"Comparison method violates its general contract!" - TimSort and GridLayout

Question

I made a color palette with a jPanel and a JLabel array in it. At first it worked well, but then i put some other jLabels out of the JPanel and added them some events. Now I keep getting this error: ``` Exception in thread "AWT-EventQueue-0" java.lang.IllegalArgumentException: Comparison method violates its general contract! at java.util.TimSort.mergeLo(TimSort.java:747) at java.util.TimSort.mergeAt(TimSort.java:483) at java.util.TimSort.mergeCollapse(TimSort.java:410) at java.util.TimSort.sort(TimSort.java:214) at java.util.TimSort.sort(TimSort.java:173) at java.util.Arrays.sort(Arrays.java:659) at java.util.Collections.sort(Collections.java:217) at javax.swing.SortingFocusTraversalPolicy.enumerateAndSortCycle(SortingFocusTraversalPolicy.java:136) at javax.swing.SortingFocusTraversalPolicy.getFocusTraversalCycle(SortingFocusTraversalPolicy.java:110) at javax.swing.SortingFocusTraversalPolicy.getFirstComponent(SortingFocusTraversalPolicy.java:435) at javax.swing.LayoutFocusTraversalPo…

Accepted Answer

It seems to me like you've hit a bug in the JDK since the error seems to come from Swing classes.

Options:

Define the property `java.util.Arrays.useLegacyMergeSort` as `true`. Either using in your code the line

```
System.setProperty("java.util.Arrays.useLegacyMergeSort", "true");
```

before any Swing code. As the first line in the `main` method should work.

Or adding

```
-Djava.util.Arrays.useLegacyMergeSort=true
```

to your starting options (in the console, or in the project properties in an IDE, Ant script, etc.)

Upgrade your JDK and see if the problem goes away

- Downgrade to Java 6

"Comparison method violates its general contract!" - TimSort and GridLayout

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