“Comparison method violates its general contract!” – TimSort and GridLayout
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 … Read more