在批处理文件中调用 java class 并将“main”方法的返回值存储在批处理变量中

Question

Is it possible to run a java class in a batch file with a main method inside, changing the return type of the method from "void" to another type, and get the return value in batch file?

I mean something similar to the following:

Java class:

public class Main{

    public static String main(String[] args) {
        public String returnValue;
        
        // code to execute...
        
        return returnValue;
    }
}

Batch file:

...
set RETURNVALUE = ""
//call "java com.test.Main" and store return value in RETURNVALUE variable
...

I need to make some checks in the java class, and then execute the subsequent instructions in batch file according to the result given by the java class.

Any help will be appreciated

Answer 1

You can end the main method with System.exit() instead of return:

public class Main{
    public static void main(String[] args) {
        int returnValue;

        // code to execute...
        returnValue = 123;
        
        System.exit(returnValue);
    }
}

Then in the script:

#!/bin/bash

java ./Main.java
RETURNVALUE=$?

echo "The return value was $RETURNVALUE"

which gives you:

$ ./script.sh  
The return value was 123

The exit code can't be a string, only a number from 0 to 255. If you want to return a string instead, consider printing to stdout instead and saving that to a variable.