php shell_exec executing java program [duplicate]

In PHP code I try to execute Java program using shell_exec but I get empty line.

When I tried to execute program in bash:

#bin/bash

echo "aaa"

I get "aaa" but when i tried to execute the same file with

#bin/bash

java MainApp

I got empty line

This is the java code

public class MainApp{
        public static void main(String[] args)
        {
                System.out.print(":]");
        }
}

When i do:

#bin/bash

echo "aaa"
java MainApp
echo "bbb"

I get "aaa bbb"

I wont to get ":]" string How to make it work?

Maybe printing line with System.out.println(String ) is not the same as echo and printing line is not the same as returning value