How can i return a value from a void method in java

Question

Ok so i have this code and obviously the "g = gd" from the render method isnt modifying the field value of "g".

How can i make it so that the render method modifies the field g?

I want to have a graphics field so i can use graphics to print strings outside the render method but i really have no idea how to do that.

private Graphics g;

private BufferedImage background;

public Tutorial(Core core){
    background = core.getResources().getImage(4);
}

public void render(Graphics gd) {
    g = gd;
    g.drawImage(background, 0, 0, null);
}

EDIT:

ok this is the whole class how can i modify it so that the displayMessage will work ? tick() is called before render() , that might be a problem?

package com.andrewxd.spaceinvaders.levels;

import java.awt.Color;
import java.awt.Font;
import java.awt.Graphics;
import java.awt.image.BufferedImage;

import com.andrewxd.spaceinvaders.main.Core;

public class Tutorial implements Levels{

    private Graphics g;

    private BufferedImage background;

    public Tutorial(Core core){
        background = core.getResources().getImage(4);
    }

    public void render(Graphics gd) {
        g = gd;
        g.drawImage(background, 0, 0, null);
    }

    public void tick() {
        displayMessage("Welcome", 200,200);
    }

    public void displayMessage(String message, int x, int y) {
        g.setFont(new Font("ARIAL", Font.BOLD, 20));
        g.setColor(Color.RED);
        g.drawString(message, x, y);
    }

    public void displayMessage(String message, int x, int y, Font font) {
        g.setFont(font);
        g.setColor(Color.WHITE);
        g.drawString(message, x, y);
    }

    public void displayMessage(String message, int x, int y, Font font, Color color) {
        g.setFont(font);
        g.setColor(color);
        g.drawString(message, x, y);
    }

}

Answer 1

• You can't return a value from a void method, that's the purpose of void method, it does what it does and finish.

• Java is pass-by-value, when you pass a reference type, its address won't be changed but its attributes will be effected by the change.

Answer 2

You could try to get the object from a factory class, which you want to modify... But it is not possible to use return ; in a void method...

You should use google and find best practises and patterns for this case ;-)

Answer 3

return if used other than void type, but you can change global variable's data. that way you can achieve it, or else use some other data type...

Answer 4

"void" is used when you don't want your method to return a value.

If you want it to return something then isntead of "void", Put the type you want to return. For example:

public Graphics returnG(){
 Graphics g = new Graphics();
return    g;

}

this would return a Graphics Object named g.

But again, it is not possible for a void method to return something.