Java Swing Radio Buttons

Prerequisites

Has satisfactory background on Java Swing (esp. learned parts I and II)

Radio buttons are circular graphical components that contain mutually exclusive options—meaning they must choose one option but not more than one option.

Using Radio Buttons

Radio buttons can be put easily on the JFrame form, but implementing its functionality can be a somewhat heavy task. Regardless, the steps of adding radio buttons are shown below and explained in detail.

Create a JFrame form if you haven't created one, then recreate this design. Radio buttons and normal buttons are available at the Palette Window. After recreating the design, name the options or the labels of radio buttons whatever you want. In this instance, I named them from letters A to D.

After doing so, rename the variables of these options. If you forgot how to do it, relearn the previous parts of Java Swing to still get on track. In this instance, I renamed them from optionA to optionD. While renaming them, also rename the variable of the button.

Drag the Button Group from the Palette window, then drop it anywhere within the form to insert the component. Change the button group's variable name after inserting to ensure cleanliness of the codebase.

At the Navigator window, select the four options. After selecting those, at the Properties tab, change the value of the buttonGroup property to the button group that we recently created.

Programming the Radio Buttons

The coding part can be sometimes fun because this is where we implement its functionality and making it work.

Browse the button's method by double-clicking the button from the Design tab, then insert this following code block. This code block is basically full of if-else statements; it is the easiest way to implement the radio buttons. Each condition is checking whether any of these (top three) options is selected, if neither of these top three conditions are satisfied, the else statement is executed, which is the last option.

Each statement, inside the if blocks, is merely one line of code that shows the dialog and displays the name of a selected option.

You can modify the code of the control flow if you think of any shorter block of code. But as of now, this is the best and known way to check each condition—whether if an option is selected—and execute the respective statement where the condition satisfies.

Run the application, then choose an option and click the button. Once clicked, you can see the dialog popped up and display the name of the selected option.

And voilà, you've successfully implemented the radio buttons and use it for various purposes, such as multiple choice questions, etc.

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