How do I use mouselistener and press event to change a filled square to another color? - swing

Question

This is for homework, I have most of this done but I am stuck on the final step (implementing a mouse event that will change one of my randomized colored squares to become red instead of it's assigned colors) and am concerned that using the methods provided by my prof are not suitable to this, as he has us repaint after mouse event (which I feel my code will just override with more random colors). Any assistance or nudge in the right direction would be helpful, and I am sure this is a mess.
Update as per Camickr's assistance, my code has changed to the following:
import java.awt.GridLayout;
import java.awt.Color;
import java.awt.Dimension;
import java.awt.Graphics;
import java.util.Random;
import javax.swing.*;
// MouseListener Imports
import java.awt.event.MouseListener;
import java.awt.event.MouseEvent;
public class Test extends JPanel implements MouseListener
{
static Color[][] framework = new Color[8][8];
static int redCounter = 0;
// main Creates a JFrame and instantiates the 2d array of color objects
public static void main(String[] args)
{
// The frame handles all the outside window work
JFrame frame = new JFrame("MouseListener demo");
// Allows the 'X' in the upper right to cause the program to exit
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
//Create and set up the content pane.
// contentPane holds a panel
JComponent newContentPane = new Test();
// MouseListenerDemo isa JPanel isa JComponent
newContentPane.setOpaque(true); //content panes must be opaque
frame.setContentPane(newContentPane);
//Display the window.
frame.pack();
/* Causes this Window to be sized to fit the preferred size and layouts of its subcomponents.
The resulting width and height of the window are automatically enlarged if either of dimensions
is less than the minimum size as specified by the previous call to the setMinimumSize method.
If the window and/or its owner are not displayable yet, both of them are made displayable before
calculating the preferred size. The Window is validated after its size is being calculated.
*/
frame.setVisible(true);
for (int x = 0; x < framework.length; x++) {
for (int y = 0; y < framework.length; y++) {
Color rc = randomColor();
framework[x][y] = rc;
}
}
}
// Constructor
public Test()
{
// layout the panel with an area in which to draw
super(new GridLayout(0,1));
// get Graphics object, which allows you to draw on the panel
// set initial size of the panel
setPreferredSize(new Dimension(400, 500));
// ADD this JPanel to the list of components notified when a mouse event happens
this.addMouseListener(this);
// calls paint()
repaint();
}
// draws the screen
public void paint(Graphics g)
{
// Get the size
Dimension d = this.getSize();
int size = 50; // The edge length of the squares
int xSt = 50; // Starting x-coordinate
int ySt = 50; // Starting y-coordinate
int n = 8; // n X n board
int xPos, yPos;
for(int row = 0; row < framework.length; row ++){
for (int col = 0; col < framework.length; col ++){
xPos = xSt*col;
yPos = xSt*row;
// set color
g.setColor (framework[row][col]);
// Draw square
g.fillRect(xPos, yPos, size, size);
}
}
g.setColor(Color.black);
g.drawString("There are " + redCounter + " reds." , d.width/3, d.height);
}
public static Color randomColor(){
Random rg = new Random();
int result = rg.nextInt(12);
Color color;
switch(result){
case 0: color = Color.black;
break;
case 1: color = Color.blue;
break;
case 2: color = Color.cyan;
break;
case 3: color = Color.darkGray;
break;
case 4: color = Color.yellow;
break;
case 5: color = Color.green;
break;
case 6: color = Color.lightGray;
break;
case 7: color = Color.magenta;
break;
case 8: color = Color.orange;
break;
case 9: color = Color.pink;
break;
case 10: color = Color.red; redCounter = redCounter + 1;
break;
case 11: color = Color.white;
break;
default: color = Color.black;
break;
}
return color;
}
// MouseListener methods
public void mousePressed(MouseEvent evt)
{
// demonstrates how to use the parameter
// to get the position of the mouse press
Dimension d = this.getSize();
int x = evt.getX();
int y = evt.getY();
System.out.println(x+","+y);//these co-ords are relative to the component
System.out.println(evt.getSource());
for (int i = 0; i < framework.length; i++) {
for (int j = 0; j < framework.length; j++) {
System.out.println(framework[i][j]);
if (evt.getSource().equals(framework[i][j])) {
framework[i][j] = Color.red;
redCounter = redCounter + 1;
}
}
}
repaint(); // redisplay the frame by eventually calling the paint() method
}
// do nothing for the other mouse actions
public void mouseReleased(MouseEvent evt) {}
public void mouseClicked(MouseEvent evt) {}
public void mouseEntered(MouseEvent evt) {}
public void mouseExited(MouseEvent evt) {}
}

Answer 1

am concerned that using the methods provided by my prof are not suitable to this, as he has us repaint after mouse event (which I feel my code will just override with more random colors).
The repaint() in the MouseEvent is correct. However more random colors will be generated because your painting code is incorrect.
A painting method should only paint the state of your component, not change the state. Therefore:
You need to keep a data structure (lets say a 2D array) to hold the Color of each cell. In the constructor of your class you would then iterate through this array and assign the random colors to each entry in the array.
Then in the painting method you just iterate through the array and paint each cell using the color from the array.
Note you should be overriding paintComponent(), not paint() for the custom painting.
Then in your MouseListener code you just reset the Color in the Array for the cell that was clicked and invoke repaint().

Answer 2

I fixed it by getting the position of x/y and dividing them by 50 (my square height/width) and putting the int into the array index.
public void mousePressed(MouseEvent evt)
{
// demonstrates how to use the parameter
// to get the position of the mouse press
Dimension d = this.getSize();
int x = evt.getX()/50;
int y = evt.getY()/50;
framework[y][x] = Color.red;
redCounter = redCounter+1;
repaint(); // redisplay the frame by eventually calling the paint() method
}