Thread: Variable question from a beginner

Hello all, this is my first post and thanks for any and all replies. I am teaching myself Java from books/tutorials and videos on the internet. I have a fundamental question; In the following code, is it possible to declare the variables (canvasWidth & canvasHeight)
at the beginning, so as to declare them just one time. All this program does is print a target in the center of the screen. I have commented out where I attempted to do this, but the sub-methods (?) did not recognize the variables. I realize this is Java 101, but I am very new to Java and still trying to understand the basics. Once again, thanks for all replies.

/*
* File: Target.java
* Name: 
* Section Leader: 
* -----------------
* This file is the starter file for the Target problem.
*/
 
import acm.graphics.*;
import acm.program.*;
import java.awt.*;
import acm.graphics.GCanvas.*;
//	This program places a target in the center of the screen.
 
public class Target extends GraphicsProgram {	
 
public void run() {
//	 double canvasWidth = getWidth();
//	 double canvasHeight = getHeight();
//	 System.out.println ("width: "+canvasWidth+" Height: "+canvasHeight);
outerRing();
midRing();
bullsEye();
}
 
//Places outer ring of target
 
public void outerRing() {
double canvasWidth = getWidth();
double canvasHeight = getHeight();
GOval outerRing = new GOval((canvasWidth/2-36), (canvasHeight/2-36), 72, 72);
outerRing.setColor (Color.red);
outerRing.setFillColor(Color.red);
outerRing.setFilled(true);
GRectangle bounds = outerRing.getBounds();
//	 println ("outerRing bounds: " + bounds);
add (outerRing);	
}
 
//Places next ring of target	
 
public void midRing() {
double canvasWidth = getWidth();
double canvasHeight = getHeight();
GOval midRing = new GOval((canvasWidth/2)-(36*.65), (canvasHeight/2-(36*.65)), 72*.65, 72*.65);
midRing.setColor (Color.white);
midRing.setFillColor(Color.white);
midRing.setFilled(true);
add (midRing);	
}
 
// Places bullseye on target	
 
public void bullsEye() {
double canvasWidth = getWidth();
double canvasHeight = getHeight();
GOval bullsEye = new GOval((canvasWidth/2)-(36*.3), (canvasHeight/2-(36*.3)), 72*.3, 72*.3);
bullsEye.setColor (Color.red);
bullsEye.setFillColor(Color.red);
bullsEye.setFilled(true);
add (bullsEye);
}
}

When I declare them under class, as shown below, the target is placed in the upper left hand corner.

/*
 * File: Target.java
 * Name: 
 * Section Leader: 
 * -----------------
 * This file is the starter file for the Target problem.
 */
 
import acm.graphics.*;
import acm.program.*;
import java.awt.*;
import acm.graphics.GCanvas.*;
//	This program places a target in the center of the screen.
 
public class Target extends GraphicsProgram {	
 
	double canvasWidth = getWidth();
	double canvasHeight = getHeight();
 
	public void run() {
//		double canvasWidth = getWidth();
//		double canvasHeight = getHeight();
//		System.out.println ("width: "+canvasWidth+" Height: "+canvasHeight);
		outerRing();
		midRing();
		bullsEye();
	}
 
//Places outer ring of target
 
	public void outerRing() {
//		double canvasWidth = getWidth();
//		double canvasHeight = getHeight();
		GOval outerRing = new GOval((canvasWidth/2-36), (canvasHeight/2-36), 72, 72);
		outerRing.setColor (Color.red);
		outerRing.setFillColor(Color.red);
		outerRing.setFilled(true);
		GRectangle bounds = outerRing.getBounds();
//		println ("outerRing bounds: " + bounds);
		add (outerRing);		
	}
 
//Places next ring of target	
 
	public void midRing() {
//		double canvasWidth = getWidth();
//		double canvasHeight = getHeight();
		GOval midRing = new GOval((canvasWidth/2)-(36*.65), (canvasHeight/2-(36*.65)), 72*.65, 72*.65);
		midRing.setColor (Color.white);
		midRing.setFillColor(Color.white);
		midRing.setFilled(true);
		add (midRing);	
	}
 
// Places bullseye on target	
 
	public void bullsEye() {
//		double canvasWidth = getWidth();
//		double canvasHeight = getHeight();
		GOval bullsEye = new GOval((canvasWidth/2)-(36*.3), (canvasHeight/2-(36*.3)), 72*.3, 72*.3);
		bullsEye.setColor (Color.red);
		bullsEye.setFillColor(Color.red);
		bullsEye.setFilled(true);
		add (bullsEye);
	}
}

I have commented out the original placement of the declarations.