The document discusses static vs instance methods and variables in Java. Static methods and variables have a single copy associated with the class, while instance methods and variables are associated with each object. Static blocks allow initialization of static variables and run when the class is loaded. Static classes cannot be inherited and can only contain a static constructor. Methods are functions in object-oriented programming that perform operations on objects or classes.

1. Method, Static
1
www.infoviaan.com

2. static vs instance
• Static – Assign memory once in life.
• Static variable or static method can call inside static or
non-static area.
• Use static keyword to declare static, method or variable
• Using static, can call directly with class name
ex. ClassName.StaticMethodOrVariable;
• Non- static (Instance) – non-static variable or method are
called instance variable or instance method.
• No one keyword, for declare instance.
• Instance is accessed only, non-static area.
Class
Instance
static
Attributes
Instance
static
Methods
2
www.infoviaan.com

3. static with variable
public class StaticVariable{
static int x = 789; //static variable
String name = “Laddu”; //non-static (instance) variable
public static void main(String args[]) {
StaticVariable sv = new StaticVariable();
System.out.println(sv.x);
System.out.println(StaticVariable.x);
System.out.println(sv.name);
System.out.println(StaticVariable.name);
//Compile Time Error
}
}
3
www.infoviaan.com

4. static block
• Static block is used for initializing the static variables.
• This block gets executed when the class is loaded in the
memory.
• A class can have multiple Static blocks, which will
execute in the same sequence in which they have been
written into the program.
4
www.infoviaan.com

5. Program - static block
public class TestStaticBlock {
static int x = 10;
public static void main(String[] args) {
System.out.println(x+10 +" From Main Method");
}
static {
System.out.print(x + " From Static block n");
}
}
10 From Static block
20 From Main Method
// Executes before main method
// Executes After static block
5
www.infoviaan.com

6. static class
• Static classes are sealed and therefore cannot be
inherited.
• They cannot inherit from any class except Object.
• Static classes cannot contain an instance constructor.
however, they can contain a static constructor.
• It is Nested class
6
www.infoviaan.com

7. Use of static
static
class
method
variable Only one time memory allocation
Can be call with Object,
Without Object, and with class name also
Nested class
7
www.infoviaan.com

8. Function in OOP - Method
• Method – Perform specific operation.
• Categorised into 4 types
1.No Return value and No Arguments
2.No Return value with Arguments
3.Return Value but No Arguments
4.Return Value with Arguments
• Object - Memory instantiation.
8
www.infoviaan.com

9. No Return value and No Arguments
void display( )
{
System.out.println(“Hello! This is Display method”);
}
static void sum()
{
int a,b,c; // Local variable
a = 45;
b = 35;
c = a + b;
System.out.println(“Sum Result is : ”+ c);
}
public static void main(String args[]){
sum(); //No CE, static method
display(); //Compilation error, method is not static
} 9
www.infoviaan.com

10. No Return value with Arguments
public class MethodArgument{
static void info(int age, String name ) {
System.out.println(“Hello! My name is: ”+ name + “n My
age is: ”+ age);
}
void div(double x, int y){
double z = x/y;
System.out.println(“Division Result is: ”+ z);
}
public static void main(String args[]) {
info(25, “Ramdev”);
MethodArgument obj; //object declaration
obj = new MethodArgument(); //object instantiation
obj.div(1123.50, 50); //method calling, used with
object
}
} 10
www.infoviaan.com

11. Return Value but No Arguments
public class MethodReturn{
String info() {
String fullInfo = “Hello! My name is: Ramdev n My age
is: 60 ”
return fullInfo;
}
int multilply(){
int x=78, y=10;
return x*y;
}
public static void main(String args[]) {
MethodReturn m = new MethodArgument();
String s = m.info();
System.out.println(s);
System.out.println(“Result of Multiplication: ” +m.multiply());
}
} 11
www.infoviaan.com

12. Return Value with Arguments
public class A {
double area(double radius){
return 3.1415*radius*radius;
}
String details(String name, String address, int age, double salary){
String complete = “Name is : ”+name + “n Age is :”+age + “n
Salary is : ”+ salary+ “n Address is: ”+address;
return complete;
}
public static void main(String args[]) {
A a = new A();
A ob = new A();
System.out.println (“Area of Circle is : ” +a.area(2.5));
System.out.println (“Area of Circle is : ” +b.area(3.2));
System.out.println(a.details(“Mark jukerburg”, “USA”,
32, 36872782.8907));
}
} 12
www.infoviaan.com

13. Calculator
public class Calculator {
int a, b, c; //instance/class variable
public void sum(){
a = 89; b = 78;
c = a + b ;
System.out.println(“Sum Result is: ”+ c);
}
public void subtract(int x, int y){
a= x-y;
System.out.println(“Subtraction Result is: ”+ a);
}
public double division(){
double a,b;
a = 123.678;
b = 5.8;
return a/b;
} 13
www.infoviaan.com

14. Calculator cont.
public double multiply(double d1, double d2){
return d1*d2;
}
public static void main(String args[]) throws IOException {
Calculator obj = new Calculator();
int choice;
do{
System.out.println(“Enter a for Additionn Enter s for
Subtraction n Enter m for Multiplication n Enter d
for Division n Enter e for Exit ”);
choice = System.in.read();
switch(choice){
case ‘a’ : obj.sum(); break;
case ‘s’ : obj.subtract(356, 89 ); break;
case ‘d’ : System.out.println(“Division Result: ”+obj.div(); break;
case ‘m’: System.out.println(“Multiplication Result:
” + obj.multiply(123.34, 78.90); break;
case ‘e’: break; }
}while(choice!=‘e’);
}
} 14
www.infoviaan.com

15. QA
1. Difference between static & instance?
2.How to execute statement before main
method?
3.Why function are called method in OOP?
4.What is static block & class explain?
5.What is object declaration & instantiation?
15
www.infoviaan.com

16. Get in Touch
Thank You
www.infoviaan.com
16
www.infoviaan.com