Here is a little java snippet that can be used to validate if a date is in a certain format such as MM/DD/YYYY. This is useful when you need your user to input a date from the console. Of course if you are writing serious software you are going to have that user use a date picker in the GUI, but even then it might be useful to double check to make sure your end user isn’t slipping in any values they shouldn’t be.

If you want to see how this works or change it for yourself it might be helpful to check out the documentation on the SimpleDateFormat object: http://docs.oracle.com/javase/1.4.2/docs/api/java/text/SimpleDateFormat.html

Be sure to import:

import java.text.ParseException;
import java.text.SimpleDateFormat;
import java.util.Date;

This function will output a boolean which evaluates true if the date is valid.

public static boolean valiDate(String date) {
	SimpleDateFormat formatchk = new SimpleDateFormat("MM/dd/yyyy");
	Date Me = null;
	try {
		Me = formatchk.parse(date);
	} catch (ParseException e) {
		System.out.println("Invalid Date");
		return false;
	}
	if (!formatchk.format(Me).equals(date))
	{
		System.out.println("Invalid Date");
		return false;
	}
	return true;
}

Example:

// Assuming scanner is imported
Scanner keyboard = new Scanner(System.in);
System.out.println("Enter the person's birthday:");
String birthday = keyboard.next();
if(valiDate(birthday)) {
	//DO STUFF SON
} else {
	//YA DONE FAILED AT INPUTTIN'
}