How to check whether a Birth Date entered is valid

Question

A user enters his birth date in a jTextfield in the yyyy/mm/dd and I want to make sure that he enters it correctly like that and also that it is a real date. this is my code so far:

SimpleDateFormat df = new SimpleDateFormat("yyyy/mm/dd");  
Date testDate = null;

Birth = jTextField3.getText();

try{  
    testDate = df.parse(Birth);
} catch (ParseException e){ }      
if (!df.format(testDate).equals(Birth)){  
    JOptionPane.showMessageDialog(rootPane, "invalid date!!");
}

the error I am getting is it said I cant cast a java.sql.Date into a java.util.Date

Answer 1

mm is minutes. MM is months:

SimpleDateFormat df = new SimpleDateFormat("yyyy/MM/dd");

See the documentation for more details.

You should set that to be strict ( df.setLenient(false) , and then you don't need to try to format the result again - just the parse exception should be enough.

Personally I'd use Joda Time for any date/time work in Java though - it's a much nicer API.

As for java.util.Date vs java.sql.Date - the code you've given us would entirely use java.util.Date . If you've already got an import for java.sql.Date which you want to preserve, you'd want something like:

java.util.Date testDate = ...;

Although as you don't need to reformat it, you may not even need a variable at all:

SimpleDateFormat df = new SimpleDateFormat("yyyy/MM/dd");
df.setLenient(false);
Date testDate = null;
boolean valid = false;
try {
    df.parse(jTextField3.getText());
    valid = true;
}
catch (ParseException e) { } // valid will still be false
if (!valid) {  
    JOptionPane.showMessageDialog(rootPane, "invalid date!!");
}

(Or you could show the message dialog in the catch block, but then you can't easily have an else clause for the success case...)