Java Programming Language Static Variable, Method And Nested Class

What is the use of static keyword in java?

Static keyword can be applied with variables, methods, blocks and nested class.

Static variables, methods and nested classes

A static method can be called without the need for creating an instance of a class. class name can be used to invoke the static variable and methods.

The static keyword in Java is used mainly for memory management.

The static variable can be used to refer the common property of all objects and it is not unique for each object.

Memory is allocated only once in class area at the time of class loading for static variables. It makes your program memory efficient (it saves memory).

Java Program to explain static variable, method and nested class

   class StaticExample
{  	
// memory is allocated only once and value is retained.
static int count=10; 
// static block
static 
{	
System.out.println("Static block is called first");  
}
// static nested class
static class Inner 
{	
static void msg()
{	
 System.out.println("msg method is called from static Inner class");
}
}
//A static method belongs to the class rather than object of a class.
//A static method can be called without the need for creating an instance of a class.
//static method can access static data member and can change the value of it.
static int add(int val1, int val2) 
{	
return val1+val2;
}
StaticExample()
{  	
count++;  
System.out.println(count);  
}  
int a=50; // non-static variable cannot be accessed by static method

public static void main(String args[])
{  
System.out.println(StaticExample.count); // static variable is called
StaticExample.Inner.msg();
int result= StaticExample.add(16, 16); // Static method is called
System.out.println(result);  
// Instance variable cannot be accessible inside static method.
//System.out.println(a);  // Compile time error

//this and super cannot be used in static context.
StaticExample obj1=new StaticExample(); 
StaticExample obj2=new StaticExample();     
}  
}