Resizing jpanel according to the components present in it

Question

In the below example, in the west side of the border layout, there is a parent panel which has a BoxLayout and couple of panels inside. The problem is that the west panel covers the whole area from top to bottom. The FlowLayout used for child panels inside the parent panel consume a lot of area. Is it possible to compress each JPanel according to the components? Also, it should remain the same even when the window is maximized?

import java.awt.BorderLayout;
import java.awt.EventQueue;

import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.border.EmptyBorder;
import javax.swing.JLabel;
import javax.swing.BoxLayout;
import javax.swing.JTextField;
import javax.swing.JCheckBox;
import javax.swing.JButton;

public class Sample extends JFrame {

    private JPanel contentPane;
    private JTextField textField;
    private JTextField textField_1;

    /**
     * Launch the application.
     */
    public static void main(String[] args) {
        EventQueue.invokeLater(new Runnable() {
            public void run() {
                try {
                    Sample frame = new Sample();
                    frame.setVisible(true);
                } catch (Exception e) {
                    e.printStackTrace();
                }
            }
        });
    }

    /**
     * Create the frame.
     */
    public Sample() {
        setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        setBounds(100, 100, 450, 300);
        contentPane = new JPanel();
        contentPane.setBorder(new EmptyBorder(5, 5, 5, 5));
        contentPane.setLayout(new BorderLayout(0, 0));
        setContentPane(contentPane);

        JPanel panel = new JPanel();
        contentPane.add(panel, BorderLayout.NORTH);

        JLabel lblNewLabel = new JLabel("New label");
        panel.add(lblNewLabel);

        JPanel panel_1 = new JPanel();
        contentPane.add(panel_1, BorderLayout.WEST);
        panel_1.setLayout(new BoxLayout(panel_1, BoxLayout.Y_AXIS));

        JPanel panel_2 = new JPanel();
        panel_1.add(panel_2);

        textField = new JTextField();
        panel_2.add(textField);
        textField.setColumns(2);

        textField_1 = new JTextField();
        panel_2.add(textField_1);
        textField_1.setColumns(2);

        JPanel panel_3 = new JPanel();
        panel_1.add(panel_3);

        JCheckBox chckbxNewCheckBox = new JCheckBox("New check box");
        panel_3.add(chckbxNewCheckBox);

        JPanel panel_4 = new JPanel();
        panel_1.add(panel_4);

        JButton btnNewButton = new JButton("New");
        panel_4.add(btnNewButton);

        JButton btnNewButton_1 = new JButton("New");
        panel_4.add(btnNewButton_1);
    }

}

Answer 1

One approach is to add panel_1 to an enclosing panel. The default FlowLayout conforms itself to the preferred size of the enclosed components when you pack() the enclosing Window. I've added a gray panel to CENTER as a placeholder; resize the frame to see the effect.

JPanel flowPanel = new JPanel();
flowPanel.add(panel_1);

As tested:

import java.awt.BorderLayout;
import java.awt.Color;
import java.awt.Dimension;
import java.awt.EventQueue;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.border.EmptyBorder;
import javax.swing.JLabel;
import javax.swing.BoxLayout;
import javax.swing.JTextField;
import javax.swing.JCheckBox;
import javax.swing.JButton;

public class Sample extends JFrame {

    private JPanel contentPane;
    private JTextField textField;
    private JTextField textField_1;

    /**
     * Launch the application.
     */
    public static void main(String[] args) {
        EventQueue.invokeLater(new Runnable() {
            @Override
            public void run() {
                try {
                    Sample frame = new Sample();
                    frame.pack();
                    frame.setVisible(true);
                } catch (Exception e) {
                    e.printStackTrace();
                }
            }
        });
    }

    /**
     * Create the frame.
     */
    public Sample() {
        setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        contentPane = new JPanel();
        contentPane.setBorder(new EmptyBorder(5, 5, 5, 5));
        contentPane.setLayout(new BorderLayout(0, 0));
        setContentPane(contentPane);

        JPanel panel = new JPanel();
        contentPane.add(panel, BorderLayout.NORTH);

        JLabel lblNewLabel = new JLabel("New label");
        panel.add(lblNewLabel);

        JPanel panel_1 = new JPanel();
        panel_1.setLayout(new BoxLayout(panel_1, BoxLayout.Y_AXIS));

        JPanel panel_2 = new JPanel();
        panel_1.add(panel_2);

        textField = new JTextField();
        panel_2.add(textField);
        textField.setColumns(2);

        textField_1 = new JTextField();
        panel_2.add(textField_1);
        textField_1.setColumns(2);

        JPanel panel_3 = new JPanel();
        panel_1.add(panel_3);

        JCheckBox chckbxNewCheckBox = new JCheckBox("New check box");
        panel_3.add(chckbxNewCheckBox);

        JPanel panel_4 = new JPanel();
        panel_1.add(panel_4);

        JButton btnNewButton = new JButton("New");
        panel_4.add(btnNewButton);

        JButton btnNewButton_1 = new JButton("New");
        panel_4.add(btnNewButton_1);

        JPanel flowPanel = new JPanel();
        flowPanel.add(panel_1);
        contentPane.add(flowPanel, BorderLayout.WEST);
        contentPane.add(new JPanel(){

            @Override
            public Dimension getPreferredSize() {
                return new Dimension(320, 240);
            }

            @Override
            public Color getBackground() {
                return Color.lightGray;
            }

        }, BorderLayout.CENTER);
    }

}