[Update]
This solution unfortunately is not guaranteed to solve the problem in all cases. It is not enough to patch the default SortingFocusTraversalPolicy
of the KeyboardFocusManager.
I recommend to read the answer by Robin Loxley below, including his Update.
[/Update]
java.lang.IllegalArgumentException: Comparison method violates its general contract!
at java.util.TimSort.mergeHi(TimSort.java:868)
This problem is caused by a bug in javax.swing.LayoutComparator.
The following class installs a fixed version of javax.swing.LayoutComparator, which does not violate the contract of Comparator<Component>. This (or any other) fixed version of javax.swing.LayoutComparator should be submitted to Oracle by some Oracle contributor.
package ...;
import java.awt.Component;
import java.awt.ComponentOrientation;
import java.awt.FocusTraversalPolicy;
import java.awt.KeyboardFocusManager;
import java.awt.Window;
import java.lang.reflect.Field;
import java.util.Comparator;
import java.util.LinkedList;
import java.util.ListIterator;
import javax.swing.JRootPane;
import javax.swing.SortingFocusTraversalPolicy;
import javax.swing.UIManager;
/**
* Uses reflection to install a fixed version of {@link javax.swing.LayoutComparator} to solve the
* LayoutFocusTraversalPolicy/TimSort problem.
*
* <p>
* <code>java.lang.IllegalArgumentException: Comparison method violates its general contract!</code>
* <br/>
* {@code at java.util.TimSort.mergeHi(TimSort.java:868)}
* </p>
* <p>
* Usage: call {@code Class.forName(LayoutFocusTraversalPolicyTimSortBugFixer.class.getName())}
* before creating Swing components.
* </p>
*
* @author Burkhard Strauss
* @since Feb 2015
*/
public class LayoutFocusTraversalPolicyTimSortBugFixer
{
static
{
UIManager.getUI(new JRootPane()); // make Swing install the SortingFocusTraversalPolicy
final KeyboardFocusManager keyboardFocusManager = KeyboardFocusManager
.getCurrentKeyboardFocusManager();
final FocusTraversalPolicy focusTraversalPolicy = keyboardFocusManager
.getDefaultFocusTraversalPolicy();
boolean fixed = false;
if (focusTraversalPolicy instanceof SortingFocusTraversalPolicy)
{
try
{
final Field field = SortingFocusTraversalPolicy.class.getDeclaredField("comparator");
final boolean accessible = field.isAccessible();
try
{
field.setAccessible(true);
field.set(focusTraversalPolicy, new LayoutComparator());
fixed = true;
}
finally
{
field.setAccessible(accessible);
}
}
catch (final Exception e)
{
}
}
if (!fixed)
{
Loggers.getLoggerFor(LayoutFocusTraversalPolicyTimSortBugFixer.class).warn("could not fix the bug");
}
}
/**
* Fixed version of {@link javax.swing.LayoutComparator}.
* <p>
* Search for 'bugfix' in the code.
* </p>
*
* @author Burkhard Strauss
* @since Feb 2015
*/
@SuppressWarnings("serial")
private static class LayoutComparator implements Comparator<Component>, java.io.Serializable
{
private static final int ROW_TOLERANCE = 10;
private boolean horizontal = true;
private boolean leftToRight = true;
@SuppressWarnings("unused")
void setComponentOrientation(final ComponentOrientation orientation)
{
horizontal = orientation.isHorizontal();
leftToRight = orientation.isLeftToRight();
}
@Override
public int compare(Component a, Component b)
{
if (a == b)
{
return 0;
}
// Row/Column algorithm only applies to siblings. If 'a' and 'b'
// aren't siblings, then we need to find their most inferior
// ancestors which share a parent. Compute the ancestory lists for
// each Component and then search from the Window down until the
// hierarchy branches.
if (a.getParent() != b.getParent())
{
final LinkedList<Component> aAncestory = new LinkedList<Component>();
for (; a != null; a = a.getParent())
{
aAncestory.add(a);
if (a instanceof Window)
{
break;
}
}
if (a == null)
{
// 'a' is not part of a Window hierarchy. Can't cope.
throw new ClassCastException();
}
final LinkedList<Component> bAncestory = new LinkedList<Component>();
for (; b != null; b = b.getParent())
{
bAncestory.add(b);
if (b instanceof Window)
{
break;
}
}
if (b == null)
{
// 'b' is not part of a Window hierarchy. Can't cope.
throw new ClassCastException();
}
for (ListIterator<Component> aIter = aAncestory.listIterator(aAncestory.size()), bIter = bAncestory
.listIterator(bAncestory.size());;)
{
if (aIter.hasPrevious())
{
a = aIter.previous();
}
else
{
// a is an ancestor of b
return -1;
}
if (bIter.hasPrevious())
{
b = bIter.previous();
}
else
{
// b is an ancestor of a
return 1;
}
if (a != b)
{
break;
}
}
}
final int ax = a.getX(), ay = a.getY(), bx = b.getX(), by = b.getY();
int zOrder = a.getParent().getComponentZOrder(a) - b.getParent().getComponentZOrder(b);
{
//
// Here is the bugfix:
// Don't return 0 if a != b. This would violate the contract of
// Comparator<Component>.compare().
//
if (zOrder == 0)
{
zOrder = -1;
}
}
if (horizontal)
{
if (leftToRight)
{
// LT - Western Europe (optional for Japanese, Chinese, Korean)
if (Math.abs(ay - by) < ROW_TOLERANCE)
{
return (ax < bx) ? -1 : ((ax > bx) ? 1 : zOrder);
}
else
{
return (ay < by) ? -1 : 1;
}
}
else
{ // !leftToRight
// RT - Middle East (Arabic, Hebrew)
if (Math.abs(ay - by) < ROW_TOLERANCE)
{
return (ax > bx) ? -1 : ((ax < bx) ? 1 : zOrder);
}
else
{
return (ay < by) ? -1 : 1;
}
}
}
else
{ // !horizontal
if (leftToRight)
{
// TL - Mongolian
if (Math.abs(ax - bx) < ROW_TOLERANCE)
{
return (ay < by) ? -1 : ((ay > by) ? 1 : zOrder);
}
else
{
return (ax < bx) ? -1 : 1;
}
}
else
{ // !leftToRight
// TR - Japanese, Chinese, Korean
if (Math.abs(ax - bx) < ROW_TOLERANCE)
{
return (ay < by) ? -1 : ((ay > by) ? 1 : zOrder);
}
else
{
return (ax > bx) ? -1 : 1;
}
}
}
}
}
}
https://stackoverflow.com/questions/13575224
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