Current timestamp as filename in Java

Question

I want to name new files created by my Java application with the current timestamp.

I need help with this. How do I name the new files created with the current timestamp

Answer 1

Use SimpleDateFormat as aix suggested to format the current time into a string. You should use a format that does not include / characters etc. I would suggest something like yyyyMMddhhmm

Answer 2

Date, SimpleDateFormat and whatever classes are required on the I/O side of things (there are many possibilities).

Answer 3

No need to get too complicated, try this one liner:

String fileName = new SimpleDateFormat("yyyyMMddHHmm'.txt'").format(new Date());

Answer 4

try this one

String fileSuffix = new SimpleDateFormat("yyyyMMddHHmmss").format(new Date());

Answer 5

You can use DateTime

import org.joda.time.DateTime

Option 1 : with yyyyMMddHHmmss

DateTime.now().toString("yyyyMMddHHmmss")

Will give 20190205214430

Option 2 : yyyy-dd-M--HH-mm-ss

   DateTime.now().toString("yyyy-dd-M--HH-mm-ss")

will give 2019-05-2--21-43-32

Answer 6

Improving the @Derek Springer post with fill length function:

public static String getFileWithDate(String fileName, String fileSaperator, String dateFormat) {
    String FileNamePrefix = fileName.substring(0, fileName.lastIndexOf(fileSaperator));
    String FileNameSuffix = fileName.substring(fileName.lastIndexOf(fileSaperator)+1, fileName.length());
    //System.out.println("File= Prefix~Suffix:"+FileNamePrefix +"~"+FileNameSuffix);
    
    String newFileName = new SimpleDateFormat("'"+FileNamePrefix+"_'"+dateFormat+"'"+fileSaperator+FileNameSuffix+"'").format(new Date());
    System.out.println("New File:"+newFileName);
    return newFileName;
}

Using the funciton and its Output:

String fileSaperator = ".", format = "yyyyMMMdd_HHmm";
getFileWithDate("Text1.txt", fileSaperator, format);
getFileWithDate("Text1.doc", fileSaperator, format);
getFileWithDate("Text1.txt.json", fileSaperator, format);

Output:

Old File:Text1.txt   New File:Text1_2020Nov11_1807.txt
Old File:Text1.doc   New File:Text1_2020Nov11_1807.doc
Old File:Text1.txt.json  New File:Text1.txt_2020Nov11_1807.json