#VARIABLES and TYPES#
Variables and types
A variable is a data name that is used to store the data value. Constant variable cannot be changed during the execution of a program.
A variable is a symbol or name that stands for a value. It is a value that can change. A variable can take different values during the execution. It can be choose by the programmer in many ways.
Example 1:
c = a + b
This is an example of programming expression.
a, b and c are variables.
Example 2:
- Average
- Total
- Count_1
- Class_strength
In every program, variable has its own:
·Name (Identifier)
·Data Type
·Size
·Value
Variable consists of letters, digits and the underscore (_) character. It has following conditions:
1 Uppercase and lower case is significant.
For example: The variable Average is not the same as average or AVERAGE
2 They must begin with a letter.
3 It should not be a keyword.
4 White space is not allowed.
Example of valid variable names is:
SUM1 ph_value Mumbai
John Value distance
Example of variable names
Variable Name | Valid? | Remarks |
First_tag | Valid | |
Price$ | Not valid | Dollar sign is not valid |
Average weight | Not valid | Blank space is not allowed |
Int_type | Valid | Keyword may be the part of a name |
Variables can represent numeric values, characters, character strings, or memory addresses.
Types of Variables in JAVA
Types of Variables
Local Variables Instance Variables Static Variables
·Local variable- A variable that is declared inside the method that is called local variable.
·Instance variable- A variable that declared the inside the class but outside the method that is called instance variable.
·Static variable-A static Variable is a special type of the variable that is shared by all objects from a class. Static variable are used to keep track of global information such as number of objects from a class
Example1:-
class Simple
{
public static void main(String[] args)
{
int a=10;
int b=10;
int c=a+b;
System.out.println(c);
}
}
Example2:-
class A
{
int data=50; //instance variable
static int m=100; //static variable
void method()
{
int n=90;//local variable
}
}//end of class