Variables

Variables

üVariable is a name for a location in memory.

üDeclaring a variable:

  type identifier [=value][,identifier [=value]….];

üThe initialization expression must result in a value of the same 

or compatible type as that specified for the variable.

üWhen a variable is not initialized, the value of that variable is 

undefined.

Scope and Lifetime of a variable

üA block begins with an opening curly brace and ends by a 

closing curly brace.

üA block determines scope, that defines which objects 

are visible to other parts of your program.

üVariables declared within a block localize themselves.

üIn case of nested block, the outer block encloses the

 inner block. The variables declared in the outer block 

is visible to the inner block but the reverse is not true.

üA variable will not hold it’s value once it has gone out 

of it’s scope.

üIn an inner block, it is not possible to declare a 

variable of the same name as in outer block.

Scope and Lifetime of a variable

Example:

public static void main( String args[])

{

  int x =10;

  if ( x == 10)

  {

  int y =20;

  System.out.println(“x and y: “ +x +” “+y);

  x= y * 2;

  }

  y= 100;  //Error

  System.out.println (“x is “+x);

}