jdk7 中Collections.sort 异常

Collections.sort 异常

java.lang.IllegalArgumentException: Comparison method violates its general contract!
        at java.util.TimSort.mergeHi(TimSort.java:868)
        at java.util.TimSort.mergeAt(TimSort.java:485)
        at java.util.TimSort.mergeForceCollapse(TimSort.java:426)
        at java.util.TimSort.sort(TimSort.java:223)
        at java.util.TimSort.sort(TimSort.java:173)
        at java.util.Arrays.sort(Arrays.java:659)
        at java.util.Collections.sort(Collections.java:217)java.lang.IllegalArgum