CODEWITHSUNDEEP
javaexceptionsimpledateformat
indieNik
indieNik

Reputation: 134

Java Parse Exception to Custom Exception

I'm new to Java and my problem here is a Simple Age Calculator. Here is my Code:

public class Client {
public int findAge(String birthDate) throws InvalidDateFormatException {
//  InvalidDateFormatException is a custom defined

    int age = 0;
    try {
        Calendar past = new GregorianCalendar();
        Calendar present = Calendar.getInstance();
        past.setTime(new SimpleDateFormat("dd-MM-yyyy", Locale.ENGLISH).parse(birthDate));
        age = present.get(Calendar.YEAR) - past.get(Calendar.YEAR); 
    } catch (ParseException e) {
        // TODO Auto-generated catch block
        e.printStackTrace();
}
    return (age >= 0) ? age : 0;
}

In main,

try {
                System.out.println(c.findAge("08-09-1015"));
            } catch (InvalidDateFormatException e) {
                // TODO Auto-generated catch block
                e.printStackTrace();
            }

Now, this is throwing a ParseException every time i pass a String in the wrong Format. Is there any way in which I can make it throw an InvalidDateFormatException Exception instead?

Also, please leave a comment on the style and quality of my Code, provided I'm following the correct coding standards and adhering to best practices.

Upvotes: 1

Views: 3679

Answers (2)

Tunaki
Tunaki

Reputation: 137084

To answer your prime question, you need to throw the custom exception in the catch block:

try {
    Calendar past = new GregorianCalendar();
    Calendar present = Calendar.getInstance();
    past.setTime(new SimpleDateFormat("dd-MM-yyyy", Locale.ENGLISH).parse(birthDate));
    age = present.get(Calendar.YEAR) - past.get(Calendar.YEAR); 
} catch (ParseException e) {
    throw new InvalidDateFormatException("invalid date: " + birthDate);
}

Regarding your code, I have a couple of suggestions:

  • Do not use new GregorianCalendar() and prefer Calendar.getInstance().
  • The way you calculate the age is broken: you don't take into account the month and the day (let's say we are 2015-09-20, and the birth date is 2014-12-01, your code will output 1 even if the baby is not 1 year old yet).
  • Consider giving a Date argument instead of a String argument. It should not be the responsibility of the findAge method to parse the birth date.
  • If you are using Java 8, consider using the new Java Time API.

Upvotes: 3

Vasu
Vasu

Reputation: 22422

Define Custom Exception class for InvalidDateFormatException as below:

public class InvalidDateFormatException extends RuntimeException {

    private String errorMessage;

    public InvalidDateFormatException(String errorMessage, Exception exe) {
        super(errorMessage);
        exe.printStackTrace();
    }
}

Modify your catch block to throw the exception as below : 

public class Client {
public int findAge(String birthDate) throws InvalidDateFormatException {
    int age = 0;
    try {
        Calendar past = new GregorianCalendar();
        Calendar present = Calendar.getInstance();
        past.setTime(new SimpleDateFormat("dd-MM-yyyy", Locale.ENGLISH).parse(birthDate));
        age = present.get(Calendar.YEAR) - past.get(Calendar.YEAR);
    } catch (ParseException e) {
        throw new InvalidDateFormatException("Invalid Date Format while finding Age", e);
    }
    return (age >= 0) ? age : 0;
 }
}

Also, I would suggest you go through the below site: https://docs.oracle.com/javase/tutorial/essential/exceptions/creating.html

Upvotes: 1

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