Java Program to Check the Accessibility of an Instance variable by a Static Method

A static method belongs to the class rather than the object of a class. It can be invoked without the need for creating an instance of a class. It can access static data member and can change the value of it.

The static keyword is a non – access modifier in Java which can be used for variables, methods, and block of code. Static variables in Java belong to the class i.e it is initialized only once at the start of the execution. By using static variables a single copy is shared among all the instances of the class, and they can be accessed directly by class name and don’t require any instance. The Static method similarly belongs to the class and not the instance and it can access only static variables but not non-static variables. 

We cannot access non-static variables or instance variables inside a static method. Because a static method can be called even when no objects of the class have been instantiated.

Example 1:

Java

// Java Program to Check the Accessibility
// of an Instance variable by a Static Method

import java.io.*;

class GFG {

    // Instance variable
    public int k = 10;

    public static void main(String[] args)
    {

        // try to access instance variable a
        // but it's give us error
        System.out.print("value of a is: " + k);
    }
}

Output :

prog.java:16: error: non-static variable k cannot be referenced from a static context
        System.out.print("value of a is: " + k);
                                             ^
1 error

The instance variable, as the name suggests we need an instance of a class. We cannot access directly instance variables from a static method. Therefore, to access an instance variable, we must have an instance of the class from which we access the instance variable.

Example 2 :

Java

// Java Program to check accessibility of
// instance variables by static method

import java.io.*;

class GFG {

    // instance variable
    public int k;

    // Constructor to set value to instance variable
    public GFG(int k) { this.k = k; }

    // set method for instance variable
    public void setK() { this.k = k; }

    // get method for instance variable
    public int getK() { return k; }

    public static void main(String[] args)
    {

        // Calling class GFG where instance variable is
        // present
        GFG gfg = new GFG(10);

        // now we got instance of instance variable class
        // with help of this class we access instance
        // variable
        System.out.print("Value of k is: " + gfg.getK());
    }
}

Output

Value of k is: 10