For example, if a thrown exception object has class IllegalArgumentException, that indicates someone passed an illegal argument to a method. Sometimes you will want to indicate that a method encountered an abnormal condition that isn't represented by a class in the Throwable family of java.lang.
Actually, zero is neither a negative or a positive number. The whole idea of positive and negative is defined in terms of zero. Negative numbers are numbers that are smaller than zero, and positive numbers are numbers that are bigger than zero. Since zero isn't bigger or smaller than itself (just like you're not older than yourself, or taller than yourself), zero is neither positive nor negative.
We think of the numbers as either positive or negative. But actually, all real numbers can be divided into three categories: positive, negative and zero. This is one of the reasons zero can be forgotten in all this mix. With so many other numbers to be positive and negative, zeroâs truly in a class by himself.