java cannot make a static reference to the non-static method.txt

Question

Problem:

I tried to referring a variable using static reference implies to referring using the class name But, to access instance variables it is must to create an object, these are not available in the memory, before instantiation. Therefore, i cannot make static reference to non-static fields(variables) in Java. If i still, try to do so a compile time error is generated saying “non-static variable math cannot be referenced from a static contex.  My problem is given bellow:

public class StaticDemo {
    int i = 0;
    public static void main(String[] args) {
        System.out.println("in main method which is static");
        // Trying to access non-static field
        i = 5;
        // Trying to access non-static method
        instanceMethod();
    }
    
    public void instanceMethod(){
        System.out.println("Value of i- " + i);
    }
}

Can anyone givr me details about it, this would help me out

Answer 1

To make your program work, either you need to declare the instance variables static or, we should refer them using an object in the method you should try like this:

public class StaticDemo {
    int i = 0;
    public static void main(String[] args) {
        System.out.println("in main method which is static");
        StaticDemo obj = new StaticDemo();
        obj.i = 5;
        obj.instanceMethod();
    }
    
    public void instanceMethod(){
        System.out.println("Value of i- " + i);
    }
}