Name: clC74495 Date: 06/02/99


(This is in Swing 1.1.1beta2, but applies to all versions)
The DefaultFocusManager is extremely slow when a container has many children. A testcase is given below.

The finger-of-blame goes to DefaultFocusManager.childrenTabOrder(), which uses a bubble sort[!!]. Replacing the bubble sort with a quick sort made the code about twenty times faster with the below (admittedly, extreme, but not entirely unrealistic) test case.

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

public class FocusTest extends JPanel
{
  static public void main(String[] args)
  {
    JFrame frame = new JFrame();
    frame.setContentPane(new FocusTest());
    frame.pack();
    frame.setVisible(true);
  }

  private FocusTest()
  {
    setLayout(new GridLayout(30, 30));
    for (int i = 0; i < 900; i++)
    {
      add(new JTextField("Field", 5));
    }
  }
}
(Review ID: 83175)
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