Customised Exception handling class.....

Question

Hello Friends,
I am working on a project for which I need to create my own exception handling class.
The reason I need this class is to catch any exceptions and get a customised error message
according to each exception and then be able to display those messages on web page.
some examples of the exception I want to catch and display appropriate message are..
1. a duplicate reord in db
2. wrong data type (this will deal with ints,doubles and strings data types)
3. date type validation ( to make sure its date object instead of a string)
and there are several more messages but if can get some help or idea from any one to design a class for the above errors I might be able to manage other errors as well.
greatly appreciate any respnses.

Answer 1

First off, you can extend Exception:
public class MyException extends Exception {
}You can put some custom messages into the class:
public class MyException extends Exception {
  public static final String DUPLICATE_RECORD = "Duplicate record in db",
                       WRONG_DATA_TYPE = "Wrong data type",
                       VALIDATION_ERROR = "Invalid data type";
}Then, have your constructors, which take a String as an argument, so they can get your 'presets' or a custom message:
public class MyException extends Exception {
  public static final String DUPLICATE_RECORD = "Duplicate record in db",
                       WRONG_DATA_TYPE = "Wrong data type",
                       VALIDATION_ERROR = "Invalid data type";
  public MyException(String message) {
    super(message);
}You could also have a series of exception classes: DuplicateRecordException, WrongDataTypeException, ValidationException, etc. Hope that helps.
m