Simple JFrame example in Java

simplegui.java

package fypsol.guiexamples.ex01;

import java.awt.FlowLayout;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;

import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JOptionPane;

public class MainClass {
	public static void main(String[] args) {

		JButton myButton = new JButton("Hello World");
		myButton.addActionListener(new ActionListener() {
			@Override
			public void actionPerformed(ActionEvent e) {
					
				JOptionPane.showMessageDialog(myButton, "Alert", "Hello World Clicked", JOptionPane.INFORMATION_MESSAGE);
			}
		});

		JFrame mJFrame = new JFrame("My First Jframe");
		mJFrame.setSize(250, 150);
		mJFrame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
		mJFrame.setLocationRelativeTo(null);
		// mJFrame.setLocation(400, 200);
		mJFrame.setResizable(false);
		mJFrame.add(myButton);
		mJFrame.setLayout(new FlowLayout());
		mJFrame.setVisible(true);

	}
}