running java main class using subprocess.Popen in python

Question

I want to execute java main class main.java by python using subprocess.Popen(). main.java takes 3 args.

I wonder how to do it? For example I have a HelloWorld.java class:

public class HelloWorld {
    public static void main(String[] args) {
        System.out.println("Hello World!" + args[0]);
    } }

I tried to call it in python using the command:

print (subprocess.Popen('java C:/Users/testing/Hello.Main sayHello', shell=True, stdout=subprocess.PIPE).stdout.read())

where 'sayHello' is the string args I want to pass in. It said

Error: Could not find or load main class C:.Users.testing.Hello.Main

Thanks

Answer 1

You may run your java file with extension .class the following way:

java your.path.Main arg1 arg2

where,

• java - command, which runs the Java interpreter
• your.path.Main - full name of your class (without .class)
• arg1 arg2 - the arguments (written by spaces or between ")

Further, when you formatted this line, it transmits in subprocess.Popen() as argument.

subprocess.Popen('java your.path.Main arg1 arg2')

I'm not Python programmer, because I advice you to read documentation about this method.