Variables and data types

3.1 Variables A variable provides us with named storage that our programs can manipulate. Each variable in Java has a specific type, which determines the size and layout of the variable's memory; the range of values that can be stored within that memory; and the set of operations that can be applied to the variable. You must declare all variables before they can be used. The basic form of a variable declaration is shown here: data_type variable = value; Here data type is one of Java's datatypes and variable is the name of the variable. To declare more than one variable of the specified type, you can use a comma-separated list. Following are valid examples of variable declaration and initialization in Java: int a, b, c; // Declares three ints, a, b, and c. int a = 10, b = 10; // Example of initialization double pi = 3.14159; // declares and assigns a value of PI. char a = 'a'; // the char variable a iis initialized with value 'a' Constant: During the execution of program, value of variable may change. A constant represents permanent data that never changes. If you want use some value likes p=3.14159; no need to type every time instead you can simply define constant for p, following is the syntax for declaring constant. Static final datatype ConstantName = value; Example: static final float PI=3.14159;