java - Output for this test class is very confusing.Can anyone please explain the output?

Question

public class Test { 
    public static void main(String[] args) {        
        String msg= "Hello";
        print(msg);
        msg += "world";
        print(msg);
    }

    static void print(String msg) {
        System.out.println(msg);
        msg += "tttt";
        System.out.println(msg);        
    }
}

OutPut:

Hello Hellotttt Helloworld Helloworldtttt

Why the out has Helloworld after Hellotttt and not Hellottttworld?

Answer 1

Because in method static void print(String msg) , the change in msg will only be available in this method. After the execution of print(msg) for the first time, value of msg will be "Hello" again.

If you want output like Hello Hellotttt Hellottttworld Hellottttworldtttt

you can do it like this :

static void main(String[] args) {   
    String msg= "Hello";
    msg = print(msg);
    msg += "world";
    print(msg);

}

static String print(String msg) {
    System.out.println(msg);
    msg += "tttt";
    System.out.println(msg);
    return msg;
}