Java：使用Collat​​orKey对集合进行排序 [英] Java: Sort a Collection using a CollatorKey

问题描述

我想要实现的是通过字符串值对对象的集合进行排序。但是，使用collat​​or以依赖于语言环境的方式。由于性能原因，我不想使用Collat​​or compare（）方法（如下面的代码中）而不是Collat​​ionKey类，因为java API声明使用Collat​​ionKey要快得多。

但是如何使用Collat​​ionKey实现compareTo（）方法？据我所知，如果我要使用Collat​​ionKey，我必须自己完全编写所有的比较方法。所以我甚至不再能够使用Collections.sort（）方法......我非常感谢一个易于理解的示例，以及使用Collat​​ionKey对Person对象集合进行排序的最有效实现。 / p>

谢谢！

  public class Person实现Comparable< Person> {
 
 String lastname; 
 
 public int compareTo（Person person）{
 //这可行，但它不是表现良好的最佳实现
 Collat​​or instance = Collat​​or.getInstance（Locale.ITALY） ; 
 return instance.compare（lastname，person.lastname）; 
} 
} 
 
 ... 
 ArrayList list = new ArrayList（）; 
人员1 =新人（foo）; 
 list.add（person1）; 
人员2 =新人（酒吧）; 
 list.add（person2）; 
 Collections.sort（list）; 
 ... 
  

解决方案

  class Person实现Comparable< Person> {
 
 private static final Collat​​or collat​​or = Collat​​or.getInstance（Locale.ITALY）; 
 
 private final String lastname; 
 
私人最终Collat​​ionKey键; 
 
 Person（String lastname）{
 this.lastname = lastname; 
 this.key = collat​​or.getCollat​​ionKey（lastname）; 
} 
 
 public int compareTo（Person person）{
 return key.compareTo（person.key）; 
} 
 
} 
  

what I would like to achieve is to sort a colletion of objects by a string value. However in a locale dependant way using a collator. Due to performance reasons I do not want to use the Collator compare() method (as below in the code) rather the CollationKey class, as the java API states the using a CollationKey is much faster.

But how do I implement the compareTo() method using the CollationKey? As far as I understood it, I have to completely write all the comparison Methods on my own if I will be using a CollationKey. So I will even no longer be able to use the Collections.sort() methods... I am very thankfull for an example that is easy to understand and a the most efficient implementation to sort the Collection of Person objects using a CollationKey.

Thank you!

public class Person implements Comparable<Person> {

String lastname;

public int compareTo(Person person) {
     //This works but it is not the best implementation for a good performance
     Collator instance = Collator.getInstance(Locale.ITALY);
     return instance.compare(lastname, person.lastname);
}
}

...
ArrayList list = new ArrayList();
Person person1 = new Person("foo");
list.add(person1);
Person person2 = new Person("bar");
list.add(person2);
Collections.sort(list);
...

解决方案

class Person implements Comparable<Person> {

  private static final Collator collator = Collator.getInstance(Locale.ITALY);

  private final String lastname;

  private final CollationKey key;

  Person(String lastname) {
    this.lastname = lastname;
    this.key = collator.getCollationKey(lastname);
  }

  public int compareTo(Person person) {
     return key.compareTo(person.key);
  }

}

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