日期类和格式化类

 1.输入两个日期，请问相差多少天

public class zy1 {
    public static void main(String[] args) {
//        Date d1=new Date(3213123);
//        Date d2=new Date(1231223);
//        long day=(d1.getTime()-d2.getTime())/1000/1000/24;
//        System.out.println(day);

        LocalDate ld1=LocalDate.of(2020,10,10);
        LocalDate ld2=LocalDate.of(2021,10,10);
        long between = ChronoUnit.DAYS.between(ld1, ld2);
        System.out.println(between);
    }
}

2.已知你的生日，请问你多大了？

public static void main(String[] args) {
        LocalDate ld1=LocalDate.of(1999,2,26);
        LocalDate ld2=LocalDate.now();

         long between = ChronoUnit.DAYS.between(ld1, ld2);
        long year=(between/365);
        System.out.println(year);
    }

3、新闻类：标题，内容，时间。有10条新闻，按照时间的降序排列。 

 

package week2.day3;

import java.time.LocalDate;

public class News {
    private String title;
    private String content;
    private LocalDate time;

    public String getTitle() {
        return title;
    }

    public void setTitle(String title) {
        this.title = title;
    }

    public String getContent() {
        return content;
    }

    public void setContent(String content) {
        this.content = content;
    }

    public LocalDate getTime() {
        return time;
    }

    public void setTime(LocalDate time) {
        this.time = time;
    }

    public News() {
    }

    public News(String title, String content, LocalDate time) {
        this.title = title;
        this.content = content;
        this.time = time;
    }

    @Override
    public String toString() {
        return "News{" +
                "title='" + title + '\'' +
                ", content='" + content + '\'' +
                ", time=" + time +
                '}';
    }
}

public class Date03 {

    public static void main(String[] args) {

        News   news1=new News("河大封校1","河大发现了一名密接者", LocalDate.of(2022,2,28));
        News   news2=new News("河大封校2","河大发现了一名密接者", LocalDate.of(2022,2,25));
        News   news3=new News("河大封校3","河大发现了一名密接者", LocalDate.of(2022,3,3));
        News   news4=new News("河大封校4","河大发现了一名密接者", LocalDate.of(2022,1,1));
        News   news5=new News("河大封校5","河大发现了一名密接者", LocalDate.of(2022,2,28));

        News[]   newsss={news1,news2,news3,news4,news5};

        
        for (int i = 0; i < newsss.length-1; i++) {
            for (int j = 0; j < newsss.length-1-i; j++) {
                News  n11=newsss[j];
                News  n22=newsss[j+1];

                if(n11.getTime().compareTo(n22.getTime())  < 0  ){
                    newsss[j]=n22;
                    newsss[j+1]=n11;
                }
            }    
        }

        for (int i = 0; i < newsss.length; i++) {
            System.out.println(newsss[i]);
        }


    }

4、学生类：姓名，学号，出生日期。
找出比“张三”大的所有同学信息。

package week2.day3;

import java.util.Calendar;

public class Student {
    private int num;
    private  String name;
    private Calendar brith;

    @Override
    public String toString() {
        return "Student{" +
                "num=" + num +
                ", name='" + name + '\'' +
                ", brith=" + brith +
                '}';
    }

    public Student() {
    }

    public Student(int num, String name, Calendar brith) {
        this.num = num;
        this.name = name;
        this.brith = brith;
    }

    public int getNum() {
        return num;
    }

    public void setNum(int num) {
        this.num = num;
    }

    public String getName() {
        return name;
    }

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

    public Calendar getBrith() {
        return brith;
    }

    public void setBrith(Calendar brith) {
        this.brith = brith;
    }

}

   public static void main(String[] args) {
        Student s1=new Student(21312,"张三",Calendar.getInstance());
        s1.getBrith().set(Calendar.MONTH,2);
        Student s2=new Student(2131,"张三1",Calendar.getInstance());
        s2.getBrith().set(Calendar.MONTH,3);
        Student s3=new Student(2132,"张三2",Calendar.getInstance());
        s3.getBrith().set(Calendar.MONTH,1);
        Student s4=new Student(1312,"张三3",Calendar.getInstance());
        s4.getBrith().set(Calendar.MONTH,6);


        Student[] students={s1,s2,s3,s4};
        Calendar zhangsan=null;
        for (int i = 0; i < students.length; i++) {
            if (students[i].getName().equals("张三")){
                zhangsan=students[i].getBrith();
                break;
            }

        }
        for (int i = 0; i < students.length; i++) {
            if(students[i].getBrith().compareTo(zhangsan)<0){
                System.out.println(students[i]);
            }

        }
    }

5、请问今天是今年的第多少天？

public class Date05 {

    public static void main(String[] args) {


        LocalDate   d1=LocalDate.now();
        int dayOfYear = d1.getDayOfYear();
        System.out.println(dayOfYear);

        Calendar  c=Calendar.getInstance();
        c.get(Calendar.DAY_OF_YEAR);


    }
}