Depending on the Content Holds by variable they are divided into TWO categories 1. Primitives Variable: A primitive can be one of eight types: char, boolean, byte,short, int, long, double, or float. Once a primitive has been declared, its primitive type can never change, although in most cases its value can change. 2. Reference variables A reference variable is used to refer to (or access) an object. A reference variable is declared to be of a specific type and that type can never be changed. Reference variable can be used to hold object references. Ex: String string1=”Sekhar4J”; Here string1 is a String object Primitive variable ca n be used to hold primitive values. Example: int i=10; int[][] a={{1,2},{3,4,5},{6,7,8,9},{}}; for(int i=0;i <= a ;i++) System.out.println(a[i].length); } output: 2,3 ,4,0 Depends on the position at which it is declared all the variables divided into 3 categories...