repaint() not invoking paintComponent()? - swing

Question

Hello I am trying to solve the following problem: Write a program that prompts the user to enter the x- and y-positions of a center point and a radius, using text fields. When the user clicks a "Draw" button, draw a circle with that center and radius in a component. I do not see what is wrong in my code but something is because it doesnt seem like repaint() is invoking paintComponent() as message will change to TESTING 1 but not TESTING 2 and no drawing is made.
My Code:
import java.util.*;
import javax.swing.*;
import java.awt.*;
import java.applet.*;
import java.awt.geom.*;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
public class q3{
public static class cgPanel extends JPanel{
private static double x;
private static double y;
private static double r;
private static JTextField xField;
private static JTextField yField;
private static JTextField rField;
private static JButton draw;
private static JLabel message;
//This is all just Layout work.
public cgPanel(){
setLayout(new BorderLayout());
JPanel drawPanel = new JPanel();
drawPanel.setBackground(Color.WHITE);
add(drawPanel, BorderLayout.CENTER);
message = new JLabel("");
JPanel sub1ForSub1 = new JPanel();
sub1ForSub1.add(message);
JLabel coordinates = new JLabel("Coordinates:");
JPanel sub2ForSub1 = new JPanel();
sub2ForSub1.add(coordinates);
JPanel subPanel1 = new JPanel();
subPanel1.setLayout(new GridLayout(2, 1));
subPanel1.add(sub1ForSub1);
subPanel1.add(sub2ForSub1);
JLabel xLabel = new JLabel("x:");
xField = new JTextField(4);
JLabel yLabel = new JLabel(" y:");
yField = new JTextField(4);
JLabel rLabel = new JLabel(" Radius:");
rField = new JTextField(4);
JPanel subPanel2 = new JPanel();
subPanel2.add(xLabel);
subPanel2.add(xField);
subPanel2.add(yLabel);
subPanel2.add(yField);
subPanel2.add(rLabel);
subPanel2.add(rField);
draw = new JButton("Draw");
ActionListener bL = new ButtonListener();
draw.addActionListener(bL);
JPanel subPanel3 = new JPanel();
subPanel3.add(draw);
JPanel Panel = new JPanel();
Panel.setLayout(new BorderLayout());
Panel.add(subPanel1, BorderLayout.NORTH);
Panel.add(subPanel2, BorderLayout.CENTER);
Panel.add(subPanel3, BorderLayout.SOUTH);
add(Panel, BorderLayout.SOUTH);
setVisible(true);
}
static class ButtonListener extends JComponent implements ActionListener{
public void actionPerformed(ActionEvent e){
try{
String xString = xField.getText();
String yString = yField.getText();
String rString = rField.getText();
message.setText("TESTING 1");
x = Double.parseDouble(xString);
y = Double.parseDouble(yString);
r = Double.parseDouble(rString);
repaint();
}
catch (NumberFormatException exception){
message.setText("Please enter a number.");
}
}
//This is where I cant seem to get the code in paintComponent to run when the Draw button is pressed.
public void paintComponent(Graphics g){
Graphics2D g2 = (Graphics2D) g;
Ellipse2D.Double circle = new Ellipse2D.Double(x - r, y - r, r*2, r*2);
g2.draw(circle);
message.setText("TESTING 2");
}
}
}
public static void main(String[] args){
JFrame frame = new JFrame();
frame.setSize(800, 800);
frame.setTitle("Circle Generator");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
cgPanel panel = new cgPanel();
frame.add(panel);
frame.setVisible(true);
}
}

Answer 1

So, a couple of things.
Your problem stems from that fact that your ButtonListener is extending a JComponent, so the repaint() method is calling the one for the ButtonListener (which really isn't a JComponent).
And the paintComponent method is also for the the ButtonListener.
Instead, you want your button listener to have access to your cgPanel, so it can tell IT to repaint. And your paintComponent needs to be moved to the cgPanel, but even then you probably don't want it there since you have a bunch of other components on cgPanel.
It's not clear from your code where you really want the circle to be drawn.
You should probably create a CirclePanel that extend JPanel, and overrides paintComponent to draw your circles, and then add that to your cgPanel. Then make your ButtonListener tell the CirclPanel instance to repaint.