Creating Control Buttons with NetBeans IDE - Working with JCheckBox

(Page 3 of 5 )

In this section, we shall develop a small application with two check boxes, a button and a text box. The first check box stands for bold and the second for italic. The only difference between the above sample and this example is that we are using check boxes (instead of toggle buttons) and we wanted to apply the style only after clicking on the button.

Currently, I named the project "SampleJavaApplication1" and the form (or JFrame) "Sample04."

When the form (or JFrame) is created with "Sample04," the code behind it (only the constructor) would look something like the following:

  public class Sample04 extends javax.swing.JFrame {
    /** Creates new form Sample04 */
    public Sample04() {
      initComponents();
    }

Make changes to the above code fragment in such a way that it looks similar to the following:

  public class Sample04 extends javax.swing.JFrame {
    /** Creates new form Sample04 */
    public Sample04() {
      initComponents();
      this.setSize(300,200);
    }

In the above code, I explicitly defined the initial size of the frame. Before dropping all controls onto the form, set the layout to "null layout" (fig2), to ease our development for this article. Later in my upcoming articles, I shall introduce you to the other powerful and more efficient layouts. When you complete your form design, it should look something like the following (fig2).

For convenience in writing understandable code, I named those controls as follows:

  chkBold
  chkItalic
  btnShow
  txtMsg

I also gave a value to the Frame property "title" (using the property window), namely "Checkboxes: a Demo."

The code behind JCheckBox

Let us go through the code created behind JCheckBox. The entire code created by IDE is as follows:

    // Variables declaration - do not modify
    private javax.swing.JButton btnShow;
    private javax.swing.JCheckBox chkBold;
    private javax.swing.JCheckBox chkItalic;
    private javax.swing.JTextField txtMsg;

  private void initComponents() {
      chkBold = new javax.swing.JCheckBox();
      chkItalic = new javax.swing.JCheckBox();
      btnShow = new javax.swing.JButton();
      txtMsg = new javax.swing.JTextField();

      getContentPane().setLayout(null);

  setDefaultCloseOperation(
        javax.swing.WindowConstants.EXIT_ON_CLOSE);
      setTitle("Checkboxes: a demo");
      chkBold.setText("Bold");
      getContentPane().add(chkBold);
      chkBold.setBounds(40, 10, 130, 23);

      chkItalic.setText("Italic");
      getContentPane().add(chkItalic);
      chkItalic.setBounds(40, 30, 130, 23);

      btnShow.setText("Show");
      btnShow.addActionListener(new
          java.awt.event.ActionListener() {
        public void actionPerformed(java.awt.event.ActionEvent
evt)
  {
          btnShowActionPerformed(evt);
        }
      });

      getContentPane().add(btnShow);
      btnShow.setBounds(40, 60, 130, 23);

      txtMsg.setText("This is some message");
      getContentPane().add(txtMsg);
      txtMsg.setBounds(60, 100, 240, 20);

      pack();
    }

The explanation for the above code is very similar to that of the second section.

Next: The nucleus of JCheckBox >>
 

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