validate a date format in (mm/yyyy) type in java

Question

how to validate date format MM/YYYY as String example-

09/20 false

13/5651 false

3/2104 true

03/2010 true

Answer 1

Use YearMonth class.

DateTimeFormatter f = DateTimeFormatter.ofPattern( "M/uuuu" ) ;
YearMonth ym = YearMonth.parse( "3/2018" , f ) ;

Trap for DateTimeParseException to detect invalid input.

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Tip: Use standard ISO 8601 formats for exchanging date-time values as text. For year-month: YYYY-MM

The java.time classes use these standard formats by default.

YearMonth.parse( "2018-03" ) 

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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.

Answer 2

What you want is a customized method because you place special constraints to the validity of the date.
The following passed all your 4 examples:

public static boolean validDate(String date) {
    date = date.trim();
    if (date.length() < 6)
        return false;

    String[] parts = date.split("/");
    if (parts.length != 2)
        return false;

    int month = 0;
    try {
        month = Integer.parseInt(parts[0]);
    } catch (NumberFormatException e) {
        e.printStackTrace();
        return false;
    }
    if (month < 1 || month > 12)
        return false;

    int year = 0;
    try {
        year = Integer.parseInt(parts[1]);
    } catch (NumberFormatException e) {
        e.printStackTrace();
        return false;
    }
    if (year < 1000)
        return false;

    return true;
}

public static void main(String[] args) {
    String s1 = "09/20";
    String s2 = "13/5651";
    String s3 = "3/2104";
    String s4 = "03/2010";

    System.out.println(s1 + " " + validDate(s1));
    System.out.println(s2 + " " + validDate(s2));
    System.out.println(s3 + " " + validDate(s3));
    System.out.println(s4 + " " + validDate(s4));
}

will print:

09/20 false
13/5651 false
3/2104 true
03/2010 true

I'm not sure about this part:

if (year < 1000)
    return false;

you can change it if you like.

Answer 3

public boolean isThisDateValid(String dateToValidate, String dateFromat){

    if(dateToValidate == null){
        return false;
    }

    SimpleDateFormat sdf = new SimpleDateFormat(dateFromat);
    sdf.setLenient(false);

    try {

        //if not valid, it will throw ParseException
        Date date = sdf.parse(dateToValidate);
        System.out.println(date);

    } catch (ParseException e) {

        e.printStackTrace();
        return false;
    }

    return true;
}

Referensi https://www.mkyong.com/java/how-to-check-if-date-is-valid-in-java/