Hello everyone, I'm new here, and reletively terrible at coding, so I was hoping I could get some assistance with a program I've been working on. My assignment is to create a Frame that allows the user to choose where to paint a circle using a horizontal and vertical scroll bar and choose the color using a ComboBox. I got to the point where it would paint the circle on the screen (albeit not in the correct location) and I cannot get the sliders to line up with my circle, nor can I get my ComboBox to choose different colors for the life of me. Can anyone take a look at my code and offer any help? I can post a picture of the interface I have created with the Swing components if anyone needs it for reference. I really hope someone can help me figure this out!

/*
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 * and open the template in the editor.
 */
package jfhomework2;

import java.awt.Color;
import java.awt.Graphics;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import javax.swing.JComboBox;

/**
 *
 * @author Josh
 */
public class Window extends javax.swing.JFrame implements ActionListener {

    String currentColor;

    /**
     * Creates new form Window
     */
    public Window(String color) {
        initComponents();
    }

    private Window() {
        throw new UnsupportedOperationException("Not yet implemented");
    }

    /**
     * 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() {

        jSlider1 = new javax.swing.JSlider();
        jSlider2 = new javax.swing.JSlider();
        button1 = new java.awt.Button();
        jComboBox1 = new javax.swing.JComboBox();
        jPanel1 = new javax.swing.JPanel();

        setDefaultCloseOperation(javax.swing.WindowConstants.EXIT_ON_CLOSE);

        jSlider1.setMaximum(530);
        jSlider1.setPaintTicks(true);
        jSlider1.setValue(0);

        jSlider2.setMaximum(354);
        jSlider2.setOrientation(javax.swing.JSlider.VERTICAL);
        jSlider2.setPaintTicks(true);
        jSlider2.setValue(0);

        button1.setLabel("Show");
        button1.addActionListener(new java.awt.event.ActionListener() {
            public void actionPerformed(java.awt.event.ActionEvent evt) {
                button1ActionPerformed(evt);
            }
        });

        jComboBox1.setModel(new javax.swing.DefaultComboBoxModel(new String[] { "Red", "Blue", "Yellow", "Green" }));
        jComboBox1.setName("jComboBox1"); // NOI18N
        jComboBox1.addMouseListener(new java.awt.event.MouseAdapter() {
            public void mouseClicked(java.awt.event.MouseEvent evt) {
                color(evt);
            }
        });
        jComboBox1.addActionListener(new java.awt.event.ActionListener() {
            public void actionPerformed(java.awt.event.ActionEvent evt) {
                jComboBox1ActionPerformed(evt);
            }
        });

        jPanel1.setMaximumSize(new java.awt.Dimension(500, 500));

        javax.swing.GroupLayout jPanel1Layout = new javax.swing.GroupLayout(jPanel1);
        jPanel1.setLayout(jPanel1Layout);
        jPanel1Layout.setHorizontalGroup(
            jPanel1Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
            .addGap(0, 530, Short.MAX_VALUE)
        );
        jPanel1Layout.setVerticalGroup(
            jPanel1Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
            .addGap(0, 354, Short.MAX_VALUE)
        );

        javax.swing.GroupLayout layout = new javax.swing.GroupLayout(getContentPane());
        getContentPane().setLayout(layout);
        layout.setHorizontalGroup(
            layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
            .addGroup(layout.createSequentialGroup()
                .addContainerGap()
                .addComponent(jSlider2, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE)
                .addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.UNRELATED)
                .addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
                    .addComponent(jSlider1, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE)
                    .addGroup(layout.createSequentialGroup()
                        .addComponent(jPanel1, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE)
                        .addGap(0, 0, Short.MAX_VALUE)))
                .addContainerGap())
            .addGroup(javax.swing.GroupLayout.Alignment.TRAILING, layout.createSequentialGroup()
                .addContainerGap(javax.swing.GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE)
                .addComponent(jComboBox1, javax.swing.GroupLayout.PREFERRED_SIZE, 118, javax.swing.GroupLayout.PREFERRED_SIZE)
                .addGap(31, 31, 31)
                .addComponent(button1, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE)
                .addGap(214, 214, 214))
        );
        layout.setVerticalGroup(
            layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
            .addGroup(layout.createSequentialGroup()
                .addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
                    .addGroup(layout.createSequentialGroup()
                        .addContainerGap()
                        .addComponent(jSlider2, javax.swing.GroupLayout.PREFERRED_SIZE, 369, javax.swing.GroupLayout.PREFERRED_SIZE))
                    .addGroup(layout.createSequentialGroup()
                        .addGap(19, 19, 19)
                        .addComponent(jPanel1, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE)))
                .addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.UNRELATED, javax.swing.GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE)
                .addComponent(jSlider1, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE)
                .addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED)
                .addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING, false)
                    .addComponent(button1, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE)
                    .addComponent(jComboBox1))
                .addGap(22, 22, 22))
        );

        pack();
    }// </editor-fold>

    private void button1ActionPerformed(java.awt.event.ActionEvent evt) {                                        
        paintComponent(this.getGraphics());
    }                                       

    private void color(java.awt.event.MouseEvent evt) {
    }

    private void jComboBox1ActionPerformed(java.awt.event.ActionEvent evt) {
        // TODO add your handling code here:
    }

    /**
     * @param args the command line arguments
     */
    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(Window.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
        } catch (InstantiationException ex) {
            java.util.logging.Logger.getLogger(Window.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
        } catch (IllegalAccessException ex) {
            java.util.logging.Logger.getLogger(Window.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
        } catch (javax.swing.UnsupportedLookAndFeelException ex) {
            java.util.logging.Logger.getLogger(Window.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 Window().setVisible(true);
            }
        });
    }

    public void paintComponent(Graphics g) {
        int circleX = jSlider1.getValue();
        int circleY = jSlider2.getMaximum() - jSlider2.getValue();
        super.paintComponents(g);
        g.fillOval(circleX, circleY, 30, 30);
        g.drawOval(circleX, circleY, 30, 30);
    }

    @Override
    public void actionPerformed(ActionEvent e) {
        JComboBox cb = (JComboBox) e.getSource();
        String colorName = (String) cb.getSelectedItem();
        Graphics g = jPanel1.getGraphics();
        if (colorName.equals("Red")) {
            g.setColor(Color.RED);
        }

        if (colorName.equals("Blue")) {
            g.setColor(Color.BLUE);
        }

        if (colorName.equals("Yellow")) {
            g.setColor(Color.YELLOW);
        }

        if (colorName.equals("Green")) {
            g.setColor(Color.GREEN);
        }

    }
    // Variables declaration - do not modify
    private java.awt.Button button1;
    private javax.swing.JComboBox jComboBox1;
    private javax.swing.JPanel jPanel1;
    private javax.swing.JSlider jSlider1;
    private javax.swing.JSlider jSlider2;
    // End of variables declaration
}

ehm .. no, we don't need to look at a picture of the JFrame, we though, however, need to know what exactly it is you need help with. is it the JSlider issue? the JCombobox issue? what have you tried, and what doesn't work?

I assume you have figured out the possibilities of the combination of the getSelectedItem method and some basic data validation?

Trying to get the Graphics and change it outside a paintComponent is always going to be dodgy. You don't know what else is doing anything to that Graphics (not to mention the double-buffering that swing does for you). Plus, it looks like you are getting the graphics for some component that isn't the one you paint on line 182 anyway.
The "proper" way is to have color variable, set that in the actionPerformed, use that in the paintComponent to set the Graphic's color. You'll need to call repaint() for your panel so Swing knows to update after you have changed the color variable.

This article has been dead for over six months. Start a new discussion instead.