Content
Create JRadioButton
Put JRadioButton group
Getting event JRadioButton

JRadioButton is an object that allows us to choose the attributes brittle as JCheckBox. However, we tend to use JRadioButton when the user wants to select only one of the attributes. For example, users choose the sex was just selected as M or F.

How to create JRadioButton – How to create JRadioButton

To create JRadioButton we use one of the following constructor:
– JRadioButton(): Create JRadioButton no text, not selected.
– JRadioButton(Action a): Create a JRadioButton event
– JRadioButton(Icon icon): Create JRadioButton with icon
– JRadioButton(Icon icon, boolean selected): Create JRadioButton the icon and set the selected or not
– JRadioButton(String text): Create JRadioButton with text
– JRadioButton(String text, boolean selected): Create JRadioButton with text and set to be selected or not
– JRadioButton(String text, Icon icon): Create JRadioButton with text and icons
– JRadioButton(String text, Icon icon, boolean selected): Create JRadioButton with text, icon and put option.

Now we will implement to create JFrame including 2 Boy and Girl is JRadioButton (Boy is selected by default) with 1 JLabel to their implementation show the results when selecting JRadioButton.

package nguyenvanquan7826.JRadioButton;

import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;
import javax.swing.JRadioButton;

public class MyRadioButton extends JFrame {
	private JRadioButton radBoy, radGirl;
	private JLabel lbGender;

	public MyRadioButton() {
		// add main panel
		add(createMainPanel());
		// set display
		setTitle("JRadioButton");
		setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
		setSize(200, 100);
		setLocationRelativeTo(null);
		setVisible(true);
	}

	// create main panel
	private JPanel createMainPanel() {
		JPanel panel = new JPanel();
		// add two radiobutton and a label to frame
		panel.add(radBoy = createRadioButton("Boy", true));
		panel.add(radGirl = createRadioButton("Girl", false));
		panel.add(lbGender = createLabel("You are a boy"));
		return panel;
	}

	// create a JRadioButton with name
	private JRadioButton createRadioButton(String name, boolean select) {
		JRadioButton rad = new JRadioButton(name, select);
		return rad;
	}

	// create a JLabel with text
	private JLabel createLabel(String text) {
		JLabel lb = new JLabel(text);
		return lb;
	}

	public static void main(String[] args) {
		new MyRadioButton();
	}
}

That has made JRadioButton, however, when you select your gender, there is no phenomenon happens with the JLabel, even at a time can select all 2 JRadioButton. So how to choose only one JRadioButton? how to capture the event for JRadioButton?

Put JRadioButton group – Set group for JRadioButton

To do that just allows the user to select one of the JRadioButton we need to put into a group JRadioButton – ButtonGroup. That is, we need to create a ButtonGroup and put them in there ButtonGroup. You edit the code of the method createMainPanel() as follows:

private JPanel createMainPanel() {
	JPanel panel = new JPanel();
	// add two radiobutton and a label to frame
	panel.add(radBoy = createRadioButton("Boy", true));
	panel.add(radGirl = createRadioButton("Girl", false));
	panel.add(lbGender = createLabel("You are a boy"));

	// create ButtonGroup for radBoy and radGirl
	ButtonGroup genderGroup = new ButtonGroup();
	// add radBoy and radGirl into Group
	genderGroup.add(radBoy);
	genderGroup.add(radGirl);

	return panel;
}

So now we only select the Boy or Girl.

Getting event JRadioButton – Action on JRadioButton

Next event will be captured for JRadioButton, it is similar to capture the event for JCheckBox. We need to implements the interface ItemListener to perform addItemListener for JRadioButton. Following the write method itemStateChanged to capture events. Check a JRadioButton is selected by the method isSelected().
We update the method createRadioButton as follows:

private JRadioButton createRadioButton(String name, boolean select) {
	JRadioButton rad = new JRadioButton(name, select);
	rad.addItemListener(this);
	return rad;
}

Next event is captured in the method itemStateChanged

private void changeSelect() {
	lbGender.setText("You are a " + (radBoy.isSelected() ? "boy" : "girl"));
}

@Override
public void itemStateChanged(ItemEvent e) {
	changeSelect();
}

Our complete code as follows:

package nguyenvanquan7826.JRadioButton;

import java.awt.event.ItemEvent;
import java.awt.event.ItemListener;

import javax.swing.ButtonGroup;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;
import javax.swing.JRadioButton;

public class MyRadioButton extends JFrame implements ItemListener {
	private JRadioButton radBoy, radGirl;
	private JLabel lbGender;

	public MyRadioButton() {
		// add main panel
		add(createMainPanel());
		// set display
		setTitle("JRadioButton");
		setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
		setSize(200, 100);
		setLocationRelativeTo(null);
		setVisible(true);
	}

	// create main panel
	private JPanel createMainPanel() {
		JPanel panel = new JPanel();
		// add two radiobutton and a label to frame
		panel.add(radBoy = createRadioButton("Boy", true));
		panel.add(radGirl = createRadioButton("Girl", false));
		panel.add(lbGender = createLabel("You are a boy"));

		// create ButtonGroup for radBoy and radGirl
		ButtonGroup genderGroup = new ButtonGroup();
		// add radBoy and radGirl into Group
		genderGroup.add(radBoy);
		genderGroup.add(radGirl);

		return panel;
	}

	// create a JRadioButton with name
	private JRadioButton createRadioButton(String name, boolean select) {
		JRadioButton rad = new JRadioButton(name, select);
		rad.addItemListener(this);
		return rad;
	}

	// create a JLabel with text
	private JLabel createLabel(String text) {
		JLabel lb = new JLabel(text);
		return lb;
	}

	private void changeSelect() {
		lbGender.setText("You are a " + (radBoy.isSelected() ? "boy" : "girl"));
	}

	@Override
	public void itemStateChanged(ItemEvent e) {
		changeSelect();
	}

	public static void main(String[] args) {
		new MyRadioButton();
	}

}

Read more: class JRadioButton, use JRadioButton