IDE是Eclipse,語言是JAVA,Release下執行, a的結果是5,確定是有至run()函式中執行,可是在Debug模式下, 卻無法跳至run()函式中,似乎 跟mthread.join();這行有關, 請問有人知道為什麼嗎? public class mythread implements Runnable{ public static int a = 0; public void run() { for (int k = 0; k < 5; k++) { a = a + 1; } } public static void main(String[] args) throws Exception { Runnable r = new mythread(); Thread mthread = new Thread(r); mthread.start(); mthread.join(); System.out.println(a); } }