重写比较器遇到错误参数异常的问题

来源：互联网发布：迈视高清网络摄像机编辑：程序博客网时间：2024/05/16 12:34

下述代码实现了按照map的value排序，但不希望两个值相同时返回0，即发生覆盖

        Collections.sort(sortedInterfaceReqCount, new Comparator<Map.Entry<String, Integer>>() {            @Override            public int compare(Map.Entry<String, Integer> o1, Map.Entry<String, Integer> o2) {                return o1.getValue() > o2.getValue() ? -1 : 1;            }        });

但，会报如下异常：

Exception in thread "main" 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:408)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 com.qunar.training.Question1.RequestMessage.sortInterfaceReqCount(RequestMessage.java:67)at com.qunar.training.Question1.AccessLogProcessor.process(AccessLogProcessor.java:60)at com.qunar.training.Question1.AccessLogProcessor.readFile(AccessLogProcessor.java:32)at com.qunar.training.Question1.RequestMessageShow.process(RequestMessageShow.java:40)at com.qunar.training.Question1.RequestMessageShow.show(RequestMessageShow.java:30)at com.qunar.training.Question1.Main.main(Main.java:14)at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57)at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)at java.lang.reflect.Method.invoke(Method.java:606)at com.intellij.rt.execution.application.AppMain.main(AppMain.java:134)

经过在网上查询说是java1.7的一个bug，在程序最前面加上下面一句就可以：

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

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