Java://Comparator、Comparable的用法(按照要求将set集合的数据进行排序输出):

时间:2021-12-10 11:45:09
import java.util.ArrayList;

import java.util.Collections;

import java.util.Comparator;

//comparator、comparable的用法(按照要求将map集合的键值对进行顺序输出)

import java.util.List;

public class Test

{

   public static <T> void sop(T t)

   {

    System.out.println(t);

   }

   public static void main(String args[]) throws Exception

   {

    // 创建一个map集合,用来存储数据 <>表示接收的是泛型,即指定的类型

    List<Person> list = new ArrayList<Person>();

    // 往集合添加数据

    list.add(new Person("czhangsan1", "11", "beijing"));

    list.add(new Person("zhangsan5", "15", "nanjing"));

    list.add(new Person("azhangsan5", "10", "shanghai"));

    list.add(new Person("zhangsan2", "20", "haierbing"));

    list.add(new Person("bzhangsan2", "20", "beijing"));

    list.add(new Person("zhangsan3", "12", "shanghai"));

    list.add(new Person("zhangsan4", "19", "changchun"));

    list.add(new Person("zhangsan4", "10", "changchun"));

    list.add(new Person("zhangsan4", "10", "zhengzhou"));

    // 将map集合转换为set集合,因为map集合没有迭代器 ,而set集合有

    Collections.sort(list);

    System.out.println("按年龄排序:");

    for (Person person : list)

    {

    System.out.println(person.toString());

    }

    Collections.sort(list, new MyCompare());

    System.out.println("按姓名排序:");

    for (Person person : list)

    {

        System.out.println(person.toString());

    }

  }

}

class Person implements Comparable<Person>// 使Person的属性具有比较性

{

   private String name;

   private String age;

   private String address;

   public Person(String name, String age, String address)// 初始化

   {

    this.name = name;

    this.age = age;

    this.address = address;

   }

   public String getName()

   {

    return name;

   }

   public void setName(String name)

   {

    this.name = name;

   }

   public String getAge()

   {

    return age;

   }

   public void setAge(String age)

   {

    this.age = age;

   }

   public String getAddress()

   {

    return address;

   }

   public void setAddress(String address)

   {

    this.address = address;

   }

   @Override

   public String toString() 

   {

    return "姓名:" + name + ", 年龄:" + age + ", 地址:" + address;

   }

   // 按年龄大小排序规则

   @Override

   public int compareTo(Person o)

   {

    return this.age.compareTo(o.getAge());

   }

}

// 按姓名字典顺序排序

class MyCompare implements Comparator<Person>// 自定义一个比较器

{

   @Override

   public int compare(Person o1, Person o2)

   {

    return o1.getName().compareTo(o2.getName());

   }

}

// 注意:上面的两种形式都实现了比较,任选其中一种就可以。要么实现comparable接口;要么在集合中传入自定义的比较器。