A method is a contract; when we define one, we put our thoughts into it. We specify the parameters with their type and also a return type. When we invoke a method, we expect it to behave according to the contract. If it doesn’t, it’s a violation of the contract.

We deal with such a violation all the time. We invoke a method with its proper arguments, and we get a return. However, sometimes we end up getting a null, which is, in fact, a clear violation. We shouldn’t accept such a violation. If a method cannot return the value of the specified type, it should mention that in the method signature, the method may or may not be returning the value you are expecting. If we know it from the method signature, we then write our code accordingly.

Source: DZone