Java Collections.sort（）没有比较元素

Question

我有一个IndexList的ArrayList，它是一个带有字符串的简单类，以及两个整数和下面显示的compareTo()方法。我的问题是，当我在ArrayList上调用Collections.sort()时，大多数情况下所有的排序都是正确的，但有时候两个元素永远不会进行比较，导致排序错误。

一些供参考代码：

//Get a list of the values 
ArrayList<IndexEntry<T>> cleanEntries = new ArrayList<IndexEntry<T>>(matches.get(query).values()); 

//Sort Files/URLS 
Collections.sort(cleanEntries); 

public int compareTo(IndexEntry<T> other) { 
    if(this.occurrenceCount < other.getOccurrenceCount()){ 
     return 1; 
    } 
    else if(this.occurrenceCount > other.getOccurrenceCount()){ 
     return -1; 
    } 
    else{//Need to compare Initial Positions 
     if(this.firstOccurrence == other.getFirstOccurrence()){ 
      return this.getLocationName().compareTo(other.getLocationName()); 
     } 
     else if(this.firstOccurrence > other.getFirstOccurrence()){ 
      return 1; 
     } 
     else{ 
      return -1; 
     } 
    } 
} 

这里是所有IndexEntry的字母“C”的一些输出例如：如何发生次数和初次发生后，被确定为

c 
"index.html", 6, 2 
"chickadee.html", 3, 2 
"cuckoo.html", 3, 2 
"crow.html", 3, 2 
"crane.html", 3, 2 
"cardinal.html", 3, 2 
"quail.html", 2, 2 
"robin.html", 2, 2 
"finch.html", 2, 2 
"kingfisher.html", 2, 2 
"swan.html", 2, 2 
"turkey.html", 2, 2 
"ibis.html", 2, 2 
"falcon.html", 2, 2 
"albatross.html", 2, 2 
"tern.html", 2, 2 
"dove.html", 2, 2 
"mockingbird.html", 2, 2 
"owl.html", 2, 2 
"sparrow.html", 2, 2 
"hawk.html", 2, 2 
"magpie.html", 2, 2 
"nighthawk.html", 2, 2 
"gull.html", 2, 2 
"bluebird.html", 2, 2 
"raven.html", 2, 2 
"blackbird.html", 2, 2 
"sandpiper.html", 2, 2 
"pheasant.html", 2, 2 
"roadrunner.html", 2, 2 
"duck.html", 2, 2 
"vulture.html", 2, 2 
"pigeon.html", 2, 2 
"heron.html", 2, 2 
"stork.html", 2, 2 
"warbler.html", 2, 2 
"woodpecker.html", 2, 2 
"hummingbird.html", 2, 2 
"mallard.html", 2, 2 
"osprey.html", 2, 2 
"swallow.html", 2, 2 
"wren.html", 2, 2 
"goose.html", 2, 2 
"meadowlark.html", 2, 2 
"pelican.html", 2, 2 
"starling.html", 2, 2 
"loon.html", 2, 2 
"eagle.html", 2, 2 
"puffin.html", 2, 2 
"egret.html", 2, 2 

公告是一样的，它停止排序。正确的输出是：

c 
"index.html", 6, 2 
"cardinal.html", 3, 2 
"chickadee.html", 3, 2 
"crane.html", 3, 2 
"crow.html", 3, 2 
"cuckoo.html", 3, 2 
"albatross.html", 2, 2 
"blackbird.html", 2, 2 
"bluebird.html", 2, 2 
"dove.html", 2, 2 
"duck.html", 2, 2 
"eagle.html", 2, 2 
"egret.html", 2, 2 
"falcon.html", 2, 2 
"finch.html", 2, 2 
"goose.html", 2, 2 
"gull.html", 2, 2 
"hawk.html", 2, 2 
"heron.html", 2, 2 
"hummingbird.html", 2, 2 
"ibis.html", 2, 2 
"kingfisher.html", 2, 2 
"loon.html", 2, 2 
"magpie.html", 2, 2 
"mallard.html", 2, 2 
"meadowlark.html", 2, 2 
"mockingbird.html", 2, 2 
"nighthawk.html", 2, 2 
"osprey.html", 2, 2 
"owl.html", 2, 2 
"pelican.html", 2, 2 
"pheasant.html", 2, 2 
"pigeon.html", 2, 2 
"puffin.html", 2, 2 
"quail.html", 2, 2 
"raven.html", 2, 2 
"roadrunner.html", 2, 2 
"robin.html", 2, 2 
"sandpiper.html", 2, 2 
"sparrow.html", 2, 2 
"starling.html", 2, 2 
"stork.html", 2, 2 
"swallow.html", 2, 2 
"swan.html", 2, 2 
"tern.html", 2, 2 
"turkey.html", 2, 2 
"vulture.html", 2, 2 
"warbler.html", 2, 2 
"woodpecker.html", 2, 2 
"wren.html", 2, 2 

不管怎么说，就像我说的我都省略了大量的信息，但如果有的话，想到我会很感激的想法。事实上，在创建ArrayList之后，“匹配”数据结构不会被修改。编辑： 嘿，我还在阅读你的回应。非常感谢您的快速帮助！这里是整个IndexEntry类，因为你们几个问：

class IndexEntry<extends Comparable<T>> implements Comparable<IndexEntry<T>>{ 
     private T theLocation; 
     private Integer occurrenceCount; 
     private Integer firstOccurrence; 

     public IndexEntry(T location, Integer firstOcc, Integer occCount){ 
      theLocation = location; 
      occurrenceCount = occCount; 
      firstOccurrence = firstOcc; 
     } 

     public int compareTo(IndexEntry<T> other) {   
      if(this.occurrenceCount < other.getOccurrenceCount()){ 
       return 1; 
      } 
      else if(this.occurrenceCount > other.getOccurrenceCount()){ 
       return -1; 
      } 
      else{//Need to compare Initial Positions 
       if(this.firstOccurrence == other.getFirstOccurrence()){ 
        return this.getLocationName().compareTo(other.getLocationName()); 
       } 
       else if(this.firstOccurrence > other.getFirstOccurrence()){ 
        return 1; 
       } 
       else{ 
        return -1; 
       } 
      } 
     } 

     public String getLocationName(){ 
      if(theLocation instanceof File){ 
       return ((File) theLocation).getAbsolutePath(); 
      } 
      else{ 
       return theLocation.toString(); 
      } 
     } 

     public Integer getFirstOccurrence(){ 
      return firstOccurrence; 
     } 

     public Integer getOccurrenceCount(){ 
      return this.occurrenceCount; 
     } 

     public void addToOccurrenceCount(Integer toAdd){ 
      occurrenceCount += toAdd; 
     } 

     public void setFirstOccurrence(Integer firstOcc){ 
      firstOccurrence = new Integer(firstOcc); 
     } 
    } 

Answer 1

你的代码，因为你展示它，会产生你给是正确的，而不是你要求它做的不正确输出的输出。

下面是一个自包含演示：

https://gist.github.com/4056538