List集合排序实体类实现Comparator接口和实现Comparable接口排序

1. package com.collection;
   
   import java.util.ArrayList;
   import java.util.Collections;
   import java.util.Comparator;
   import java.util.List;
   
   /**
    * 容器排序
    * @author 26920
    *
    */
   public class TestList {
   	public static void main(String[] args) {
   		List list=new ArrayList();
   		list.add(new Student());
   		list.add(new Student("wangwu",20,90));
   		list.add(new Student("lisi",17,80));
   		list.add(new Student("zhangliu",18,60));
   		list.add(new Student("wangba",15,70));
   		for (Student student : list) {
   			System.out.println(student.toString());
   		}
   		System.out.println("排序后===========================");
   		Collections.sort(list, new Student());
   		//list.sort(new Student());等价于Collections.sort(list, new Student());
   		for (Student student : list) {
   			System.out.println(student.toString());
   		}
   	}
   }
   class Student implements Comparator{
   	private String name;
   	private int age;
   	private double grade;
   	public Student(String name, int age, double grade) {
   		super();
   		this.name = name;
   		this.age = age;
   		this.grade = grade;
   	}
   	public Student() {
   		this("zhangsan",18,100);
   	}
   	@Override
   	public int compare(Student o1, Student o2) {
   		// TODO Auto-generated method stub
   		int num=o1.age-o2.age;
   		if(num==0){
   			num=(int) (o1.grade-o2.grade);
   		}
   		return num;
   	}
   	@Override
   	public String toString() {
   		return "Student [name=" + name + ", age=" + age + ", grade=" + grade + "]";
   	}
   	
   }
   

    

2. 输出结果

   Student [name=zhangsan, age=18, grade=100.0]
   Student [name=wangwu, age=20, grade=90.0]
   Student [name=lisi, age=17, grade=80.0]
   Student [name=zhangliu, age=18, grade=60.0]
   Student [name=wangba, age=15, grade=70.0]
   排序后===========================
   Student [name=wangba, age=15, grade=70.0]
   Student [name=lisi, age=17, grade=80.0]
   Student [name=zhangliu, age=18, grade=60.0]
   Student [name=zhangsan, age=18, grade=100.0]
   Student [name=wangwu, age=20, grade=90.0]
   

    

3. 实现Comparable接口排序

   package com.collection;
   
   import java.util.ArrayList;
   import java.util.Collections;
   import java.util.List;
   
   /**
    * list排序规则2
    * @author 26920
    *
    */
   public class TestList02 {
   	public static void main(String[] args) {
   		Listlist=new ArrayList();
   		list.add(new Teacher(24,"nan","zhangsan",4500));
   		list.add(new Teacher(25,"nan","wangba",5000));
   		list.add(new Teacher(26,"nan","zhangliu",5500));
   		list.add(new Teacher(27,"nan","lisi",7500));
   		list.add(new Teacher(25,"nan","wangwu",5000));
   		for (Teacher teacher : list) {
   			System.out.println(teacher.toString());
   		}
   		Collections.sort(list);
   		System.out.println("排序后===========================");
   		for (Teacher teacher : list) {
   			System.out.println(teacher.toString());
   		}
   	}
   }
   class Teacher implements Comparable{
   	private int age;
   	private String sex;
   	private String name;
   	private double salary;
   	@Override
   	public int compareTo(Teacher o) {
   		int num=this.age-o.age;
   		if(num==0){
   			num=(int) (this.salary-o.salary);
   		}
   		return num;
   	}
   	public Teacher(int age, String sex, String name, double salary) {
   		super();
   		this.age = age;
   		this.sex = sex;
   		this.name = name;
   		this.salary = salary;
   	}
   	public Teacher() {
   		super();
   		// TODO Auto-generated constructor stub
   	}
   	@Override
   	public String toString() {
   		return "Teacher [age=" + age + ", sex=" + sex + ", name=" + name + ", salary=" + salary + "]";
   	}
   }

    

4. 输出结果

   Teacher [age=24, sex=nan, name=zhangsan, salary=4500.0]
   Teacher [age=25, sex=nan, name=wangba, salary=5000.0]
   Teacher [age=26, sex=nan, name=zhangliu, salary=5500.0]
   Teacher [age=27, sex=nan, name=lisi, salary=7500.0]
   Teacher [age=25, sex=nan, name=wangwu, salary=5000.0]
   排序后===========================
   Teacher [age=24, sex=nan, name=zhangsan, salary=4500.0]
   Teacher [age=25, sex=nan, name=wangba, salary=5000.0]
   Teacher [age=25, sex=nan, name=wangwu, salary=5000.0]
   Teacher [age=26, sex=nan, name=zhangliu, salary=5500.0]
   Teacher [age=27, sex=nan, name=lisi, salary=7500.0]