JScrollPane 'laggy' scroll, with many components

Question

I have a form with 3045! components (1015 labels, 1015 textfields, 1015 comboboxes). All of them are in a JPanel and the JPanel in a JScrollPane. The problem is that the scrolling is 'laggy'. I have 4gb RAM in my PC so I don't think that this is the problem. What is wrong? In my task manager the application uses ~100mb.

My code:

final JScrollPane scrollPane_1 = new JScrollPane();
final JPanel panel = new JPanel();
panel.setLayout(null);
scrollPane_1.setViewportView(panel);
int y =0;
for(int i=0; i<1015;i++)
    {

            JLabel length = new JLabel();
            length.setBounds(10, y, 350, 20);
            length.setFont(new Font("Tahoma", Font.BOLD, 11));
            length.setEnabled(false);
            panel.add(length);
            panel.revalidate();

            JComboBox combo = new JComboBox();
            combo.setModel(new DefaultComboBoxModel(new String[] {"=", "!="}));
            combo.setBounds(10, y + 20, 70, 20);
            panel.add(combo);
            panel.revalidate();

            JTextField text = new JTextField();
            text.setBounds(10 + 80, y + 20, 200, 20);
            panel.add(text);
            panel.revalidate();
}

EDIT: I done a lot of tests and i realized that the lag exists only when i am using combo boxes, if i use eg textfields instead of comboboxes, the scrolling is normal...

Your code has problems in many respects. For one, you should not use null layout, and this is doubly wrong by trying to add a null layout container to a JScrollPane's viewport. I can't test your code because of this. But for my money, I'd use a JTable instead. — Hovercraft Full Of Eels, Jun 16 '13 at 22:09
The repeated revalidation is completely unnecessary but doesn't cause his main problems. — Hovercraft Full Of Eels, Jun 16 '13 at 22:13
My form is a jDialog, my container has GroupLayout. I create the panel only for the components. If i have not null layout, all components are painted in a 'row'.... — user1005633, Jun 16 '13 at 22:25
@user1005633: Consider use of other layouts. To wit: see my answer below. — Hovercraft Full Of Eels, Jun 16 '13 at 22:28
@user1005633 I am getting the same problem were you able to fix it? — Aequitas, Aug 14 '15 at 03:32

Hovercraft Full Of Eels · Answer 1 · 2013-06-16T22:45:43.137

When using a layout manager, your code doesn't seem all that laggy to me. Please test this:

import java.awt.Dimension;
import java.awt.Font;
import java.awt.GridLayout;

import javax.swing.*;

public class Foo2 {
   protected static final int PREF_W = 400;
   protected static final int PREF_H = 400;

   public static void main(String[] args) {
      final JScrollPane scrollPane_1 = new JScrollPane() {
         @Override
         public Dimension getPreferredSize() {
            return new Dimension(PREF_W, PREF_H);
         }
      };
      final JPanel panel = new JPanel();
      panel.setLayout(new GridLayout(0, 1));
      scrollPane_1.setViewportView(panel);
      for (int i = 0; i < 1015; i++) {
         JPanel innerPanel = new JPanel();
         innerPanel.setLayout(new BoxLayout(innerPanel, BoxLayout.LINE_AXIS));

         JLabel length = new JLabel("foo");
         length.setFont(new Font("Tahoma", Font.BOLD, 11));
         length.setEnabled(false);
         innerPanel.add(length);
         innerPanel.add(Box.createHorizontalGlue());

         JComboBox<String> combo = new JComboBox<String>();
         combo.setPrototypeDisplayValue("              ");
         combo.setModel(new DefaultComboBoxModel<String>(new String[] { "=", "!=" }));
         combo.setMaximumSize(combo.getPreferredSize());
         innerPanel.add(combo);

         JTextField text = new JTextField(10);
         JPanel textWrapper = new JPanel();
         textWrapper.add(text);
         innerPanel.add(textWrapper);

         panel.add(innerPanel);
      }
      JFrame frame = new JFrame();
      frame.add(scrollPane_1);
      frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
      frame.pack();
      frame.setLocationRelativeTo(null);
      frame.setVisible(true);
   }
}

Edit

How about with a JTable instead?

import java.awt.Dimension;
import java.awt.GridLayout;
import javax.swing.*;
import javax.swing.table.DefaultTableModel;

public class Foo3 {
   protected static final int PREF_W = 400;
   protected static final int PREF_H = 400;

   public static void main(String[] args) {
      final JScrollPane scrollPane_1 = new JScrollPane() {
         @Override
         public Dimension getPreferredSize() {
            return new Dimension(PREF_W, PREF_H);
         }
      };
      String[] columnNames = {"Foo", "Bar", "Baz"};
      String[][] data = new String[1015][3];
      for (int i = 0; i < data.length; i++) {
         data[i] = new String[]{"foo", "==", ""};
      }
      DefaultTableModel model = new DefaultTableModel(data, columnNames){
         @Override
         public boolean isCellEditable(int row, int column) {
            return (column != 0);
         }
      };
      JTable table = new JTable(model);
      table.getColumnModel().getColumn(1).setCellEditor(new DefaultCellEditor(
            new JComboBox<String>(new String[]{"==", "!="})));
      final JPanel panel = new JPanel();
      panel.setLayout(new GridLayout(0, 1));
      scrollPane_1.setViewportView(table);

      JFrame frame = new JFrame();
      frame.add(scrollPane_1);
      frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
      frame.pack();
      frame.setLocationRelativeTo(null);
      frame.setVisible(true);
   }
}

Ok, i tried the code but again the scroll is laggy.... I don't know what is going wrong :-( — user1005633, Jun 16 '13 at 22:34
@user1005633: [profile](http://stackoverflow.com/q/2064427/230513) your code, using HFOE's complete example for reference. — trashgod, Jun 17 '13 at 01:00
@Hovercraft Full Of Eels, ok the JTable is not laggy, but why when i use components the scroll is laggy? — user1005633, Jun 17 '13 at 08:27
I done a lot of tests and i realized that the lag exists only when i am using combo boxes, if i use eg textfields instead of comboboxes, the scrolling is normal... — user1005633, Jun 17 '13 at 09:29

score 2 · Answer 2 · edited Aug 14 '15 at 04:53

2

A note for all naive Swing programmers: all creation and manipulation of Swing Objects must be done on the AWT Event Thread, in a Runnable added to the Event Thread, when called from a different Thread, otherwise bad things can happen!

e.g.

 public static void main(String[] args) {
    SwingUtilities.invokeLater(new Runnable() {
      public void run() {
        // Swing object creation and modification code!
      }
    });
 }

Also learn how to use SwingWorker if you need to launch non-Swing code from Swing and run Swing code when it completes.

edited Aug 14 '15 at 04:53

Aequitas

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answered Jun 17 '13 at 01:27

Infernoz

131
4

Once you get enough rep. to make comments, please make answers like this a comment rather than an answer to the question (which it is not). +1 to help with that 'rep' thing.. – Andrew Thompson Jun 17 '13 at 05:53

Aequitas · Answer 3 · 2015-08-16T22:27:43.447

0

This is likely to be an issue with the JDK you are using. I have had similar problems when using JDK 1.8.0_45.

Downgrading your JDK to 1.8.0_31 should solve the issue that you are having with comboboxes lagging the scrolling.

Alternatively; add -Dsun.java2d.opengl=true to your VM arguments.

edited Aug 16 '15 at 22:27

answered Aug 16 '15 at 22:16

Aequitas

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JScrollPane 'laggy' scroll, with many components

3 Answers3