java - 处理 IllegalThreadStateException

Question

import java.io.*;
class Sysexecute
{
    public static void main(String args[]) throws IOException,InterruptedException,IllegalThreadStateException
    {
        Runtime rt= Runtime.getRuntime();
        Process p=rt.exec("ls");
        System.out.println(p.exitValue());
    }
}

我正在学习如何在 java 中执行系统命令，但出现了这个错误。我尝试使用 throws 来否定它，但没有用。请说明原因及解决方法

actual error:-
Exception in thread "main" java.lang.IllegalThreadStateException: process hasn't exited
    at java.lang.UNIXProcess.exitValue(UNIXProcess.java:270)
    at Sysexecute.main(Sysexecute.java:8)

Answer 1

调用 Process#waitFor()在尝试获取退出值之前。这会阻塞当前线程，直到生成的进程终止。如果你不这样做，Process#exitValue()抛出

IllegalThreadStateException - if the subprocess represented by this Process object has not yet terminated