Wanting to change from a single object to an array.

[david522]

I had a singular object which referred to a class named "Ball"
I had it like this originally (I will only show the relevant code)

public class A3JPanel extends JPanel implements KeyListener, ActionListener {
	private Ball m_ball = new Ball(125, 0, 10, 10);

I've been following some instructions and I now want to create several of these objects in an array manner. I've changed the following pieces of code

public class A3JPanel extends JPanel implements KeyListener, ActionListener {
	private Ball[] m_ball;

        public A3JPanel() {
		m_ball = new Ball[6];
		for (int i = 0; i < m_ball.length; i++) {
			m_ball[i] = new Ball(125, 0, 10, 10);
		}
	}

However I have some methods in the Ball.java file which now no longer execute correctly and I'm wondering what I have to do to amend this...

A3JPanel.java:107: cannot find symbol
symbol : method move()
location: class Ball[]
m_ball.move(); // Move the ball.

[DarrylBurke]

The variable m_ball refers to the array. An array doesn't have a method move().

Recommended reading: Arrays (The Java™ Tutorials > Learning the Java Language > Language Basics)

db

[david522]

In the class I created, I made my own move method which simply changes some int variables.

Thanks, I read over it. I know the basics of an array but can't figure this one out..

[Toll]

You're trying to move the array, not the balls within it.

[NatureFreshMilk]

Try m_ball[1].move()... This refers to a Ball object in the array, where m_ball just refers to an array and as DarrylBurke said: an array doenst have a method called move().

so recap:
m_ball refers to array -> doenst have method move()
m_ball[1] refers to the second Ball object in array of Balls -> should have method move()

Hope this is correct and helps you!!

Peace!

[david522]

Cheers nature! I'm trying to implement the balls appearing from random locations around the window but the use of Math.random doesn't seem possible due to a double being required. Have tried changing everything to double but the "fillOval" method doesn't seem to accept doubles...

[Dark]

You could use java.util.Random
Random (Java Platform SE 6)

Random generator = new Random();
int x = generator.nextInt(5);