Java中实现Comparable和Comparator对象比较

import java.util.Comparator;
import java.util.LinkedList;
class Person{
  private float height;
  private String name;
  
  Person(float height)
  {
    this.height=height;
  }
  public float getHeight() {
    return height;
  }
  public void setHeight(float height) {
    this.height = height;
  }
  public String getName() {
    return name;
  }
  public void setName(String name) {
    this.name = name;
  }
}
class PersonHeight implements Comparator<Person>{
   
  @Override
  //重写compare方法，return<0不变，return>0则交换顺序（保持升序）
  public int compare(Person e1, Person e2) {
    if(e1.getHeight() < e2.getHeight()){
      return 1;
    } else {
      return -1;
    }
  }
}
public class Question3 {
  public static void main(String[] args) {
    Person p1=new Person(23.4f);
    p1.setName("Stud1");
    Person p2=new Person(2.34f);
    p2.setName("Stud2");
    Person p3=new Person(34.32f);
    p3.setName("Stud3");
    Person p4=new Person(56.45f);
    p4.setName("Stud4");
    Person p5=new Person(21.4f);
    p5.setName("Stud5");
    
    LinkedList<Person> al=new LinkedList<Person>();
    al.add(p1);
    al.add(p2);
    al.add(p3);
    al.add(p4);
    al.add(p5);
    
        //调用sort方法，实现排序
    Collections.sort(al, new PersonHeight());
    
        //遍历输出
    for(Person p:al)
      System.out.println(p.getName());
  }
}

//对日期进行排序
/**
 * 如果o1小于o2,返回一个负数;如果o1大于o2，返回一个正数;如果他们相等，则返回0;
 */
@Override
public int compare(Step o1, Step o2) {
  Date acceptTime1=UtilTool.strToDate(o1.getAcceptTime(), null);
  Date acceptTime2=UtilTool.strToDate(o2.getAcceptTime(), null);
  
  //对日期字段进行升序，如果欲降序可采用before方法
  if(acceptTime1.after(acceptTime2)) return 1;
  return -1;
}

import java.util.Collections;
import java.util.Comparator;
import java.util.LinkedList;
class Person implements Comparable{
  private float height;
  private String name;
  
  Person(float height)
  {
    this.height=height;
  }
  public float getHeight() {
    return height;
  }
  public void setHeight(float height) {
    this.height = height;
  }
  public String getName() {
    return name;
  }
  public void setName(String name) {
    this.name = name;
  }
  @Override
  public int compareTo(Object o) {
    // TODO Auto-generated method stub
    if(this.height>((Person)o).height){
      return 1;
    }else
    return -1;
  }
  
}
public class Question3 {
  public static void main(String[] args) {
    Person p1=new Person(23.4f);
    p1.setName("Stud1");
    Person p2=new Person(2.34f);
    p2.setName("Stud2");
    Person p3=new Person(34.32f);
    p3.setName("Stud3");
    Person p4=new Person(56.45f);
    p4.setName("Stud4");
    Person p5=new Person(21.4f);
    p5.setName("Stud5");
    
    LinkedList<Person> al=new LinkedList<Person>();
    al.add(p1);
    al.add(p2);
    al.add(p3);
    al.add(p4);
    al.add(p5);
    
    Collections.sort(al);
    
    for(Person p:al)
      System.out.println(p.getName());
  }
}