我可以在不实施Comparable的情况下使用比较器吗？ [英] Can I use a Comparator without implementing Comparable?

问题描述

是否可以在不实现Comparable类的情况下使用Comparator？例如，如果我有以下内容：

Is it possible to use a Comparator without implementing the Comparable class? For instance, if I had the following:

MyClass {

     Comparator comp;

     OrderedListInheritance(Comparator c) {
          this.comp = c;
     }

}

我可以用comp比较两个物体？如果是这样，我将如何去做？

Could I then use comp to compare two objects? If so, how would I go about doing that?

谢谢...

推荐答案

您不使用< a href = http://www.j2ee.me/javase/6/docs/api/java/lang/Comparable.html rel = noreferrer> 可比较 。您使用 比较器 。

You don't use Comparable. You use Comparator.

可比较是由对象实现的接口，用于指定它们与其他对象的排序顺序相同类型的对象。

Comparable is an interface implemented by objects to specify their sort order with other objects of the same type.

比较器是一个通用接口，它仅接受两个对象并告诉您它们的排序顺序。因此，您可以这样做：

Comparator is a generic interface that simply takes two objects and tells you their sort order. So you can do:

public class Student {
  private final int id;
  private final String name;
  private final int age; 

  public Student(int id, String name, int age) {
    this.id = id;
    this.name = name;
    this.age = age;
  }

  public int getId() { return id; }
  public String getName() { return name; }
  public int getAge() { return age; }
}

其中：

public class AgeComparator implements Comparator<Student> {
  public int compare(Student s1, Student s2) {
    if (s1.getAge() == s2.getAge()) {
      return 0;
    } else {
      return s1.getAge() < s2.getAge() ? -1 : 1;
  }
}

和：

List<Student> students = new ArrayList<Student>();
students.add(new Student(1, "bob", 15));
students.add(new Student(2, "Jane", 14));
students.add(new Student(3, "Gary", 16));

SortedSet<Student> set1 = new TreeSet<Student>(new AgeComparator());
set1.addAll(students);
for (Student student : set1) {
  // age order
}

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