In this workout, you are asked to build a form for a Java class
Triangle by using Java Swing library.
Step 1: What is the expected outcome?
Triangle.jar. Double click the file to launch the form.
The form supports the following operations:
Data entry: The user will enter an integer into each of the three input fields.
Data processing: The user can click the
Validate Trianglebutton to see whether the three sides will form a triangle. The check result should be displayed in the output text area in the middle of the form.
The supplementary feature: If the user clicks the
Clearbutton, all the current text in the input fields and output text area will be removed.
Step 2: Download the NetBeans Project
A file structure has been given in a NetBeans project.
Download the project
Extract the zip file. It should contain the folder Triangle which is a NetBeans project.
Step 3: View the project files
Launch NetBeans IDE.
Open the project Triangle.
Under the Project tab, you should see a tree view of the packages
mytools and one class
Step 4: Create a New JFrame Form
package gui, create a new JFrame Form.
Name the form
After step 4, the file structure in the project should be like
Step 5: Add UI Components
Now you will add all the components to the form.
The required components are shown in the following Navigator view and layout view.
Step 6: Add a JLable
Add an additional component into the form: A JLabel showing your name.
Step 7: Bind an Event with the
If the user clicks the
Clear button, remove the current text in both input fields and output text area.
Step 8: Bind an Event with the
Validate Triangle Button
If the user clicks the
Validate Triangle button, the actions to be performed are listed below:
s1. Read text input from three input fields.
javax.swing.text.JTextComponent.getText() will read the text from the caller into a String.
s2. Extract an Integer from the raw text input.
As the content in text-based components are read as string, parse the integer value from a String, apply Integer.parseInt to the string.
For example, to extract an integer from the String
rawinput, the expression is
Triangle.isValid method to find out whether the three sides will form a triangle.
s4. Display the check result in the output text area which is located in the middle of the form.
javax.swing.text.JTextComponent.setText(r) will write a string r to the caller.
Step 9: Test the Form
Step 10: Submission
Compress the entire NetBeans project in a zip file.
Submit the zip file.