从另一个java程序运行java程序 [英] Running a java program from another java program

问题描述

我正在研究一个简单的java程序。它只是编译并执行另一个java程序。我正在使用Runtime.exec（）函数进行编译和运行。编译没有问题。但是当它运行时，如果第二个程序需要输入来从键盘读取，我不能从主进程中提供它。我使用了getOutputStream（）函数。但它无济于事。我将提供我的代码。

I am working on a simple java program. It simply compiles and executes another java program. I am using Runtime.exec() function to compile and run. There is no problem with compilation. but when it runs, if the second program needs an input to read from keyboard, I can't give it from the master process. I used getOutputStream() function. but it couldn't help. I will provide my code.

public class sam {  
    public static void main(String[] args) throws Exception {  
        try { 
             Process p = Runtime.getRuntime().exec("javac sam2.java");
             Process p2 = Runtime.getRuntime().exec("java sam2");
             BufferedReader in = new BufferedReader(  
                                new InputStreamReader(p2.getInputStream()));

             OutputStream out = p.getOutputStream();
             String line = null; 
             line = in.readLine();
             System.out.println(line);
             input=input+"\n";
             out.write(input.getBytes());
             p.wait(10000);
             out.flush();
        }catch (IOException e) {  
             e.printStackTrace();  
        }  
    }  
}  

这是我的主程序（ sam.java）。

This is my master program(sam.java).

以下是sam2.java的代码

The following is the code of sam2.java

public class sam2 {  
public static void main(String[] args) throws Exception {  

    BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
    String str; 
    System.out.println("Enter the number..\n");
    str = br.readLine(); 
    System.out.println(Integer.parseInt(str));

    }  
}  

没有问题，如果我的话第二个程序只有打印声明。但是当我不得不从另一个人那里读到东西时就会出现这个问题。

There is no problem, if my second program has only printing statements. But the problem arises when I have to read something from the other.

推荐答案

这有点奇怪但是你可以运行第二个程序没有分叉。只需调用其中的main方法即可。所以忘记运行时部分并执行以下操作：

It is a bit strange but you can run the second program without forking it. Just calling the main method in it. So forget the runtime section and do this:

sam2.main(new String[0]);

当然这样你必须在编译时编译sam2

Of course this way you must compile sam2 at compile time

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