集合排序 Comparator和Comparable的使用区别

时间：2021-08-01 11:53:00
Java 排序 Compare 

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:

  1. 新建比较类,
  2. 实现Comparator接口,
  3. 重写compare方法,
  1. package sort; 
  3. import java.util.Comparator; 
  5. public class LuckBoyCompare implements Comparator<LuckBoy>{ 
  7. @Override 
  8. public int compare(LuckBoy o1, LuckBoy o2) { 
  9. return o1.getAge()-o2.getAge(); 
  10. } 
  12. } 
  • 调用Collections.sort()方法进行排序,
  • 形式:Collections.sort(集合, 比较器实例).
  1. @Test 
  2. public void test1() { 
  3. List<LuckBoy> boyList = new ArrayList<LuckBoy>(); 
  4. LuckBoy boy1 = new LuckBoy("张三",13,"上海"); 
  5. LuckBoy boy2 = new LuckBoy("李四",12,"北京"); 
  6. LuckBoy boy3 = new LuckBoy("王五",18,"深圳"); 
  7. LuckBoy boy4 = new LuckBoy("马六",17,"南京"); 
  9. boyList.add(boy1); 
  10. boyList.add(boy2); 
  11. boyList.add(boy3); 
  12. boyList.add(boy4); 
  14. System.out.println("排序前:"); 
  15. for (LuckBoy luckBoy : boyList) { 
  16. System.out.println(luckBoy); 
  17. } 
  19. System.out.println("排序后:"); 
  20. Collections.sort(boyList, new LuckBoyCompare()); 
  21. for (LuckBoy luckBoy : boyList) { 
  22. System.out.println(luckBoy); 
  23. } 
  24. } 

LuckBoy.java

  1. package sort; 
  3. public class LuckBoy{ 
  4. private String name; 
  5. private Integer age; 
  6. private String city; 
  8. public LuckBoy() { 
  9. super(); 
  10. } 
  12. public LuckBoy(String name, Integer age, String city) { 
  13. super(); 
  14. this.name = name; 
  15. this.age = age; 
  16. this.city = city; 
  17. } 
  19. public String getName() { 
  20. return name; 
  21. } 
  22. public void setName(String name) { 
  23. this.name = name; 
  24. } 
  25. public Integer getAge() { 
  26. return age; 
  27. } 
  28. public void setAge(Integer age) { 
  29. this.age = age; 
  30. } 
  31. public String getCity() { 
  32. return city; 
  33. } 
  34. public void setCity(String city) { 
  35. this.city = city; 
  36. } 
  38. @Override 
  39. public String toString() { 
  40. return "LuckBoy [name=" + name + ", age=" + age + ", city=" + city + "]"; 
  41. } 
  42. } 

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,
  1. package sort; 
  3. public class LuckBoy implements Comparable<LuckBoy>{ 
  4. //TODO 中间代码省略 
  5. @Override 
  6. public int compareTo(LuckBoy o) { 
  7. return this.age-o.age; 
  8. } 
  9. } 
  • 调用Collections.sort()方法进行排序,
  • 形式:Collections.sort(集合)
  1. @Test 
  2. public void test2() { 
  3. List<LuckBoy> boyList = new ArrayList<LuckBoy>(); 
  4. LuckBoy boy1 = new LuckBoy("张三",13,"上海"); 
  5. LuckBoy boy2 = new LuckBoy("李四",12,"北京"); 
  6. LuckBoy boy3 = new LuckBoy("王五",18,"深圳"); 
  7. LuckBoy boy4 = new LuckBoy("马六",17,"南京"); 
  9. boyList.add(boy1); 
  10. boyList.add(boy2); 
  11. boyList.add(boy3); 
  13. boyList.add(boy4); 
  15. System.out.println("============================"); 
  16. System.out.println("排序前:"); 
  17. for (LuckBoy luckBoy : boyList) { 
  18. System.out.println(luckBoy); 
  19. } 
  21. System.out.println("排序后:"); 
  22. Collections.sort(boyList); 
  23. for (LuckBoy luckBoy : boyList) { 
  24. System.out.println(luckBoy); 
  25. } 
  26. } 

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.

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