How do I check if a string is in this format MM-YY in Java ?

Question

I have to add into a Database a string in format "MM-YY" which represents expiration date from a Credit Card , where MM is the month and YY are the last two digits of the Year , how do I check if a String is in this this specific format in Java ?

Answer 1

Use a regular expression:

String myString = "12-99";

if( myString.matches("((0[1-9])|(1[0-2]))-\\d{2}") ){
   System.out.println("Correct format");
}
else{
  System.out.println("Incorrect format");
}

Answer 2

Try Using below regex

String str = "10-18";
if (str.matches("([0-9]{2})-([0-9]{2})"))
 System.out.println("Correct");
else 
System.out.println("Incorrect");

Answer 3

java.time.YearMonth

Parse as a YearMonth. Trap for exception.

String input = "99-18" ;  // Valid: "01-18"  Invalid: "99-18"
DateTimeFormatter f = DateTimeFormatter.ofPattern( "MM-uu" ) ;

YearMonth ym = null ;
try {
    ym = YearMonth.parse( input , f ) ;
} catch ( DateTimeParseException e ) {
    System.out.println( "Invalid input: " + input ) ;
}

System.out.println( "ym.toString(): " + ym ) ;

See this code run live on IdeOne.com.

Invalid input: 99-18

ym.toString(): null

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About java.time

The java.time framework is built into Java 8 and later. These classes supplant the troublesome old legacy date-time classes such as java.util.Date, Calendar, & SimpleDateFormat.

The Joda-Time project, now in maintenance mode, advises migration to the java.time classes.

To learn more, see the Oracle Tutorial. And search Stack Overflow for many examples and explanations. Specification is JSR 310.

You may exchange java.time objects directly with your database. Use a JDBC driver compliant with JDBC 4.2 or later. No need for strings, no need for java.sql.* classes.

Where to obtain the java.time classes?

• Java SE 8, Java SE 9, Java SE 10, Java SE 11, and later - Part of the standard Java API with a bundled implementation.
  • Java 9 adds some minor features and fixes.
• Java SE 6 and Java SE 7
  • Most of the java.time functionality is back-ported to Java 6 & 7 in ThreeTen-Backport.
• Android
  • Later versions of Android bundle implementations of the java.time classes.
  • For earlier Android (<26), the ThreeTenABP project adapts ThreeTen-Backport (mentioned above). See How to use ThreeTenABP….

The ThreeTen-Extra project extends java.time with additional classes. This project is a proving ground for possible future additions to java.time. You may find some useful classes here such as Interval, YearWeek, YearQuarter, and more.