Java Swing Scroll-able JPanel with Multiple Panels on Frame

Question

I have a JFrame and it has two JPanels. First is the header and then below it is the main content panel. I want to make my second content panel to be scroll-able but even though the scrollbar appears on the panel it doesn't seem to expand to its true height. In my second JPanel called p2, I am adding 20 small JPanels which should cause it to expand in height but it doesn't do that. Below is my Code:

public class DisplayItems3{

    public static void main(String[] args) {

        JFrame frame = new JFrame();

        final int FRAME_WIDTH  = 1000;
        final int FRAME_HEIGHT = 1000;

        frame.setSize(FRAME_WIDTH, FRAME_HEIGHT);
        frame.setTitle("Home Library");
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        frame.setLayout(new FlowLayout());

        //Top Panel
        JPanel p1 = new JPanel();
        p1.setLayout(new FlowLayout());
        p1.setBackground(Color.LIGHT_GRAY);
        p1.setPreferredSize(new Dimension(950, 100));

        JLabel l1 = new JLabel("All Library Items");
        l1.setForeground(Color.BLACK);
        l1.setPreferredSize(new Dimension(900, 50));
        l1.setFont(l1.getFont().deriveFont(30.0f));

        p1.add(l1);

        //Content Panel
        JPanel p2 = new JPanel();
        p2.setLayout(new FlowLayout());
        p2.setBackground(Color.LIGHT_GRAY);
        p2.setPreferredSize(new Dimension(950, 800));
        p2.setAutoscrolls(true);

        JScrollPane scrollPane = new JScrollPane(p2);
        scrollPane.setHorizontalScrollBarPolicy(JScrollPane.HORIZONTAL_SCROLLBAR_NEVER);
        scrollPane.setVerticalScrollBarPolicy(JScrollPane.VERTICAL_SCROLLBAR_AS_NEEDED);
        scrollPane.setBounds(0, 0, 950, 800);

        JPanel contentPane = new JPanel(null);
        contentPane.setPreferredSize(new Dimension(950, 800));
        contentPane.add(scrollPane);

        for(int i = 0; i < 20; i++) {

            JPanel sp1 = new JPanel();
            sp1.setLayout(new FlowLayout());
            sp1.setBackground(Color.WHITE);
            sp1.setPreferredSize(new Dimension(900, 180));

            p2.add(sp1);    

        }


        //contentPane.add(p2);
        frame.add(p1);
        //frame.add(p2);
        //frame.setContentPane(contentPane);
        frame.add(contentPane);

        frame.setDefaultCloseOperation(JFrame.DISPOSE_ON_CLOSE);
        frame.setVisible(true);

    }

}

Update using JList

It didn't work!

public class JListTest {

    public static void main(String[] args) {

        JFrame frame = new JFrame();

        final int FRAME_WIDTH  = 1000;
        final int FRAME_HEIGHT = 1000;

        frame.setSize(FRAME_WIDTH, FRAME_HEIGHT);
        frame.setTitle("Home Library");
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        frame.setLayout(new FlowLayout());

        //Top Panel
        JPanel p1 = new JPanel();
        p1.setLayout(new FlowLayout());
        p1.setBackground(Color.LIGHT_GRAY);
        p1.setPreferredSize(new Dimension(950, 100));

        JLabel l1 = new JLabel("All Library Items");
        l1.setForeground(Color.BLACK);
        l1.setPreferredSize(new Dimension(900, 50));
        l1.setFont(l1.getFont().deriveFont(30.0f));

        p1.add(l1);

        JList ll1 = new JList();
        ll1.setLayout(new FlowLayout());
        ll1.setBackground(Color.LIGHT_GRAY);
        ll1.setPreferredSize(new Dimension(950, 800));
        ll1.setAutoscrolls(true);

        JScrollPane scrollPane = new JScrollPane(ll1);
        scrollPane.setHorizontalScrollBarPolicy(JScrollPane.HORIZONTAL_SCROLLBAR_NEVER);
        scrollPane.setVerticalScrollBarPolicy(JScrollPane.VERTICAL_SCROLLBAR_ALWAYS);
        scrollPane.setBounds(0, 0, 950, 800);

        for(int i = 0; i < 20; i++) {

            JPanel sp1 = new JPanel();
            sp1.setLayout(new FlowLayout());
            sp1.setBackground(Color.WHITE);
            sp1.setPreferredSize(new Dimension(900, 180));

            ll1.add(sp1);    

        }


        //contentPane.add(p2);
        frame.add(p1);
        frame.add(scrollPane);
        //frame.setContentPane(contentPane);
        //frame.add(contentPane);

        frame.setDefaultCloseOperation(JFrame.DISPOSE_ON_CLOSE);
        frame.setVisible(true);

    }

}

Problem Solved: Working Code

public class scrollTest2 {

    public static void main(String[] args)
    {
        JFrame frame = new JFrame();

        final int FRAME_WIDTH  = 1000;
        final int FRAME_HEIGHT = 1000;

        frame.setSize(FRAME_WIDTH, FRAME_HEIGHT);
        frame.setTitle("Home Library");
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        frame.setLayout(new BorderLayout());

        JLabel m1 = new JLabel("safsd");

        JPanel panel = new JPanel();
        panel.setLayout(new BoxLayout(panel, BoxLayout.Y_AXIS));
        panel.setAutoscrolls(true);
        frame.add(panel,BorderLayout.NORTH);

        JScrollPane scrollPane = new JScrollPane(panel);
        scrollPane.setHorizontalScrollBarPolicy(JScrollPane.HORIZONTAL_SCROLLBAR_AS_NEEDED);
        scrollPane.setVerticalScrollBarPolicy(JScrollPane.VERTICAL_SCROLLBAR_AS_NEEDED);
        scrollPane.setBounds(50, 30, 800, 800);

        JPanel contentPane = new JPanel(null);
        contentPane.setPreferredSize(new Dimension(900, 900));
        contentPane.add(scrollPane);

        for(int i = 0; i < 30; i++) {

            JPanel sp1 = new JPanel();
            sp1.setLayout(new FlowLayout());
            sp1.setBackground(Color.WHITE);
            sp1.setPreferredSize(new Dimension(900, 180));

            JPanel ssp1 = new JPanel();
            ssp1.setLayout(new FlowLayout());
            ssp1.setBackground(Color.WHITE);
            ssp1.setPreferredSize(new Dimension(500, 170));

            JPanel ssp2 = new JPanel();
            ssp2.setLayout(new FlowLayout());
            ssp2.setBackground(Color.WHITE);
            ssp2.setPreferredSize(new Dimension(350, 170));

            JLabel l3 = new JLabel("Title: ");
            l3.setForeground(Color.BLACK);
            l3.setPreferredSize(new Dimension(100, 20));
            JTextField t1 = new JTextField("Electronic Basics");
            t1.setPreferredSize(new Dimension(320, 20));

            JLabel l4 = new JLabel("Type: ");
            l4.setForeground(Color.BLACK);
            l4.setPreferredSize(new Dimension(100, 20));
            JTextField t2 = new JTextField("Book");
            t2.setPreferredSize(new Dimension(320, 20));

            JLabel l5 = new JLabel("Authors: ");
            l5.setForeground(Color.BLACK);
            l5.setPreferredSize(new Dimension(100, 20));
            JTextField t3 = new JTextField("Bob the Builder");
            t3.setPreferredSize(new Dimension(320, 20));

            JLabel l6 = new JLabel("Publisher: ");
            l6.setForeground(Color.BLACK);
            l6.setPreferredSize(new Dimension(100, 20));
            JTextField t4 = new JTextField("ABC Company");
            t4.setPreferredSize(new Dimension(320, 20));

            JLabel l7 = new JLabel("Location: ");
            l7.setForeground(Color.BLACK);
            l7.setPreferredSize(new Dimension(100, 20));
            JTextField t5 = new JTextField("Shelf 1 Row 3");
            t5.setPreferredSize(new Dimension(320, 20));

            JLabel l8 = new JLabel("Status: ");
            l8.setForeground(Color.BLACK);
            l8.setPreferredSize(new Dimension(100, 20));
            JTextField t6 = new JTextField("Available");
            t6.setPreferredSize(new Dimension(320, 20));

            JButton btnLoanHistory = new JButton("Loan History");
            btnLoanHistory.setPreferredSize(new Dimension(300, 20));
            JButton btnLoanItem = new JButton("Loan Item");
            btnLoanItem.setPreferredSize(new Dimension(300, 20));
            JButton btnProcessReturn = new JButton("Process Return");
            btnProcessReturn.setPreferredSize(new Dimension(300, 20));

            ssp1.add(l3);
            ssp1.add(t1);
            ssp1.add(l4);
            ssp1.add(t2);
            ssp1.add(l5);
            ssp1.add(t3);
            ssp1.add(l6);
            ssp1.add(t4);
            ssp1.add(l7);
            ssp1.add(t5);
            ssp1.add(l8);
            ssp1.add(t6);

            ssp2.add(btnLoanHistory);
            ssp2.add(btnLoanItem);
            ssp2.add(btnProcessReturn);

            sp1.add(ssp1);
            sp1.add(ssp2);
            panel.add(sp1); 

        }

        frame.add(m1, BorderLayout.NORTH);
        frame.add(contentPane, BorderLayout.CENTER);
        frame.pack();
        frame.setDefaultCloseOperation(JFrame.DISPOSE_ON_CLOSE);
        frame.setVisible(true);
    }

}

What will ultimately appear in the '20 panels'? The 'Library items' suggests either a `JList` with appropriate renderer or a `JTable` would be better for this purpose. — Andrew Thompson, Feb 27 '17 at 13:30
each of 20 panel would contain a form elements to display day and few buttons that would provide addition functionality. — Saad A, Feb 27 '17 at 13:34
That could be achieved with a single selection `JList` with each list item showing the date, with the buttons outside (e.g. below) the list (outside the scroll pane). — Andrew Thompson, Feb 27 '17 at 13:43
I am a little confused can you provide a very simple example — Saad A, Feb 27 '17 at 13:54
*"I am a little confused .."* Which part are you having trouble understanding? *"can you provide a very simple example"* I could provide an example, though whether it is 'simple' is up to the observer to judge (what I think is simple might not be what you think is simple). But I won't provide a code sample because SO is not a code generation machine. — Andrew Thompson, Feb 27 '17 at 14:15
fair enough, but instead of me finding a who new solution to the problem, could you perhaps point out why my current code is not working? — Saad A, Feb 27 '17 at 14:18
*"could you perhaps point out why my current code is not working?"* `contentPane = new JPanel(null);` and `contentPane.setPreferredSize(...);` see [this question](http://stackoverflow.com/questions/7229226/should-i-avoid-the-use-of-setpreferredmaximumminimumsize-methods-in-java-swi), the answers in [this question](http://stackoverflow.com/questions/6592468/why-is-it-frowned-upon-to-use-a-null-layout-in-swing) and [null layout is evil](http://www.leepoint.net/GUI/layouts/nulllayout.html). At first view that's what I think is causing problems — Frakcool, Feb 27 '17 at 14:22
Ultimately I want each one of the white boxes inside the scrollable panel to be JPanel, so I should create a JList of JPanels and add each sp1 component to it? — Saad A, Feb 27 '17 at 14:29
Do you still need help? You edited your question with a *"Working code"* text, but not sure if it was the "solved" code or the "I still need help with this code"... — Frakcool, Feb 27 '17 at 17:25

Julien Gauthier · Answer 1 · 2017-02-27T15:19:43.090

Add p1 into contentPane, not into frame The example above is good. Have a nice day.

import java.awt.BorderLayout;
import java.awt.Color;
import java.awt.Dimension;
import java.awt.FlowLayout;
import java.awt.GridLayout;

import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;
import javax.swing.JScrollPane;
import javax.swing.border.LineBorder;

public class DisplayItems3 {

    public static void main(final String[] args) {

        JFrame frame = new JFrame();

        final int FRAME_WIDTH = 1000;
        final int FRAME_HEIGHT = 1000;

        frame.setSize(FRAME_WIDTH, FRAME_HEIGHT);
        frame.setTitle("Home Library");
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        frame.setLayout(new FlowLayout());

        // Top Panel
        JPanel p1 = new JPanel();
        p1.setLayout(new FlowLayout());
        p1.setBackground(Color.LIGHT_GRAY);
        p1.setPreferredSize(new Dimension(950, 100));

        JLabel l1 = new JLabel("All Library Items");
        l1.setForeground(Color.BLACK);
        l1.setPreferredSize(new Dimension(900, 50));
        l1.setFont(l1.getFont().deriveFont(30.0f));

        p1.add(l1);

        // Content Panel
        JPanel p2 = new JPanel();
        p2.setLayout(new GridLayout(-1, 1));
        p2.setBackground(Color.LIGHT_GRAY);
        p2.setPreferredSize(new Dimension(950, 800));
        p2.setAutoscrolls(true);

        JScrollPane scrollPane = new JScrollPane(p2);
        scrollPane.setHorizontalScrollBarPolicy(
                JScrollPane.HORIZONTAL_SCROLLBAR_NEVER);
        scrollPane.setVerticalScrollBarPolicy(
                JScrollPane.VERTICAL_SCROLLBAR_AS_NEEDED);
        scrollPane.setBounds(0, 0, 950, 800);

        JPanel contentPane = new JPanel(new BorderLayout());
        contentPane.setPreferredSize(new Dimension(950, 800));
        contentPane.add(scrollPane, BorderLayout.CENTER);

        for (int i = 0; i < 20; i++) {

            JPanel sp1 = new JPanel();
            sp1.setLayout(new FlowLayout());
            sp1.setBackground(Color.WHITE);
            sp1.setPreferredSize(new Dimension(900, 180));
            sp1.setBorder(new LineBorder(Color.RED));

            p2.add(sp1);

        }

        // contentPane.add(p2);
        contentPane.add(p1, BorderLayout.NORTH);
        // frame.add(p2);
        // frame.setContentPane(contentPane);
        frame.add(contentPane);

        frame.setDefaultCloseOperation(JFrame.DISPOSE_ON_CLOSE);
        frame.setVisible(true);

    }

}

Thank you for the effort, however when I ran this code it doesn't show all 20 panels, only 4. — Saad A, Feb 27 '17 at 15:05
No no it works, you only see 4 panel because of the layout of p2. FlowLayout isn't good. look, i change the code in my example with a gridLayout. you'll see. — Julien Gauthier, Feb 27 '17 at 15:18
done, you can now try this code wich display correctly your 20 panels. — Julien Gauthier, Feb 27 '17 at 15:20
thank you, but one thing it shrink the size of my item Jpanels sp1 and second, if try this will 200 jpanel it doesn't really work. The scroll shouldn't effect the size of my items. — Saad A, Feb 27 '17 at 16:33

Java Swing Scroll-able JPanel with Multiple Panels on Frame

1 Answers1