Why is throwing an exception better than returning an error value?
Conclusion. When you code using return codes, you’re preparing yourself for failure, and hope your fortress of tests is secure enough. When you code using exception, you know that your code can fail, and usually put counterfire catch at chosen strategic position in your code.
How do you handle exceptions in DAO?
its a good idea to create your own independant exceptions for each layer. For example, if you are using a particular DAO implementation, you should wrap the implementation specific exception to your own generic exception and throw it forward to Service Layer.
When to throw exception or return false in Dao?
It has no way of knowing if the input came from another system, a file, or a user. It has no way of knowing how, or even if, the error could be sorted out through interact with the user. In this case the standard way for the DAO object to signal the error is to throw an exception.
When to throw an exception or return false?
Rather they return true or false. There is no need to throw an exception even if the input data is invalid. In contrast, inside a DAO class you will most likely not be able to interact with the user to correct the error. A DAO object may not even know if it is called from inside a web service, a servlet, or somewhere else.
Which is an example of the Dao pattern?
The example is contrived, but it shows, in a nutshell, the motivations behind the DAO pattern. In this case, the main method just uses a UserDao instance to perform CRUD operations on a few User objects.
Do you have to throw exceptions in validation?
Notice how none of the validation methods throw exceptions. Rather they return true or false. There is no need to throw an exception even if the input data is invalid. In contrast, inside a DAO class you will most likely not be able to interact with the user to correct the error.