The static keyword is used to construct methods that will exist regardless of whether or not any instances of the class are generated. Any method that uses the static keyword is referred to as a static method.
Features of static method:
- A static method in Java is a method that is part of a class rather than an instance of that class.
- Every instance of a class has access to the method.
- Static methods have access to class variables (static variables) without using the class’s object (instance).
- Only static data may be accessed by a static method. It is unable to access data that is not static (instance variables).
- In both static and non-static methods, static methods can be accessed directly.
Syntax to declare the static method:
Access_modifier static void methodName()
{
// Method body.
}
The name of the class can be used to invoke or access static methods.
Syntax to call a static method:
className.methodName();
Example 1: The static method does not have access to the instance variable
The JVM runs the static method first, followed by the creation of class instances. Because no objects are accessible when the static method is used. A static method does not have access to instance variables. As a result, a static method can’t access a class’s instance variable.
Java
// Java program to demonstrate that// The static method does not have// access to the instance variable import java.io.*; public class GFG { // static variable static int a = 40; // instance variable int b = 50; void simpleDisplay() { System.out.println(a); System.out.println(b); } // Declaration of a static method. static void staticDisplay() { System.out.println(a); } // main method public static void main(String[] args) { GFG obj = new GFG(); obj.simpleDisplay(); // Calling static method. staticDisplay(); }} |
40 50 40
Example 2: In both static and non-static methods, static methods are directly accessed.
Java
// Java program to demonstrate that// In both static and non-static methods,// static methods are directly accessed. import java.io.*; public class StaticExample { static int num = 100; static String str = "GeeksForGeeks"; // This is Static method static void display() { System.out.println("static number is " + num); System.out.println("static string is " + str); } // non-static method void nonstatic() { // our static method can accessed // in non static method display(); } // main method public static void main(String args[]) { StaticExample obj = new StaticExample(); // This is object to call non static function obj.nonstatic(); // static method can called // directly without an object display(); }} |
static number is 100 static string is GeeksForGeeks static number is 100 static string is GeeksForGeeks
Why use Static Methods?
- To access and change static variables and other non-object-based static methods.
- Utility and assist classes frequently employ static methods.
Restrictions in Static Methods:
- Non-static data members or non-static methods cannot be used by static methods, and static methods cannot call non-static methods directly.
- In a static environment, this and super aren’t allowed to be used.
Why is the main method in Java static?
It’s because calling a static method isn’t needed of the object. If it were a non-static function, JVM would first build an object before calling the main() method, resulting in an extra memory allocation difficulty.
Difference Between the static method and instance method
|
Instance Methods |
Static Methods |
|---|---|
| It requires an object of the class. | It doesn’t require an object of the class. |
| It can access all attributes of a class. | It can access only the static attribute of a class. |
| The methods can be accessed only using object reference. | The method is only accessed by class name. |
| Syntax: Objref.methodname() | Syntax: className.methodname() |
| It’s an example of pass-by-value programming. | It is an example of pass-by-reference programming. |
