Java GUI Rectangle Graphics

Question 1

Can anyone explain the proper way to draw graphics on a frame? Ive looked at other examples and this should work but it doesnt. See the "Paint" method. I tried to draw a square (rectangle) and it doesnt appear on my frame.

Regards

import java.awt.Color;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.Rectangle;
import javax.swing.event.ChangeEvent;
import javax.swing.event.ChangeListener;
public class Colors extends javax.swing.JFrame {
 public Colors() {
 initComponents();
 addSliderListeners();
 addSliderLabels();
 }
 public void Paint(Graphics g){
 Graphics2D g2 = (Graphics2D)g;
 g2.setColor(Color.BLUE);
 g2.draw(new Rectangle(25,25,200,200));
 }
 private void addSliderListeners(){
 sliderRed.addChangeListener(new ChangeListener() {
 public void stateChanged(ChangeEvent e) {
 updateImage();
 }
 });
 sliderGreen.addChangeListener(new ChangeListener() {
 public void stateChanged(ChangeEvent e) {
 updateImage();
 }
 });
 sliderBlue.addChangeListener(new ChangeListener() {
 public void stateChanged(ChangeEvent e) {
 updateImage();
 }
 });
 }
 private void updateImage(){
 lblRedDec.setText(""+sliderRed.getValue());
 lblRedDec.setForeground(new Color(sliderRed.getValue(),0,0));
 lblRedHex.setText(Integer.toHexString(sliderRed.getValue()));
 lblRedHex.setForeground(lblRedDec.getForeground());
//Color textColor = new Color( 255-lblRedDec.getForeground().getRed(),
// 255-lblRedDec.getForeground().getGreen(),
// 255-lblRedDec.getForeground().getBlue()
// );
//jLabel1.setBackground(textColor);
 lblGreenDec.setText(""+sliderGreen.getValue());
 lblGreenDec.setForeground(new Color(0,sliderGreen.getValue(),0));
 lblGreenHex.setText(Integer.toHexString(sliderGreen.getValue()));
 lblGreenHex.setForeground(lblGreenDec.getForeground());
 lblBlueDec.setText(""+sliderBlue.getValue());
 lblBlueHex.setText(Integer.toHexString(sliderBlue.getValue()));
 lblBlueDec.setForeground(new Color(0,0,sliderBlue.getValue()));
 lblBlueHex.setForeground(lblBlueDec.getForeground());
 }
 private void addSliderLabels() {
 sliderRed.setPaintLabels(true);
 sliderGreen.setPaintLabels(true);
 sliderBlue.setPaintLabels(true);
 }
/**
 * This method is called from within the constructor to initialize the form.
 * WARNING: Do NOT modify this code. The content of this method is always
 * regenerated by the Form Editor.
 */
 @SuppressWarnings("unchecked")
 // <editor-fold defaultstate="collapsed" desc="Generated Code">
 private void initComponents() {
 sliderRed = new javax.swing.JSlider();
 lblRed = new javax.swing.JLabel();
 lblRedHex = new javax.swing.JLabel();
 lblRedDec = new javax.swing.JLabel();
 sliderGreen = new javax.swing.JSlider();
 lblGreen = new javax.swing.JLabel();
 lblGreenHex = new javax.swing.JLabel();
 lblGreenDec = new javax.swing.JLabel();
 sliderBlue = new javax.swing.JSlider();
 lblBlue = new javax.swing.JLabel();
 lblBlueHex = new javax.swing.JLabel();
 lblBlueDec = new javax.swing.JLabel();
 setDefaultCloseOperation(javax.swing.WindowConstants.EXIT_ON_CLOSE);
 setResizable(false);
 sliderRed.setMajorTickSpacing(15);
 sliderRed.setMaximum(255);
 sliderRed.setMinorTickSpacing(5);
 sliderRed.setOrientation(javax.swing.JSlider.VERTICAL);
 sliderRed.setPaintTicks(true);
 sliderRed.setSnapToTicks(true);
 sliderRed.setToolTipText("");
 sliderRed.setValue(212);
 sliderRed.setCursor(new java.awt.Cursor(java.awt.Cursor.DEFAULT_CURSOR));
 sliderRed.setName(""); // NOI18N
 lblRed.setText("Red");
 lblRedHex.setText("hex");
 lblRedDec.setText("dec");
 sliderGreen.setMajorTickSpacing(15);
 sliderGreen.setMaximum(255);
 sliderGreen.setMinorTickSpacing(5);
 sliderGreen.setOrientation(javax.swing.JSlider.VERTICAL);
 sliderGreen.setPaintTicks(true);
 sliderGreen.setSnapToTicks(true);
 sliderGreen.setToolTipText("");
 sliderGreen.setValue(35);
 sliderGreen.setCursor(new java.awt.Cursor(java.awt.Cursor.DEFAULT_CURSOR));
 sliderGreen.setName(""); // NOI18N
 lblGreen.setText("Green");
 lblGreenHex.setText("hex");
 lblGreenDec.setText("dec");
 sliderBlue.setMajorTickSpacing(15);
 sliderBlue.setMaximum(255);
 sliderBlue.setMinorTickSpacing(5);
 sliderBlue.setOrientation(javax.swing.JSlider.VERTICAL);
 sliderBlue.setPaintTicks(true);
 sliderBlue.setSnapToTicks(true);
 sliderBlue.setToolTipText("");
 sliderBlue.setValue(218);
 sliderBlue.setCursor(new java.awt.Cursor(java.awt.Cursor.DEFAULT_CURSOR));
 sliderBlue.setName(""); // NOI18N
 lblBlue.setText("Blue");
 lblBlueHex.setText("hex");
 lblBlueDec.setText("dec");
 javax.swing.GroupLayout layout = new javax.swing.GroupLayout(getContentPane());
 getContentPane().setLayout(layout);
 layout.setHorizontalGroup(
 layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
 .addGroup(javax.swing.GroupLayout.Alignment.TRAILING, layout.createSequentialGroup()
 .addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.TRAILING)
 .addGroup(layout.createSequentialGroup()
 .addContainerGap(javax.swing.GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE)
 .addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
 .addComponent(lblRedHex)
 .addComponent(lblRed)
 .addComponent(lblRedDec))
 .addGap(25, 25, 25))
 .addGroup(layout.createSequentialGroup()
 .addGap(26, 279, Short.MAX_VALUE)
 .addComponent(sliderRed, javax.swing.GroupLayout.PREFERRED_SIZE, 71, javax.swing.GroupLayout.PREFERRED_SIZE)))
 .addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED)
 .addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
 .addComponent(sliderGreen, javax.swing.GroupLayout.Alignment.TRAILING, javax.swing.GroupLayout.PREFERRED_SIZE, 71, javax.swing.GroupLayout.PREFERRED_SIZE)
 .addGroup(javax.swing.GroupLayout.Alignment.TRAILING, layout.createSequentialGroup()
 .addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
 .addComponent(lblGreenHex)
 .addComponent(lblGreen)
 .addComponent(lblGreenDec))
 .addGap(25, 25, 25)))
 .addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.UNRELATED)
 .addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
 .addComponent(sliderBlue, javax.swing.GroupLayout.Alignment.TRAILING, javax.swing.GroupLayout.PREFERRED_SIZE, 71, javax.swing.GroupLayout.PREFERRED_SIZE)
 .addGroup(javax.swing.GroupLayout.Alignment.TRAILING, layout.createSequentialGroup()
 .addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
 .addComponent(lblBlueHex)
 .addComponent(lblBlue)
 .addComponent(lblBlueDec))
 .addGap(25, 25, 25)))
 .addGap(6, 6, 6))
 );
 layout.setVerticalGroup(
 layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
 .addGroup(javax.swing.GroupLayout.Alignment.TRAILING, layout.createSequentialGroup()
 .addContainerGap(javax.swing.GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE)
 .addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.TRAILING)
 .addGroup(layout.createSequentialGroup()
 .addComponent(lblBlueDec)
 .addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED)
 .addComponent(lblBlueHex)
 .addGap(18, 18, 18)
 .addComponent(lblBlue)
 .addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED)
 .addComponent(sliderBlue, javax.swing.GroupLayout.PREFERRED_SIZE, 285, javax.swing.GroupLayout.PREFERRED_SIZE))
 .addGroup(layout.createSequentialGroup()
 .addComponent(lblGreenDec)
 .addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED)
 .addComponent(lblGreenHex)
 .addGap(18, 18, 18)
 .addComponent(lblGreen)
 .addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED)
 .addComponent(sliderGreen, javax.swing.GroupLayout.PREFERRED_SIZE, 285, javax.swing.GroupLayout.PREFERRED_SIZE))
 .addGroup(layout.createSequentialGroup()
 .addComponent(lblRedDec)
 .addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED)
 .addComponent(lblRedHex)
 .addGap(16, 16, 16)
 .addComponent(lblRed)
 .addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED)
 .addComponent(sliderRed, javax.swing.GroupLayout.PREFERRED_SIZE, 285, javax.swing.GroupLayout.PREFERRED_SIZE)))
 .addContainerGap())
 );
 pack();
 }// </editor-fold>
 public static void main(String args[]) {
 /* Set the Nimbus look and feel */
 //<editor-fold defaultstate="collapsed" desc=" Look and feel setting code (optional) ">
 /* If Nimbus (introduced in Java SE 6) is not available, stay with the default look and feel.
 * For details see http://download.oracle.com/javase/tutorial/uiswing/lookandfeel/plaf.html 
 */
 try {
 for (javax.swing.UIManager.LookAndFeelInfo info : javax.swing.UIManager.getInstalledLookAndFeels()) {
 if ("Nimbus".equals(info.getName())) {
 javax.swing.UIManager.setLookAndFeel(info.getClassName());
 break;
 }
 }
 } catch (ClassNotFoundException ex) {
 java.util.logging.Logger.getLogger(Colors.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
 } catch (InstantiationException ex) {
 java.util.logging.Logger.getLogger(Colors.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
 } catch (IllegalAccessException ex) {
 java.util.logging.Logger.getLogger(Colors.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
 } catch (javax.swing.UnsupportedLookAndFeelException ex) {
 java.util.logging.Logger.getLogger(Colors.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
 }
 //</editor-fold>
 /* Create and display the form */
 java.awt.EventQueue.invokeLater(new Runnable() {
 public void run() {
 new Colors().setVisible(true);
 }
 });
 }
 // Variables declaration - do not modify
 private javax.swing.JLabel lblBlue;
 private javax.swing.JLabel lblBlueDec;
 private javax.swing.JLabel lblBlueHex;
 private javax.swing.JLabel lblGreen;
 private javax.swing.JLabel lblGreenDec;
 private javax.swing.JLabel lblGreenHex;
 private javax.swing.JLabel lblRed;
 private javax.swing.JLabel lblRedDec;
 private javax.swing.JLabel lblRedHex;
 private javax.swing.JSlider sliderBlue;
 private javax.swing.JSlider sliderGreen;
 private javax.swing.JSlider sliderRed;
 // End of variables declaration
}

Question 2

Change public void Paint(Graphics g) to public void paint(Graphics g) and also add annotation @Override before this method

Question 3

As general advice. Don't paint to a top-level container like JFrame. Instead @Override paintComponent(Graphics)` in JPanel that is added to the frame, or alternnately, paint in a BufferedImage that is added to the frame (or a panel etc.).

Question 4

As general practice, you must call super.paint

Question 5

You might like to take the time to read through Graphics 2D, Performing Custom Painting and Painting in AWT and Swing

Question 6

@CAMOBAP: You provided the quickest correct solution and I will like to give you credit if you post it as an answer so I can select yours as the best answer.

Question 7

It's paint (with a lower case 'p')

Question 8

as CAMOBAB said in the comments

Change public void Paint(Graphics g) to public void paint(Graphics g) and also add annotation @Override before this method

Maurice Perry 32.9k9 gold badges72 silver badges97 bronze badges · Accepted Answer · 2012-11-16 09:38:27Z

1

It's paint (with a lower case 'p')

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answered Nov 16, 2012 at 9:38

Maurice Perry's user avatar

Maurice Perry

32.9k9 gold badges72 silver badges97 bronze badges

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