Question

Sometimes I see programmers that use “assert”, and other times I see null checking for parameters and throws Exception.

What’s the best option?

Answer 1

Take always into account that an “assert” is not always enabled. This is the main rule you should have always in your mind. Think of it as a mechanism to detect bugs in your code, unexpected situations that should not happen (pre/postconditions). On the other hand, throw an exception (i.e. IllegalArgumentException) if there is a chance to get that null value from the caller.

For example:

• If you are creating a library to third parties, you can not verify the arguments with assert.
• In a private method, you can use assert to include pre/postconditions that must be met.