2

I have java date string.

How can I change its year without changing the month and date.

e.g.

parts1[1]=   2020-1-2;
parts1[2]=   13:48:21;
CreatedDate = parts1[1]+" "+parts1[2];   
System.out.println(CreatedDate);

I want to change it to

parts1[1]=   2021-1-2;
parts1[2]=   13:48:21;
CreatedDate = parts1[1]+" "+parts1[2];   
System.out.println(CreatedDate);

I basically want to change the year without changing month and date

Can it be done?

Arvind Kumar Avinash
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Kumar
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  • This code is not valid Java and incomplete. Please edit your question to include what the (exact) desired input and output is. Currently it is unclear if you want part of the string array or part of the full string changed. – Matt Jan 02 '21 at 08:43
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    It would be easier if you parsed the `String` into a `LocalDate`, then performed the necessary operations on it. If you have to, afterwards you can convert the `LocalDate` back into a `String`. – Slaw Jan 02 '21 at 08:49
  • Tip: Your work will be easier if you use [ISO 8601](https://en.m.wikipedia.org/wiki/ISO_8601) formats for text representing date-time values. You are close to compliance but need to always include the padding zero on single-digit month and day numbers. So, `2020-01-02`. Use only ISO 8601 when serializing to text files or exchanging data between systems. Use other formats only for user-interface. – Basil Bourque Jan 02 '21 at 20:10

2 Answers2

4

java.time

You do not have to split the string and then combine the parts. You can parse the whole string into LocalDateTime and then use LocalDateTime#withYear to get a new instance with the specified year.

import java.time.LocalDateTime;
import java.time.format.DateTimeFormatter;
import java.util.Locale;

public class Main {
    public static void main(String[] args) {
        String creationDateTime = "2020-1-2 13:48:21";
        DateTimeFormatter dtf = DateTimeFormatter.ofPattern("uuuu-M-d H:m:s", Locale.ENGLISH);
        LocalDateTime ldt = LocalDateTime.parse(creationDateTime, dtf);
        System.out.println(ldt);
        ldt = ldt.withYear(2021);

        // Default format
        String updatedDateTime = ldt.toString();
        System.out.println(updatedDateTime);

        // Custom format
        updatedDateTime = ldt.format(dtf);
        System.out.println(updatedDateTime);
    }
}

Output:

2020-01-02T13:48:21
2021-01-02T13:48:21
2021-1-2 13:48:21

Learn more about java.time API from Trail: Date Time.

Arvind Kumar Avinash
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0

try:

String[] arrOfStr = parts1[1].split("-", 2);

arrOfStr[0] contains the year

Now you need to parse it as an int (since it's only 4 digits)

int year = Integer.parseInt(arrOfStr[0]);

year now contains the the number 2020.

you can do

year++;

to increase it's value by 1

and to put it back in String format do:

arrOfStr[0] = "" + year;

or

arrOfStr[0] = String.valueOf(year);

to put it all together do this

parts1[1]= arrOfStr[0] + "-" arrOfStr[1]; //  2021-1-2

finally it should look like this:

parts1[1]=   2020-1-2;
parts1[2]=   13:48:21;

String[] arrOfStr = parts1[1].split("-", 2); 
int year = Integer.parseInt(arrOfStr[0]);  
year++;
arrOfStr[0] = "" + year;
parts1[1]= arrOfStr[0] + "-" + arrOfStr[1];


CreatedDate = parts1[1]+" "+parts1[2];   
System.out.println(CreatedDate);
S. Kafetzopoulos
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