It doesn't take much Java development experience to learn firsthand what the NullPointerException is about. In fact, one person has highlighted dealing with this as the number one mistake Java ...

NullPointerException in Java - Explaining the billion dollar mistake What is null pointer exception in Java? By Adam Sinicki • ...

Some exceptions in Java must be handled in the developer's code. Other exceptions can occur without any exception handling semantics at all. When an exception must be handled with try-and-catch ...