Question

I’ve got my code functioning and repeatedly changing the colors of the squares in my code, but all the squares are the same colors when the change.

Main program:

import java.awt.Graphics;
import java.awt.Color;
import java.awt.Font;
import java.util.Random;
import javax.swing.Timer;
import java.awt.event.ActionListener;
import java.awt.event.ActionEvent;
import java.awt.Canvas;
import javax.swing.JPanel;

public class RandomColoredBoxes extends JPanel
{
private Timer timer;
private final static int SLEEP = 110;

public RandomColoredBoxes()
{       
    setBackground(Color.BLACK);
    setVisible(true);

    ActionListener paintCaller = new ActionListener(){
        public void actionPerformed(ActionEvent event)
        {
            repaint();  
        }
    };
    timer = new Timer(SLEEP, paintCaller);
    timer.start();
}   

public void paintComponent( Graphics window )
{
    super.paintComponent(window);

    window.setColor(Color.RED);
    window.setFont(new Font("TAHOMA",Font.BOLD,12));
    window.drawString("Graphics Lab Lab11k ", 20, 40);
    window.drawString("Drawing boxes with nested loops ", 20, 80);

    drawBoxes(window);
}

public void drawBoxes(Graphics window)
{
    int colorValue1 = (int)(Math.random() * 256);
    int colorValue2 = (int)(Math.random() * 256);
    int colorValue3 = (int)(Math.random() * 256);

    Color random = new Color(colorValue1, colorValue2, colorValue3);
    window.setColor(random);
    //for loop to to across the x - getWidth() might be useful
    for(int x = 30; x <= getWidth()- 30; x+=15){
        for(int y = 100; y <= getHeight() - 30; y+= 15){
            window.fillRect(x, y, 8, 8);
        }
    }
        //for loop to go down the y - getHeight() might be useful

            //draw random colored boxes
}
}

And my graphics runner class:

import javax.swing.JFrame;

public class GraphicsRunnerRandom extends JFrame
{
private static final int WIDTH = 800;
private static final int HEIGHT = 600;

public GraphicsRunnerRandom()
{
    super("Graphics Runner");
    setSize(WIDTH,HEIGHT);

    getContentPane().add(new RandomColoredBoxes());                 

    //getContentPane().add(new RandomColoredBoxes());

    setVisible(true);
}

public static void main( String args[] )
{
    GraphicsRunnerRandom run = new GraphicsRunnerRandom();
}
}

other than the squares changing all-together, everything else is functioning as it should

Answer 1

Instead of this:

int colorValue1 = (int)(Math.random() * 256);
int colorValue2 = (int)(Math.random() * 256);
int colorValue3 = (int)(Math.random() * 256);

Color random = new Color(colorValue1, colorValue2, colorValue3);
window.setColor(random);
//for loop to to across the x - getWidth() might be useful
for(int x = 30; x <= getWidth()- 30; x+=15){
    for(int y = 100; y <= getHeight() - 30; y+= 15){
        window.fillRect(x, y, 8, 8);
    }
}

Try this:

//for loop to to across the x - getWidth() might be useful
for(int x = 30; x <= getWidth()- 30; x+=15){
    for(int y = 100; y <= getHeight() - 30; y+= 15){
        int colorValue1 = (int)(Math.random() * 256);
        int colorValue2 = (int)(Math.random() * 256);
        int colorValue3 = (int)(Math.random() * 256);

        Color random = new Color(colorValue1, colorValue2, colorValue3);
        window.setColor(random);

        window.fillRect(x, y, 8, 8);
    }
}

The basic difference is creating the new color (and calling window.setColor as well) from inside the loop- that way each time the loop starts, before drawing in the box, a new random color will be used.