java 中的比较器(Comparator)

最新推荐文章于 2023-02-18 18:31:58 发布

最新推荐文章于 2023-02-18 18:31:58 发布 · 176 阅读

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本文介绍了Java中使用数组和比较器对Person类对象进行排序的过程，包括自定义比较器类的实现和匿名内部类的使用。展示了如何通过比较器实现对象的排序逻辑。

import java.util.Arrays; import java.util.Comparator; class Person { private String name; private int age; public Person(String name, int age) { this.name = name; this.age = age; } public String getName() { return this.name; } public int getAge() { return this.age; } @Override public String toString() { // TODO Auto-generated method stub return ""+this.name+" "+this.age; } } class Cmp implements Comparator { @Override public int compare(Object arg0, Object arg1) { Person a = (Person) arg0; Person b = (Person) arg1; if (a.getName().compareTo(b.getName()) != 0) return a.getName().compareTo(b.getName()); else { if (a.getAge() < b.getAge()) return -1; else if (a.getAge() > b.getAge()) return 1; else return 0; } } } public class Main { public static void main(String[] args) { Person[] p = new Person[4]; p[0] = new Person("ZZZ",19); p[1] = new Person("AAA", 109); p[2] = new Person("AAA", 19); p[3] = new Person("YYY",100); Arrays.sort(p, new Cmp()); System.out.println(Arrays.toString(p)); } }

当然由于比较器的实现类只用显示实现一个方法，因此，我们可以不用专门写一个类来实现它，当我们需要用到比较器时，可以写个匿名内部类来实现 Comparator

import java.util.Arrays; import java.util.Comparator; class Person { private String name; private int age; public Person(String name, int age) { this.name = name; this.age = age; } public String getName() { return this.name; } public int getAge() { return this.age; } @Override public String toString() { return ""+this.name+" "+this.age; } } public class Main { public static void main(String[] args) { Person[] p = new Person[4]; p[0] = new Person("ZZZ",19); p[1] = new Person("AAA", 109); p[2] = new Person("AAA", 19); p[3] = new Person("YYY",100); Arrays.sort(p, new Comparator<Object>() { @Override public int compare(Object arg0, Object arg1) { Person a = (Person) arg0; Person b = (Person) arg1; if (a.getName().compareTo(b.getName()) != 0) return a.getName().compareTo(b.getName()); else { if (a.getAge() < b.getAge()) return -1; else if (a.getAge() > b.getAge()) return 1; else return 0; } } }); System.out.println(Arrays.toString(p)); } }

之前一直用的是 Comparable接口，下午把比较器学了下