Making JPanel in JFrame scrollable

Question

package new1;

import javax.swing.*;

public class New1 {

    JFrame f = new JFrame("demo");
    JPanel p = new JPanel();
    JLabel l = new JLabel("one");
    JLabel la = new JLabel("two");
    JTextField t = new JTextField();
    JTextField ta = new JTextField();
    JScrollPane sc = new JScrollPane(p); // scrollbar with panel as constructor.

    New1() {
        f.add(p); // adding panel o the frame
        p.setVisible(true);
        p.setLayout(null);
        p.setSize(1400, 900);
        l.setBounds(10, 50, 100, 20); // setting dimension of labels
        la.setBounds(10, 100, 100, 20);
        t.setBounds(50, 100, 100, 20);   //setting dimension of Textfields
        tx.setBounds(50, 50, 100, 20);
        p.add(l);
        p.add(t);
        p.add(la);
        p.add(ta);
        p.add(tx);
        f.setLayout(null);
        f.setVisible(true);
        f.setSize(1400, 900);
        sc.setSize(1350, 700);  //setting size of scrollpane
        sc.setVisible(true);
        p.add(sc);       // adding to the panel
    }

    public static void main(String[] args) {
        new New1();
    }
}

Here I am adding some label to the JPanel and want to make this panel scrollable so please help. I am adding scroll pane with panel as constructor so the I can make panel as scrollable but I failed to do.

Answer 1

This is the way to go about achieving what you seem to need in this GUI.

    JPanel p = new JPanel(new GridBagLayout());
    ui.add(new JScrollPane(p, 
            JScrollPane.VERTICAL_SCROLLBAR_ALWAYS, 
            JScrollPane.HORIZONTAL_SCROLLBAR_NEVER));
    GridBagConstraints gbc = new GridBagConstraints();
    gbc.insets = new Insets(4,4,4,4);
    for (int ii=0; ii<50; ii++) {
        gbc.gridy = ii;
        gbc.gridx = 0;
        p.add(new JLabel("Label " + (ii+1)), gbc);
        gbc.gridx = 1;
        p.add(new JTextField("Text Field " + (ii+1), 20), gbc);
    }

This is how it might look.

Java GUIs have to work on different OS', screen size, screen resolution etc. using different PLAFs in different locales. As such, they are not conducive to pixel perfect layout. Instead use layout managers, or combinations of them along with layout padding and borders for white space.

It's also not possible to use a scroll pane when using null layouts. It is the layout managers that give the scroll pane (JScrollPane) the info. it needs to work properly.

Here is the complete code:

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

public class New2 {

    private JComponent ui = null;

    New2() {
        initUI();
    }

    public void initUI() {
        if (ui!=null) return;

        ui = new JPanel(new BorderLayout(4,4));
        ui.setBorder(new EmptyBorder(4,4,4,4));

        JPanel p = new JPanel(new GridBagLayout());
        ui.add(new JScrollPane(p, 
                JScrollPane.VERTICAL_SCROLLBAR_ALWAYS, 
                JScrollPane.HORIZONTAL_SCROLLBAR_NEVER));
        GridBagConstraints gbc = new GridBagConstraints();
        gbc.insets = new Insets(4,4,4,4);
        for (int ii=0; ii<50; ii++) {
            gbc.gridy = ii;
            gbc.gridx = 0;
            p.add(new JLabel("Label " + (ii+1)), gbc);
            gbc.gridx = 1;
            p.add(new JTextField("Text Field " + (ii+1), 20), gbc);
        }
    }

    public JComponent getUI() {
        return ui;
    }

    public static void main(String[] args) {
        Runnable r = new Runnable() {
            @Override
            public void run() {
                try {
                    UIManager.setLookAndFeel(UIManager.getSystemLookAndFeelClassName());
                } catch (Exception useDefault) {
                }
                New2 o = new New2();

                JFrame f = new JFrame(o.getClass().getSimpleName());
                f.setDefaultCloseOperation(JFrame.DISPOSE_ON_CLOSE);
                f.setLocationByPlatform(true);

                f.setContentPane(o.getUI());
                f.pack();
                Dimension d = f.getSize();
                f.setSize(new Dimension(d.width, 400));
                f.setMinimumSize(f.getSize());

                f.setVisible(true);
            }
        };
        SwingUtilities.invokeLater(r);
    }
}

Answer 2

but I am using any jpanel m using only frame and then adding some labels and tf

Actually you are using a JPanel. The content pane of a JFrame is a JPanel, so are actually adding the components to the frame.

Read the section from the Swing tutorial on Using Top Level Containers which explains the hierarchy in Swing.

So the simple solution to your problem is to:

1. add the components to a panel,
2. create a JScrollPane using the panel as a parameter and
3. then add the scroll pane to the frame.

This is the way it works, You can't make a frame scrollable.