我有一个像这样的数据集：85 [Italy, France] 95 [Italy]91 [Israel, Jordan]85 [France, Italy, Switzerland]80 [USA]84 [Mongolia, China]95 [Antarctica]84 [African Union]82 [Argentina]95 [Tibet, Nepal]...我使用下面的代码（定义类模型）基于整数进行了排序：public class Wonder implements Comparable<Wonder> { int hostility; List<String> countries; //some other data members //constructor //getters @Override public int compareTo(Wonder other) { if(hostility == other.hostility) { return 0; } else if(hostility < other.hostility) { return -1; } else if(hostility > other.hostility) { return 1; } else { return 0; } }}排序代码（PS：getAllData方法将返回奇迹列表，从文本文件加载）：List<Wonder> wonders = getAllData(filePath);wonders.sort((c1,c2)->c1.compareTo(c2));Collections.reverse(wonders); // ordering highest to lowest 排序后的数据集（基于整数排序）看起来像这样：95 [Antarctica]95 [Italy]95 [Tibet, Nepal]91 [Israel, Jordan]85 [France, Italy, Switzerland]85 [Italy, France]84 [Mongolia, China]84 [African Union]82 [Argentina]80 [USA]...现在，需要将新生成的数据集按字母顺序排序，即国家列表（字符串）。例如，在新数据集中，有两条记录具有相同的整数 84（第一个整数为蒙古国，第二个整数为非洲联盟国家），因此第二条记录应该排在第一位，因为非洲联盟按字母顺序排列在蒙古之前。...84 [African Union]84 [Mongolia, China]...问题：如何根据字符串列表对整数列表进行排序？
3 回答
慕标5832272
TA贡献1966条经验 获得超4个赞
您可以进一步专门化 compareTo 函数以进行二次比较。我假设每个列表至少包含一个国家；如果不是这种情况，您必须处理空列表。改变后的 compareTo 是这样的：
@Override
public int compareTo(Wonder other) {
if(this == other) {
return 0;
} else if(hostility < other.hostility) {
return -1;
} else if(hostility > other.hostility) {
return 1;
} else {
return -countries.get(0).compareTo(other.countries.get(0));
}
}
或者你可能正在寻找这个：
wonders.sort(Comparator.comparingInt(Wonder::getHostility).reversed()
.thenComparing(wonder -> wonder.getCountries().get(0)));
//don't reverse afterwards!
白衣染霜花
TA贡献1796条经验 获得超10个赞
如果你这样做，接受的答案建议：
wonders.sort(Comparator.comparingInt(Wonder::getHostility).reversed()
.thenComparing(wonder -> wonder.getCountries().get(0)));
在您提供的文本文件上，您将获得下一个结果：
95 [Antarctica]
95 [Italy]
95 [Tibet, Nepal]
91 [Israel, Jordan]
85 [France, Italy, Switzerland]
85 [Italy, France]
84 [African Union]
84 [Mongolia, China]
82 [Argentina]
80 [USA]
70 [Australia]
69 [Japan]
69 [USA, Canada]
65 [The Hawaiian Islands]
65 [USA]
55 [Russia]
50 [Brazil, Argentina]
19 [Tanzania]
17 [Northern Ireland]
16 [China]
12 [African Union]
10 [Australia]
10 [Brazil]
2 [USA]
但是，如果您先排序countries然后接受答案：
wonders.forEach(wonder -> Collections.sort(wonder.getCountries()));
wonders.sort(Comparator.comparingInt(Wonder::getHostility).reversed().
thenComparing(wonder -> wonder.getCountries().get(0)));
然后你会得到：
95 [Antarctica]
95 [Italy]
95 [Nepal, Tibet]
91 [Israel, Jordan]
85 [France, Italy]
85 [France, Italy, Switzerland]
84 [African Union]
84 [China, Mongolia]
82 [Argentina]
80 [USA]
70 [Australia]
69 [Canada, USA]
69 [Japan]
65 [The Hawaiian Islands]
65 [USA]
55 [Russia]
50 [Argentina, Brazil]
19 [Tanzania]
17 [Northern Ireland]
16 [China]
12 [African Union]
10 [Australia]
10 [Brazil]
2 [USA]
注意这两个列表中的hostility值85和值69。顺序不一样。不知道这是否与您有关。
PS 如果你实施Comparable#compareTo()，你也应该实施，equals()因为它们之间有合同：
(x.compareTo(y) == 0) == (x.equals(y))
如果不是这种情况，您应该注意：This class has a natural ordering that is inconsistent with equals.
最后一件事：
compareTo()NullPointerException如果当前对象与对象进行比较，null而不是在这种情况下equals()返回，则必须抛出。false
冉冉说
TA贡献1877条经验 获得超1个赞
不确定我明白你的问题是什么。下面的伪代码能解决您的问题吗？
@Override
public int compareTo(Wonder other) {
if(hostility == other.hostility) {
// let's compare the strings list when hostility integer are equals (84, 84)
String firstOtherCountry = other.countries.SortAlphabetically().get(0);
// we sort the countries list for current line and other wonder
// you compare alphabetically first element of each list :
// return 1, 0 or -1 here.
} else if(hostility < other.hostility) {
return -1;
} else if(hostility > other.hostility) {
return 1;
} else {
return 0;
}
}
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