Java新手非常容易犯的一个错误

import java.util.ArrayList;
import java.util.List;
import java.util.concurrent.ThreadLocalRandom;

public class Test {

  public static void main(String[] args) {
    List<Long> l = new ArrayList<>();
    for (int i = 0; i < 100000; i++) {
      l.add(ThreadLocalRandom.current().nextLong());
    }
    l.sort((o1, o2) -> (int) (o1 - o2));
    // l.sort(Long::compare);
  }
}

Exception in thread "main" java.lang.IllegalArgumentException: Comparison method violates its general contract!
  at java.base/java.util.TimSort.mergeLo(TimSort.java:781)
  at java.base/java.util.TimSort.mergeAt(TimSort.java:518)
  at java.base/java.util.TimSort.mergeCollapse(TimSort.java:448)
  at java.base/java.util.TimSort.sort(TimSort.java:245)
  at java.base/java.util.Arrays.sort(Arrays.java:1516)
  at java.base/java.util.ArrayList.sort(ArrayList.java:1749)
  at io.ytcode.game.test/test.Test.main(Test.java:14)

// java.lang.Long
public static int compare(long x, long y) {
    return (x < y) ? -1 : ((x == y) ? 0 : 1);
}