Java tutorial
import java.awt.Color; import java.awt.Dimension; import java.awt.FlowLayout; import javax.swing.JFrame; import javax.swing.JPanel; public class Main { public static void main(String[] args) { JFrame frame = new JFrame(); frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); frame.setResizable(false); frame.setLayout(new FlowLayout(FlowLayout.LEFT, 0, 0)); JPanel navigation_panel_wrap = new JPanel() { @Override public Dimension getPreferredSize() { return new Dimension(250, 700); } }; JPanel content_panel_wrap = new JPanel() { @Override public Dimension getPreferredSize() { return new Dimension(750, 700); } }; content_panel_wrap.setBackground(Color.green); navigation_panel_wrap.setBackground(Color.red); frame.add(navigation_panel_wrap); frame.add(content_panel_wrap); frame.pack(); frame.setVisible(true); } }