Swing/AWT/SWT :: Possible To Make Graphics Such As FillRect Into A Variable?

I want to do a simple background which is only rendered once onto my screen. I want to use

G.fillRect(0, 0, getWidth(), getHeight());

and make the whole background black, but only once. I wanted to try out making the fillRect into a variable so I can do:

if (background == null) { //background is the variables name.
G.fillRect(0, 0, getWidth(), getHeight());
}

The point is, I want G.fillRect(0, 0, getWidth(), getHeight()); to be a variable, even if this is the wrong way to approach what I want to accomplish, is it possible to make this line of code into one variable? The rest of my code if you need info:

package com.game.blobber;
import java.util.Random;
import java.awt.Canvas;
import java.awt.Dimension;
import java.awt.Graphics;
import java.awt.image.BufferStrategy;

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