Java variable
A variable is a name which is used to hold the constant value while the java program is executed .
int a=100;
here, variable a is associated with the value 100, and int represents the data type of variable.
How to declare variables ?
Variable declaration in java composed of 4 component
1) Variable type
2) Variable name
3) Zero or more modifier
4) Constant value /Literal
syntax : variable declaration
public int empId =10 ;
Here ,
public : Modifier name
int : Data type
empId : variable name
10 : Constant value
Types of variable in Java
Variable in java divided into 3 sub parts
1) Local Variable
2) Instance Variable
3) Static Variable
Local Variable
The variable which are defined within a method / blocks / Constructor are know as the local variable .
- Local variable memory allocated when the method starts and destroyed when method completed.
- In java local variable are stored in stack memory .
Example (1): Local Variable
class Test
{
public static void main(String[] args)
{
int a=100; //Local variable
int b=100; //Local variable
int c=a+b; // Local variable
System.out.println(c);
}
}
0utput : 200
Example (2): Local Variable (when try to access out side of the method / block /constructor ).
{
public static void main(String[] args)
{
int a=100; //Local variable
int b=100; //Local variable
System.out.println(a); //Possible
}
Void add()
{
System.out.println(a+b); // Not Possible
}
}
Output : Compilation error
Instance Variable ( Non-static variable )
Instance Variable ( Non-static variable )
The variable which are defined within class but outside of a method are know as the instance variable .
Example : Instance variable
class Test
{
Static Variable (class variable )
The variable which are defined within class but outside of a method with the static modifiers are know as the static variable .
- Instance variable memory allocated during the time of object creation and destroyed when the object is destroyed.
- In java instance variable are stored in heap memory .
Example : Instance variable
class Test
{
int a=100; //Instance variable
int b=200; // Instance variable
public static void main(String[] args)
{
Test t = new Test();
System.out.println(t.a);
System.out.println(t.b);
t.add()
System.out.println(t.b);
t.add()
}
Void add()
{
System.out.println(a);
System.out.println(b);
System.out.println(b);
}
}
Outpout :
100
200
100
200
Outpout :
100
200
100
200
Static Variable (class variable )
The variable which are defined within class but outside of a method with the static modifiers are know as the static variable .
- Static variable memory allocated during the time of .class file loading and destroyed when the execution ends.
- In java static variable are stored in method area .
- Static variable can not be local.
Example : static variable
class Test
{
static int a=100; //Static variable
static int b=200; //Static variable
Hope !!! The above lesson of variable in java helpful for you ...
class Test
{
static int a=100; //Static variable
static int b=200; //Static variable
public static void main(String[] args)
{
System.out.println(Test.a);
System.out.println(Test.a);
System.out.println(Test.b);
Test t = new Test();
t.add()
Test t = new Test();
t.add()
}
Void add()
{
System.out.println(Test.a);
System.out.println(Test.b);
System.out.println(Test.b);
}
}
Outpout :
100
200
100
200
Hope !!! The above lesson of variable in java helpful for you ...
Technology Team,
UPCS
UP Consultancy Services
Tags : Java variables , variables in java , local variables in java , class variable in java , Scope of variables in java , Instance variable in java
Variable In Java Types of Variable in Java |