data type validation

[cagipple]

Is there a way to restrict the user to enter a specific type of data?

[pbrockway2]

Not without special hardware which is not common on most PCs, and illegal in many jurisdictions.

A better approach is to not accept the bad data they do enter. For example you might ask for a telephone number and when they have entered it check to see if it conforms to your expectations.

Many would argue better (and possibly what you were getting at) is to use a GUI component like JFormattedTextField which restricts the value of user entered strings. (It is described in Oracle's Tutorial at the page How to Use Formatted Text Fields). Another approach - which could be used with any text component - is to set a document filter. (Its use is also described in the Tutorial: here.)

[Eranga]

So basically there is no specific way to do this. Depends on the controls you are using and the design, we can take different approaches. However, if we consider web applications we are more towards to do the validations on client-side and try to avoid overheads on servers. When comes to the desktop application anyway life is more easy.