class HelloWorld {
    public static void main(String[] args) throws InterruptedException {
        Thread myThread = new Thread() {
            public void run(){
                System.out.println("Hello from new Thread!");
            }
        };
        
        myThread.start();
        Thread.yield();
        
        System.out.println("Hello from main Thread!");
        myThread.join();
    }
}

《七周七并发模型》
作者说结果可能是

结果可能一

Hello from main Thread!
Hello from new Thread!

结果可能二

Hello from new Thread!
Hello from main Thread!

为什么我的结果只有一。