0; i < 10; i++ ) {
            printMsg();
        }
    }

    public void printMsg() {
        // get a reference to the thread running this
        Thread t = Thread.currentThread();

        if ( t == creatorThread ) {
            System.out.println("Creator thread");
        } else if ( t == this ) {
            System.out.println("New thread");
        } else {
            System.out.println("Mystery thread --unexpected!");
        }
    }

    public static void main(String[] args) {
        TwoThread tt = new TwoThread();
        tt.start();

        for ( int i = 0; i < 10; i++ ) {
            tt.printMsg();
        }
    }
}
程序中的creatorThread = Thread.currentThread();和Thread t = Thread.currentThread();是什么意思？？？