import java.awt.BorderLayout;
import java.awt.Color;
import java.awt.Dimension;
import java.awt.FlowLayout;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;
public class Main extends JFrame {
public static void main(String args[]) {
Main t = new Main();
JPanel mainPanel = new JPanel(new BorderLayout());
JLabel l = new JLabel("hello world");
l.setOpaque(true);
l.setBackground(Color.RED);
JPanel extraPanel = new JPanel(new FlowLayout());
l.setPreferredSize(new Dimension(100, 100));
extraPanel.setBackground(Color.GREEN);
extraPanel.add(l);
mainPanel.add(extraPanel, BorderLayout.CENTER);
t.setContentPane(mainPanel);
t.setDefaultCloseOperation(EXIT_ON_CLOSE);
t.setSize(400, 200);
t.setVisible(true);
}
}