Java GUI JScrollBar How to set the length?

Question

I have the following GUI codded up but I would like to increase the length of the scroll bar on the right side.

Any Idea How to do this?

// test class that implements the gui stuff.
public class testing
{

    //variables
    private JFrame f = new JFrame("GUI TEST");

    private JPanel p = new JPanel();
    private JPanel p2 = new JPanel();
    private JPanel p3 = new JPanel();
    private JPanel p4 = new JPanel();
    private JPanel p5 = new JPanel();
    private JPanel p6 = new JPanel();
    private JPanel p7 = new JPanel();
    private JPanel p8 = new JPanel();
    private JPanel p9 = new JPanel();
    private JPanel p10 = new JPanel();
    private JPanel p11 = new JPanel();

    private JButton b1 = new JButton("Button");

    private JTextField tf1 = new JTextField("                                           ");
    private JTextField tf2 = new JTextField("                                           ");
    private JTextField tf3 = new JTextField("                                           ");

    private JTextArea ta1 = new JTextArea(10,45);

    private JLabel label1 = new JLabel("Label 1");
    private JLabel label2 = new JLabel("Label 2");
    private JLabel label3 = new JLabel("Label 3");
    private JLabel label4 = new JLabel("Label 4");

    private JScrollBar sb1 = new JScrollBar();

    //class constructor
    public testing()
    {
        gui();
    }

    public void gui()
    {
        //change length of scroll bar
        f.setVisible(true);
        f.setSize(600,300);
        p.add(label1);
        p.add(tf1);
        p2.add(label2);
        p2.add(tf2);
        p3.add(label3);
        p3.add(tf3);
        p4.add(sb1);
        p4.add(label4);
        p5.add(ta1);
        p6.add(b1);
        p4.setBackground(Color.GRAY);
        p9.setBackground(Color.GRAY);
        p10.setBackground(Color.GRAY);
        p11.setBackground(Color.GRAY);
        p9.add(p);
        p9.add(p2);
        p9.add(p3);
        p10.add(p5);
        p11.add(p6);
        //adds panels to frames
        f.add(p4, BorderLayout.EAST);
        f.add(p9, BorderLayout.NORTH);
        f.add(p10, BorderLayout.CENTER);
        f.add(p11, BorderLayout.PAGE_END);
    }

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

I think setting the viewPort's preferred size would work for you. — Gábor Bakos, Oct 21 '14 at 19:10
[Don't use `setPreferredSize()` when you really mean to override `getPreferredSize()`](http://stackoverflow.com/q/7229226/230513). — trashgod, Oct 21 '14 at 20:23
ScrollPane was required by the professor. So I just went with that. They also said leaving it the default size is ok. Thank you guys very much for your input; it was most helpful. — Charkins12, Oct 22 '14 at 21:02
@trashgod your links are most helpful. IDK how to give you credit for anything but thank you! — Charkins12, Oct 22 '14 at 21:06

score 2 · Accepted Answer · edited May 23 '17 at 12:27

Ordinarilly, you'd simply add your JTextArea to a JScrollPane, which handles the resizing behavior for you.

f.add(new JScrollPane(ta1), BorderLayout.CENTER);

For demonstration purposes, you can override the getPreferredSize() method of the JScrollBar to see the effect.

private JScrollBar sb1 = new JScrollBar(){

    @Override
    public Dimension getPreferredSize() {
        return new Dimension(
            super.getPreferredSize().width, ta1.getPreferredSize().height);
    }
};

In addition,

Swing GUI objects should be constructed and manipulated only on the event dispatch thread.
Use the appropriate constructor to establish the desired initial size of text components.
Use an appropriate layout to get the desired resizing behavior.

As tested:

import java.awt.BorderLayout;
import java.awt.Color;
import java.awt.Dimension;
import java.awt.EventQueue;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;
import javax.swing.JScrollBar;
import javax.swing.JTextArea;
import javax.swing.JTextField;

public class Testing {
    //variables
    private JFrame f = new JFrame("GUI TEST");

    private JPanel p = new JPanel();
    private JPanel p2 = new JPanel();
    private JPanel p3 = new JPanel();
    private JPanel p4 = new JPanel();
    private JPanel p5 = new JPanel();
    private JPanel p6 = new JPanel();
    private JPanel p9 = new JPanel();
    private JPanel p10 = new JPanel();
    private JPanel p11 = new JPanel();

    private JButton b1 = new JButton("Button");

    private JTextField tf1 = new JTextField(12);
    private JTextField tf2 = new JTextField(12);
    private JTextField tf3 = new JTextField(12);

    private JTextArea ta1 = new JTextArea(10, 45);

    private JLabel label1 = new JLabel("Label 1");
    private JLabel label2 = new JLabel("Label 2");
    private JLabel label3 = new JLabel("Label 3");
    private JLabel label4 = new JLabel("Label 4");

    private JScrollBar sb1 = new JScrollBar(){

        @Override
        public Dimension getPreferredSize() {
            return new Dimension(super.getPreferredSize().width, ta1.getPreferredSize().height);
        }
    };

    //class constructor
    public Testing() {
        gui();
    }

    public void gui() {
        p.add(label1);
        p.add(tf1);
        p2.add(label2);
        p2.add(tf2);
        p3.add(label3);
        p3.add(tf3);
        p4.add(sb1);
        p4.add(label4);
        p5.add(ta1);
        p6.add(b1);
        p4.setBackground(Color.GRAY);
        p9.setBackground(Color.GRAY);
        p10.setBackground(Color.GRAY);
        p11.setBackground(Color.GRAY);
        p9.add(p);
        p9.add(p2);
        p9.add(p3);
        p10.add(p5);
        p11.add(p6);
        //adds panels to frames
        f.add(p4, BorderLayout.EAST);
        f.add(p9, BorderLayout.NORTH);
        f.add(p10, BorderLayout.CENTER);
        f.add(p11, BorderLayout.PAGE_END);
        f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        f.pack();
        f.setVisible(true);
    }

    public static void main(String[] args) {
        EventQueue.invokeLater(() -> {
            new Testing();
        });
    }
}

Java GUI JScrollBar How to set the length?

1 Answers1

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