Danson Wachira is a certified Trainer in Computer Science, Information Technology and related studies.
Lesson 55: Coding For Cancel And Add New Record Buttons In Java NetBeans
After learning how to successfully update a table record in Java NetBeans in the previous lesson, we shall now learn how to code for New and Cancel buttons in Java NetBeans. Any database application should be able to accept new data to be inserted in to a table.
We already have the Save button on the form but we’ll need another button to cancel the process of adding a record in case the user decides so. Create a space on the form preferably next to the New button and drop a button with Cancel as the caption.
How To Code For Insert New Record Button In Java NetBeans
Inserting a new record into a table will involve three buttons; New button will be used to clear the form ready for data entry, Save button will be used to insert the new record into a table and the Cancel button will be used to cancel insertion of a new record. Here is the current form now with the Cancel button added.
We’ll need to enable or disable some buttons but to know which buttons to enable or disable and when, we’ll need to understand the logical movement of the user on the form.
When the form loads, all the buttons should be enabled accept Cancel and Save buttons which should be disabled.
The Cancel and Save buttons should only be enabled when New button is clicked which automatically disables all the other buttons including itself so, the user can only save the record or cancel the process.
This follows the logical use of the form: it is impossible for the user to insert a new record while at the same time navigating through the records. We can separate these two operations by enabling or disabling buttons.
Locate for enabled property for Cancel and Save buttons as shown above and uncheck the enabled checkbox to disable each of them. So, when the form runs Cancel and Save buttons will be disabled as shown below.
When the user click on New button, all buttons including New button should be disabled except Cancel and Save buttons.
We cannot disable these buttons through their properties when the form is running but we can disable them programmatically through a code event in the New button.
Double click on New button to reveal the code stub and add the following code. A value of false means we are disabling the button and a values of true means we are enabling the button.
btnFirst.setEnabled( false );
btnPrev.setEnabled( false ) ;
btnNext.setEnabled( false );
btnLast.setEnabled( false );
btnUpdate.setEnabled( false );
btnDel.setEnabled( false );
btnNew.setEnabled( false );
btnSave.setEnabled( true );
btnCancel.setEnabled( true );
The above code and image show toggling of buttons only but there is more to that. When the user clicks on New button, all text fields should be cleared ready for new record. We need to get the current table row (an integer number) so that if the user happens to click on Cancel button we can re-populate the form with previous data. We’ll create a global Int variable to store the current table row as shown below.
To get the current table row when New button is clicked, we can use the getRow() method of ResultSet as shown below:
curRow = Rset.getRow( );
And to clear any field, we just replace the value with an empty string ("") for example, to clear Name field on the form we use:
We can also make data entry easier for users by populating some fields automatically for them.
For example, when the user click on New button, the field for Student ID should be occupied by the next available integer for Student ID. To do this, we just increment the last Student ID by 1 and set this number as the value for Student ID field, see the code below.
Rset.last( ); //Go to last record
int Id = Rset.getInt("StdID")+1; //Increment last record by 1
String Id2 = Integer.toString(Id); //Change integer to string
txtID.setText(Id2); //Set this number as new Student ID
The complete code inside New button should be contained in a try … catch block and should look as shown below:
Run the form now and the New button should be working as expected. Notice Student ID field has the next available integer for Student ID and that users don't have to type.
How To Code For Cancel Button Or Undo Button In Java NetBeans
The Cancel button will more or less operate to the opposite of New button. Using the row number in variable curRow, we’ll populate the form again with data from the current absolute row and then enable and disable appropriate buttons. This code should be inside a try … catch block. Here is the complete code for the Cancel button.
At this point the Cancel and New buttons should work as expected and they should also be able to synchronize in toggling appropriate buttons. As a test, run the form, click on Next button to record number two, then click on New button and then Cancel button. The form should return to its previous record and enable or disable appropriate buttons as shown above. In the next lesson, we’ll code for Save and Delete buttons.
Other related Hubs...
- How to use substring() method in Java
The Java substring() method is used to extract a given part of string from another string. This article illustrates how to use Java substring() method with strings and how to combine the method with other Java methods such a indexOf().
- How to handle logical errors in Java NetBeans
Use of in-built tools in Java programming language for tracing and correcting programming errors such as Breakpoints and Watches can assist a programmer in tracing difficult and tricky errors in a program.
- How to handle errors in Java programming
Debugging is one of the most daunting task in programming. This article discusses how to detect, isolate and correct common Java programming errors.
- Java class constructors and setter methods
Java constructors and Java setter methods are very useful when used in Java classes. They make the debugging of class code simpler and also add functionality to Java classes. Learn how to work with Java constructors and setter methods here.
Danson Wachira (author) from Nairobi, Kenya on May 01, 2013:
kidscrafts from Ottawa, Canada on April 30, 2013:
I can recognize some of the words in your code because of the course of Java Script I took about 15 years ago.... but without practice it doesn't help. At least, I am still able to work with the code in HTML when things are not going smoothly with Dreamweaver :-)
I love the way you organize your course.... that's why I suggested an e-book in my other message.
I wish my Java Script teacher was as organized as you are... that course was a nightmare! The guy was not organized at all :-(