import java.time.*;
import java.time.format.*;
 
    class Validation{
 
         public void validateDateFormat(String format,String text){
 
DateTimeFormatter sdfrmt = DateTimeFormatter.ofPattern(format);
LocalTime testDate = null;
try {
    testDate = LocalTime.parse(text, sdfrmt);
} catch (DateTimeParseException e) {
    System.out.println("dateFormat Exception :" + e.getMessage());
    }
}
 
         public static void main(String []args){
            Validation val = new Validation();
            val.validateDateFormat("Hmm","747"); //working 
            val.validateDateFormat("Hmm","1637");//not working
         }
    }

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