[Solved] Java collections.sort Error: Comparison method violates its general contract!

In the sorting code, it suddenly reports: comparison method vialates its general contract! The reasons are as follows:

In short, it can be understood as follows:

After JDK7, after the implementation of the compatible interface, the following three features should be satisfied:

1. Reflexivity: the comparison result of X and Y is opposite to that of Y and X

2. Transitivity: X > y,y> z. Then x > z。

3. Symmetry: x = y, then the comparison result of X and Z is the same as that of Y and Z

My code is as follows:

xyList.sort((left, right) ->
	if (x > y)
		return -1;
	if (x < y)
		return 1;
	// When equal returns a random
	if ((int) (Math.random() * 2) == 1)
		return 1;
	return -1;

Because when it is equal, it will always return a random result instead of a certain result. If it does not satisfy the symmetry of sorting, the above error will be reported

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