集合排序 Comparator和Comparable的使用区别

Java 排序 Compare 
 
Comparator接口
Comparable接口
区别
 
在Java中使用集合来存储数据时非常常见的,集合排序功能也是常用功能之一.下面看一下如何进行集合排序,常用的方法有: Comparator和Comparable

  
Comparator接口使用步骤:
新建比较类,
实现Comparator接口,
重写compare方法,
package sort; 
 
import java.util.Comparator; 
 
public class LuckBoyCompare implements Comparator<LuckBoy>{ 
 
    @Override 
    public int compare(LuckBoy o1, LuckBoy o2) { 
        return o1.getAge()-o2.getAge(); 
    } 
 
} 
 
调用Collections.sort()方法进行排序,
形式:Collections.sort(集合, 比较器实例).
@Test 
public void test1() { 
    List<LuckBoy> boyList = new ArrayList<LuckBoy>(); 
    LuckBoy boy1 = new LuckBoy("张三",13,"上海"); 
    LuckBoy boy2 = new LuckBoy("李四",12,"北京"); 
    LuckBoy boy3 = new LuckBoy("王五",18,"深圳"); 
    LuckBoy boy4 = new LuckBoy("马六",17,"南京"); 
 
    boyList.add(boy1); 
    boyList.add(boy2); 
    boyList.add(boy3); 
    boyList.add(boy4); 
 
    System.out.println("排序前:"); 
    for (LuckBoy luckBoy : boyList) { 
        System.out.println(luckBoy); 
    } 
 
    System.out.println("排序后:"); 
    Collections.sort(boyList, new LuckBoyCompare()); 
    for (LuckBoy luckBoy : boyList) { 
        System.out.println(luckBoy); 
    } 
} 
LuckBoy.java
package sort; 
 
public class LuckBoy{ 
    private String name; 
    private Integer age; 
    private String city; 
 
    public LuckBoy() { 
        super(); 
    } 
 
    public LuckBoy(String name, Integer age, String city) { 
        super(); 
        this.name = name; 
        this.age = age; 
        this.city = city; 
    } 
 
    public String getName() { 
        return name; 
    } 
    public void setName(String name) { 
        this.name = name; 
    } 
    public Integer getAge() { 
        return age; 
    } 
    public void setAge(Integer age) { 
        this.age = age; 
    } 
    public String getCity() { 
        return city; 
    } 
    public void setCity(String city) { 
        this.city = city; 
    } 
 
    @Override 
    public String toString() { 
        return "LuckBoy [name=" + name + ", age=" + age + ", city=" + city + "]"; 
    } 
} 
打印结果:
排序前:
LuckBoy [name=张三, age=13, city=上海]
LuckBoy [name=李四, age=12, city=北京]
LuckBoy [name=王五, age=18, city=深圳]
LuckBoy [name=马六, age=17, city=南京]
排序后:
LuckBoy [name=李四, age=12, city=北京]
LuckBoy [name=张三, age=13, city=上海]
LuckBoy [name=马六, age=17, city=南京]
LuckBoy [name=王五, age=18, city=深圳]

  
Comparable接口使用步骤:
数据模型实现Comparable接口,
重写compareTo方法,
package sort; 
 
public class LuckBoy implements Comparable<LuckBoy>{ 
//TODO 中间代码省略 
    @Override 
    public int compareTo(LuckBoy o) { 
        return this.age-o.age; 
    } 
} 
 
调用Collections.sort()方法进行排序,
形式:Collections.sort(集合)
@Test 
public void test2() { 
    List<LuckBoy> boyList = new ArrayList<LuckBoy>(); 
    LuckBoy boy1 = new LuckBoy("张三",13,"上海"); 
    LuckBoy boy2 = new LuckBoy("李四",12,"北京"); 
    LuckBoy boy3 = new LuckBoy("王五",18,"深圳"); 
    LuckBoy boy4 = new LuckBoy("马六",17,"南京"); 
 
    boyList.add(boy1); 
    boyList.add(boy2); 
    boyList.add(boy3); 
 
    boyList.add(boy4); 
 
    System.out.println("============================"); 
    System.out.println("排序前:"); 
    for (LuckBoy luckBoy : boyList) { 
        System.out.println(luckBoy); 
    } 
 
    System.out.println("排序后:"); 
    Collections.sort(boyList); 
    for (LuckBoy luckBoy : boyList) { 
        System.out.println(luckBoy); 
    } 
} 
打印结果:
排序前:
LuckBoy [name=张三, age=13, city=上海]
LuckBoy [name=李四, age=12, city=北京]
LuckBoy [name=王五, age=18, city=深圳]
LuckBoy [name=马六, age=17, city=南京]
排序后:
LuckBoy [name=李四, age=12, city=北京]
LuckBoy [name=张三, age=13, city=上海]
LuckBoy [name=马六, age=17, city=南京]
LuckBoy [name=王五, age=18, city=深圳]

  
区别Comparator 使用灵活,不需要修改源码.但是,使用时需要传入比较器对象;

Comparable 使用简单,但是需要修改源码.
作者：林宇风
出处：https://www.cnblogs.com/linyufeng/