A Fast Gateway to OOP in Java using NetBeans IDE - Working with more than one object
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Now, let us extend our testing with the same class “MyCalc.” Add one more label and call it “lblMsg2.” Modify your “ActionPerformed” as follows:
private void btnShowActionPerformed(java.awt.event.ActionEvent
evt) {
// TODO add your handling code here:
MyCalc obj1 = new MyCalc();
MyCalc obj2 = new MyCalc();
obj1.x = 10;
obj1.y = 20;
obj2.x = 100;
obj2.y = 200;
int r;
r = obj1.getSum();
this.lblMsg.setText("Sum = " + String.valueOf(r));
r = obj2.getSum();
this.lblMsg2.setText("Sum = " + String.valueOf
(r));
}
Once you execute your application (by pressing F5) and click on “show” you should see something like the following (Fig 09).
Within the above code, I created two objects (obj1 and obj2). After that, I assigned values to members of each of those objects. So, you can understand that the memory occupied by obj1 (for its members) would be totally different from the memory occupied by obj2 (for its members). In other words, we have two copies (or instances) of members in memory and the names of those copies (or instances) are ob1 and obj2. And the rest, I hope you can follow easily.
At the moment, I didn’t really concentrate on constructors (which already exist in our code). I just don’t want to risk confusing the readers. My future contributions would cover each and every aspect of OOP available in Java (but with NetBeans IDE).
The entire code for this article is freely available in the form of a zip file. That downloadable solution was developed using NetBeans 4.1 IDE together with Microsoft Windows 2003 Standard Edition. I didn’t really test it in any other version or platform. Please follow the respective platform documentation to get it working.
Any doubts, bugs, errors, suggestions, feedback etc. are highly appreciated at jag_chat@yahoo.com.
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