Java Comparable和Comparator对比详解

public class Students implements Comparable<Students> {

  private String name;
  private int age;
  private String address;

  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;
  }

  public String getAddress() {
    return address;
  }

  public void setAddress(String address) {
    this.address = address;
  }

  @Override
  public String toString() {
    StringBuilder sb = new StringBuilder();
    sb.append("姓名：").append(this.name);
    sb.append("年龄：").append(this.age);
    sb.append("地址：").append(this.address);
    return sb.toString();

  }

  // 重写排序方法，先根据年龄升序，再根据姓名降序，最后根据地址升序
  @Override
  public int compareTo(Students o) {
    int result= 0;
    result = this.age - o.getAge();
    if (0 == result){
      result = o.getName().compareTo(this.getName());
      if (0 == result){
        result = this.getAddress().compareTo(o.getAddress());
      }
    }
    return result;
  }
}

import java.util.*;

public class CompareController1 implements Comparator<Integer> {
  @Override
  public int compare(Integer o1, Integer o2) {
//    int length1 = o1.length();
//    int length2 = o2.length();
    return o2 - o1;  //按照降序排列
  }

  public static void main(String[] args) {
    List<Integer> list = new ArrayList<>();
    list.add(1);
    list.add(23);
    list.add(400);
    list.add(222);
    list.add(34);

    Collections.sort(list,new CompareController1());
    System.out.println(list.toString());

    Object[] objects = list.toArray();
    // 针对String类型，默认是按照字典表进行排序
    // 针对 int 类型，默认是 按照 升序 进行排序
    Arrays.sort(objects);
    //不能直接打印数组，那样打印出来的是地址，可以使用 foreach
    System.out.println(Arrays.toString(objects));

  }
}