This txtboxempty validating
, on the other hand, receives the character corresponding to a keyboard key.
This means that the value for the letter a is not the same as the letter A.
If you were to cancel further processing, that would effectively mean that it would be impossible to leave a text box until the data entered is valid.
The Because more than one text box is using this method to handle the event, you cannot be sure which is calling the function.
It is useful if you want to exclude a range of characters, for example, only allowing numeric values to be entered.
In the following Try It Out, you create a dialog on which you can enter your name, address, occupation, and age.
In this example, there are a number of criteria to enforce to ensure that the values are correct: .
The reason that this event needs a special handler is that should the validation fail, there must be a way to prevent any further processing.
the author claims there is not previous knowledge needed, but at this page he is throwing code at us and not telling us where it put it. jtwl_jtwl_, Now I don't have the book you're working with but I down loaded the code to have a look at it and it appears that the event should go in its own method like this. Jason "Is the glass half full, half empty, or twice as large as it needs to be?
An empty string is represented as are initialized with the value of the empty string by the Java Server Faces implementation.
Validating these strings can be an issue when user input for such fields is not required.
The Java programming language distinguishes between null and empty strings.
An empty string is a string instance of zero length, whereas a null string has no value at all.