Static Variable, Methods and Block

Static

• The static keyword in Java is used for memory management mainly. 
• We can apply java static keyword with variables, methods, blocks and nested class. 
• The static keyword belongs to the class than an instance of the class.
• The static can be:

• Static Variable (also known as a class variable)

Example: static String college="AMPICS";

• Static Method (also known as a class method)
• If you apply a static keyword with any method, it is known as a static method.
• A static method belongs to the class rather than the object of a class.
• A static method can be invoked without the need for creating an instance of a class.
• A static method can access static data member and can change the value of it.
• Example:

static void change(){
     college = "GUNI-AMPICS";
     }

• Static Block
• It is used to initialize the static data member.
• It is executed before the main method at the time of classloading.
• Example:

static{
System.out.println("static block is invoked");
}

• Restrictions for the static method.
• The static method can not use nonstatic data member or call the non-static method directly.
• this and super cannot be used in static context.

• Why is the Java main method static?
• It is because the object is not required to call a static method.
• If it were a non-static method, JVM creates an object first then call main() method that will lead the problem of extra memory allocation.

Full Example:
class Counter2{
static int count=0;

Counter2()
{
count++;
System.out.println(count);
}

public static void main(String args[]){
Counter2 c1=new Counter2();
Counter2 c2=new Counter2();
Counter2 c3=new Counter2();
}
}