Kindly try using ButtonGroup component and add two JRadioButton components named male and female to the ButtonGroup object and then display it in a JFrame using setVisible(true); method.
The Below code should be useful :-
import java.awt.BorderLayout;
import java.awt.FlowLayout;
import javax.swing.ButtonGroup;
import javax.swing.JFrame;
import javax.swing.JRadioButton;
public class Rb extends JFrame {
Rb() {
JRadioButton male = new JRadioButton("male");
JRadioButton female = new JRadioButton("Female");
ButtonGroup bG = new ButtonGroup();
bG.add(male);
bG.add(female);
this.setSize(100, 200);
this.setLayout(new FlowLayout());
this.add(male);
this.add(female);
male.setSelected(true);
this.setVisible(true);
}
public static void main(String args[]) {
Rb j = new Rb();
}
}