swing hello

Main.java

package org.abab;

import javax.swing.*;
import java.awt.*;

public class Main {

    public static void main(String[] args) {
        JFrame frame = new JFrame("Hello label");
        frame.setSize(300, 200);
        frame.setLocationRelativeTo(null);

        JLabel label = new JLabel();
        label.setText("Hello world!");

        JPanel panel = new JPanel();
        panel.add(label);

        Container contentPane = frame.getContentPane();
        contentPane.add(panel, BorderLayout.CENTER);
        frame.setContentPane(panel);
        frame.setVisible(true);
    }
}