Declaration of a Variable

Here is a program that uses the variable payAmount.

class Example
{
  public static void main ( String[] args )
  {
    long payAmount = 123;    //a declaration of a variable

    System.out.println("The variable contains: " + payAmount );
  }
}

The line   long payAmount = 123;   is a declaration of a variable. A declaration of a variable is where a program says that it needs a variable. For our small programs, declaration statements will be placed between the two braces of the  main   method.

The declaration gives a name and a data type for the variable. It may also ask that a particular value be placed in the variable. In a high level language (such as Java) the programmer does not need to worry about how the computer hardware actually does what was asked. If you ask for a variable of type long, you get it. Details like bytes and memory addresses are up to the Java compiler.

In the example program, the declaration requests a 64 bit section of memory named payAmount which uses the primitive data type long. When the program starts running, the variable will initially have the value 123 stored in it.

A variable cannot be used in a program unless it has been declared. A variable can be declared only once.