Java: convert birth data to days

问题:

I really need some help with the specific assignment. The user inputs birth data (YYYY MM DD) and the program tells you how old you are in days :

The outprint in console would be

You are for example born 1981 11 06

You are 7068 days old.

I've rewritten my code maybe 20 times without success, and any help would be so much appreciated, i'm kinda new so everything will be helpful! thanks a lot in advance, Sebastian.

// the code ... :) EDITED .. I RE-WROTED THE CODE, since it didnt work anyhow i twisted and turned it so i changed it completly, but can someone tell me why DateFormat and Date date is not working Eclipse is also giving me error on ParseException..

Its working perfectly now ! thanks for all support!

回答1:

Have you considered the Calendar class? It has functions for parsing dates from strings and comparing them.

回答2:

Use the DateFormat class which you can utilize the .parse() on the input. Which gives you a Date class which then has .getTime() which returns the number of milliseconds. Then create a new Date class and subtract the .getTime() milliseconds. Convert to Days.

Date birth = DateFormat.parse(inputString);
Date now = new Date();
long diff = now.getTime() - now.getTime();
int days = ((((diff / 1000) / 60) / 60) / 24)

EDIT: According to the code you listed below, you should just be able to do

Scanner input=new Scanner(System.in);
System.out.print ("Enter birth date (yyyy/mm/dd): ");
String yourBirthDay=input.nextLine();
Date birth = DateFormat.parse(yourBirthDay);
Date now = new Date();
long diff = now.getTime() - now.getTime();
int days = ((((diff / 1000) / 60) / 60) / 24)

回答3:

Well, when I imported the needed class, it worked just fine:

import java.text.DateFormat;
import java.text.ParseException;
import java.text.SimpleDateFormat;
import java.util.Calendar;
import java.util.Date;

The error Eclipse gave you is probably because you didn't import the correct classes.

A little hint: use ctrl + shift + o to add missing imports in eclipse

回答4:

java.time

In Java 8 and later, you could use the java.time classes such as ChronoUnit and LocalDate. Perhaps not appropriate to a homework assignment though.

long days = ChronoUnit.DAYS.between( LocalDate.parse( "1981-11-06" ) , LocalDate.now( ZoneId.of( "America/Montreal" ) ) ) ;