接口排序法

创建两个类student类，和Demo1类

import java.text.SimpleDateFormat;
import java.util.Date;

public class Student{
	private int id;
	private String name;
	private Date birthday;
	public Student() {
		super();
		// TODO Auto-generated constructor stub
	}
	public Student(int id, String name, Date birthday) {
		super();
		this.id = id;
		this.name = name;
		this.birthday = birthday;
	}
	public int getId() {
		return id;
	}
	public void setId(int id) {
		this.id = id;
	}
	public String getName() {
		return name;
	}
	public void setName(String name) {
		this.name = name;
	}
	public Date getBirthday() {
		return birthday;
	}
	public void setBirthday(Date birthday) {
		this.birthday = birthday;
	}
	@Override
	public String toString() {
		SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd");
		return  id + ", " + name + "," + sdf.format(birthday);
	}
	
}

package 接口排序;

import java.text.ParseException;
import java.text.SimpleDateFormat;
import java.util.Arrays;
import java.util.Comparator;
import java.util.Date;


public class Demo1 {
	//整数数组排序
	public static void testSort1() {
		int[] arr = {10,23,3,25,4};		
		Arrays.sort(arr);
		for (int i : arr) {
			System.out.print("\t"+i);
		}
	}
	static Student[] s161 = new Student[5];
	//初始化数组
	static void init() throws ParseException {
		SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd");
		Student zhang = new Student(31,"zhangsan", sdf.parse("2000-10-5"));
		Student li = new Student(22,"lisi", sdf.parse("2001-4-25"));
		Student wang = new Student(73,"wangwu", sdf.parse("1999-12-15"));
		Student zhao = new Student(14,"zhaoliu", sdf.parse("2001-8-10"));
		Student tian = new Student(25,"tianqi", sdf.parse("2001-1-5"));
		s161[0] = zhang;
		s161[1] = li;
		s161[2] = wang;
		s161[3] = zhao;
		s161[4] = tian;
	}
	//显示
	static void show() {
		for(Student stu : s161) {
			System.out.println(stu);
		}
	}
	
	//按年龄 
	static void sortByAge() {
		Arrays.sort(s161,new Comparator<Student>() {
			@Override
			public int compare(Student o1, Student o2) {
				long d1 = o1.getBirthday().getTime();
				long d2 = o2.getBirthday().getTime();				
				if(d1>d2)
					return -1;
				else if(d1==d2)
					return 0;
				else
					return 1;
					
			}
		});
	}
	
	//按姓名排序
	static void sortByName() {
		Arrays.sort(s161,new Comparator<Student>() {
			@Override
			public int compare(Student o1, Student o2) {
				String name1= o1.getName();
				String name2 = o2.getName();				
				return name1.compareTo(name2);
			}
		});
	}
	//按学号排序
	static void sortById() {
		//Arrays.sort(t[] arr, Comparator c)
		//Comparator,比较器的接口，
		//有一个唯一的抽象方法: int compare(T o1, T o2)
		//  o1,o2是进行比较的对象，如果o1>o2 返回正数， o1==o2返回0，否则返回负数
		//定义一个对象比较大小的规则 		
		Arrays.sort(s161, new Comparator<Student>() {
			@Override
			public int compare(Student o1, Student o2) {
				//按学号比大小
				return o1.getId()-o2.getId();

			}			
		});	
		Arrays.sort(s161,(o1,o2)-> o1.getId()-o2.getId());//Lanmada优雅方法
	}

	//排序
	public static void main(String[] args) throws ParseException {
		init();//初始化
		show();//排序前显示
//		sortById();//按学号排序
//		sortByName();//按名字排序
		sortById();//按学生id排序
		System.out.println("排序后，再显示");
		show();//排序后，再显示
	}
}