Cirry's Blog

比较器的引出Comparable

范例：实现自定义对象数组排序操作

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package cn.cccc.demo;
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import java.util.Arrays;
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public class Demo {
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    public static void main(String[] args) {
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       Person data [] = new Person [] {
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               new Person("cc",20),
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               new Person("ww",18)
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       };
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       Arrays.sort(data);
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       System.out.println(Arrays.toString(data));
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    }
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}
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class Person implements Comparable<Person>{
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    private String name;
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    private int age;
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    public Person(String name , int age){
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       this.name = name;
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       this.age = age;
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    }
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    public String toString(){
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       return "[个人信息]姓名"+this.name+"年龄："+this.age;
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    }
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    @Override
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    public int compareTo(Person per) {
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       // TODO Auto-generated method stub
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       return per.age-this.age;
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    }
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}

Comparator比较器

是一种挽救类的比较器，其主要的目的是解决一些没有使用Comparabnle排序的类的对象数组排序。范例：现在项目已经开发完成了，并且由于先期的设计并没有去考虑到所为的比较器功能。范例：

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package cn.cccc.demo;
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import java.util.Arrays;
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public class Demo {
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    public static void main(String[] args) {
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       Person data [] = new Person [] {
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               new Person("cc",20),
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               new Person("ww",18)
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       };
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    }
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}
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class Person{
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    private String name;
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    private int age;
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    public Person(String name , int age){
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       this.name = name;
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       this.age = age;
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    }
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    public String toString(){
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       return "[个人信息]姓名"+this.name+"年龄："+this.age;
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    }
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}

后来经过若干个版本的迭代更新只有发现需要对Person类进行排序处理，但是又不能够去使用Comparable接口，所以这个时候就需要采用一种挽救的形式来实现比较。范例：实现自定义规则排序

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package cn.cccc.demo;
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import java.util.Arrays;
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import java.util.Comparator;
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public class Demo {
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    public static void main(String[] args) {
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       Person data [] = new Person [] {
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               new Person("cc",20),
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               new Person("ww",18)
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       };
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       Arrays.sort(data, new  PersonComparator());
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       System.out.println(Arrays.toString(data));
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    }
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}
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class Person{
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    private String name;
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    private int age;
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    public Person(String name , int age){
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       this.name = name;
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       this.age = age;
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    }
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    public String getName() {
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       return name;
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    }
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    public void setName(String name) {
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       this.name = name;
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    }
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    public int getAge() {
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       return age;
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    }
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    public void setAge(int age) {
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       this.age = age;
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    }
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    public String toString(){
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       return "[个人信息]姓名"+this.name+"年龄："+this.age;
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    }
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}
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class PersonComparator implements  Comparator<Person>{
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    @Override
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    public int compare(Person o1, Person o2)  {
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       return o1.getAge() -o2.getAge();
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    }
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}