how to pass value to paint method - graphics

Question

I am just at very beginnig in Java coding, so far I could solve my problems finding solutions on internet, but this time I just stucked.
I want to create a grid(pattern) of filled rectangles, and it works fine, but then I would like to change colour of rectangles on specific position, and this part is just not working. I have no idea why, what am I doing wrong ?
// **file : MainWindow.java **
import java.util.Scanner;
import javax.swing.JFrame;
import javafx.scene.paint.Color;
import javafx.scene.shape.Rectangle;
public class MainWindow {
JFrame frame = new JFrame();
int pos_X;
int pos_Y;
// constructor for frame
public MainWindow (String title) {
frame.setSize(1000, 1000);
frame.setTitle(title);
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
for (int i=0;i<26;i++){ // works fine
for (int j=0;j<26;j++){
Shape shape = new Shape (110+i*20,110+j*20,19,19,5,100,220); //(x,y, width,height, R-colour, G-colour, B-colour)
frame.add(shape);
frame.setVisible(true); }}
pos_X= 15;
pos_Y = 15;
Shape shape = new Shape (110+pos_X*20,110+pos_Y*20,19,19,250,0,20); // it doesn't work ???
frame.add(shape);
frame.setVisible(true);
}
public static void main(String[] args){
new MainWindow(" my window ");
}
}
// **file : Shape.java **
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.Rectangle;
import java.awt.Color;
import java.awt.Color.*;
import javax.swing.JComponent;
public class Shape extends JComponent{
int width, height, xcoord, ycoord, col_r, col_g,col_b;
//constructor
public Shape (int x, int y ,int w,int h, int k, int l, int m)
{
this.width = w;
this.height = h;
this.xcoord = x;
this.ycoord = y;
this.col_r = k;
this.col_g = l;
this.col_b = m;
}
public void paintComponent(Graphics g){
Graphics2D g2d = (Graphics2D) g;
Color x= new Color( col_r,col_g, col_b );
g.setColor(x);
g.fillRect(xcoord, ycoord, width, height);
}
}

Answer 1

If I understand right, what you want could be done ensuring the shape has drawn after the grid, so
pos_X= 15;
pos_Y = 15;
Shape shape = new Shape (110+pos_X*20,110+pos_Y*20,19,19,250,0,20); // it doesn't work ???
frame.setComponentZOrder(shape,0)
frame.add(shape);
frame.setVisible(true);
...
please note the
frame.setComponentZOrder(shape,0)
which ensure that the colored shape is drawn above the others.
In alternative your
P.S.
if it doesn't work try frame.setComponentZOrder(shape,frame.getComponentCount())
See also here for an alternative