Working with JFC/Swing Controls using NetBeans IDE

I already introduced the NetBeans IDE in my previous article "Developing Java Applications Using Netbeans."  We also managed to develop a "Hello World" application within the same article.  If you are new to NetBeans IDE, I strongly suggest you go through that article first, before proceeding with this one.

The entire code for this article is freely available in the form of a zip file.  That downloadable solution is developed using NetBeans 4.1 IDE.  I didn't really test it in any other version.

Working with text boxes, buttons, labels: Design

In this section, we shall develop a small application with two text boxes, three labels and a button.  When the button is clicked, it should automatically add the two numbers available in two text boxes and show the result in a label ('lblResult').  Currently, I named the project "SampleJavaApplication1" and the form (or JFrame) "Sample01."

When the form (or JFrame) is created with "Sample01," the code behind it (only the constructor) would look something like the following:

public class Sample01 extends javax.swing.JFrame {

    /** Creates new form Sample01 */
    public Sample01() {
        initComponents();
    }

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

  public class Sample01 extends javax.swing.JFrame {

    /** Creates new form Sample01 */
    public Sample01() {
        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" (fig1), 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 (fig1).

To keep the written code understandable, I named those controls as follows:

  txtFirst
  txtSecond
  lblEnterFirst
  lblEnterSecond
  lblResult
  btnSum

I also gave a value to the Frame property "title" (using the property window), namely "Sample for adding two numbers."