多线程面试题一路，请写出输出结果

多线程面试题一道，请写出输出结果

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public class ThreadRun extends Thread{public static void main(String agrs[]) throws Exception {ThreadRun tr = new ThreadRun();System.out.print("b");tr.start();System.out.print("c");tr.join();System.out.print("d");}public void run() {System.out.print("a");}}

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