Java sort集合排序的两种方式解析

这篇文章主要介绍了Java sort集合排序的两种方式解析,文中通过示例代码介绍的非常详细，对大家的学习或者工作具有一定的参考学习价值,需要的朋友可以参考下

Comparable和Comparator

public static  void sort(List list); 将集合中的数据按照默认规则进行排序 (我们在自己的类里面实现Comparabl接口方法compareTo)
public static  void sort(List list, Comparator); 将集合中的数据按照指定规则进行排序

Comparable

public class Demo02Sort {
  public static void main(String[] args) {
    ArrayList objects = new ArrayList<>();
    objects.add(new Person("小明", 23));
    objects.add(new Person("小红", 24));
    objects.add(new Person("小绿", 22));

    System.out.println("objects = " + objects);
    Collections.sort(objects);
    System.out.println("objects = " + objects);
  }
}


class Person implements Comparable {
  private String name;
  private int age;

  @Override
  public int compareTo(Person person) {
//    return 0;
    return this.getAge() - person.getAge();

  }

  @Override
  public String toString() {
    return "Person{" +
 "name='" + name + ''' +
 ", age=" + age +
 '}';
  }

  public Person() {
  }

  public Person(String name, int age) {
    this.name = name;
    this.age = age;
  }

  public String getName() {
    return name;
  }

  public void setName(String name) {
    this.name = name;
  }

  public int getAge() {
    return age;
  }

  public void setAge(int age) {
    this.age = age;
  }
}

Comparator

public class Demo03SortComparator {
  public static void main(String[] args) {
    ArrayList objects = new ArrayList<>();
    objects.add(new Person1("b小明", 23));
    objects.add(new Person1("小红", 24));
    objects.add(new Person1("小绿", 22));
    objects.add(new Person1("a小绿", 23));

    System.out.println("objects = " + objects);
    Collections.sort(objects, new Comparator() {
      @Override
      public int compare(Person1 person1, Person1 t1) {
// return 0;
 int res = person1.getAge() - t1.getAge();

 // 前面减去后面,升序排列
 if (res == 0) {
   return person1.getName().charAt(0) - t1.getName().charAt(0);
 }
 return res;
      }
    });
    System.out.println("objects = " + objects);
  }
}


class Person1 {
  private String name;
  private int age;


  @Override
  public String toString() {
    return "Person{" +
 "name='" + name + ''' +
 ", age=" + age +
 '}';
  }

  public Person1() {
  }

  public Person1(String name, int age) {
    this.name = name;
    this.age = age;
  }

  public String getName() {
    return name;
  }

  public void setName(String name) {
    this.name = name;
  }

  public int getAge() {
    return age;
  }

  public void setAge(int age) {
    this.age = age;
  }
}

* Comparable: 我们的类继承Comparable接口,然后实现里面的CompareTo方法,
 *如何调用:Collections.sort(arrayList)
 *
 * Comparator: 我们的类不用继承Comparable接口,也不用继承Comparator接口
 *如何调用:Collections.sort(objects, new Comparator() { // 匿名类
     @Override
     public int compare(Person1 person1, Person1 t1) {
int res = person1.getAge() - t1.getAge();
// 前面减去后面,升序排列
if (res == 0) {
  return person1.getName().charAt(0) - t1.getName().charAt(0);
}
return res;
     }
   });

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