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 ...

Ever come across the null pointer exception in Java? We explain what this error message means, why it happens, and how to avoid the billion-dollar mistake.

Java provides the throw statement for this purpose. For example, throw new IOException("unable to read file"); creates a new java.io.IOException object that’s initialized to the specified text.