In ConstraintValidator<Password, String>, the two generic type parameters are:
First parameter: Password
- This is the annotation type that this validator handles
- It's a custom validation annotation (like @Password) that you would create
- When someone uses @Password on a field, this validator will be called
- Example: @Password private String userPassword;
Second parameter: String
- This is the data type of the value being validated
- It tells the validator what type of object it will receive in the isValid() method
- In this case, it expects a String value (the password)
- The isValid(String password, ...) method parameter matches this type
How it works:
- You create a @Password annotation
- Apply it to a String field: @Password String myPassword
- When validation runs, this validator receives the String value
- The isValid() method validates that String and returns true/false
Other examples:
- ConstraintValidator<Email, String> - validates email strings
- ConstraintValidator<Min, Integer> - validates minimum integer values
- ConstraintValidator<NotNull, Object> - validates any object is not null
The generic types ensure type safety between the annotation and the value being validated.