重写比较器遇到错误参数异常的问题
2016-07-28 18:58
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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:
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");
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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