Why non-static variable cannot be referenced from a static context?

"non-static variable cannot be referenced from a static context" is biggest nemesis of some one who has just

started programming and that too in Java. Since main method in java is most popular method among all beginners and

they try to put program code there they face "non-static variable cannot be referenced from a static context" compiler error when they  try to access a non static member variable inside main in Java which is static. if you want to know

why main is declared static in Java see the link.

public class StaticTest {

    private int count=0;

    public static void main(String args[]) throws IOException {

        count++; //compiler error: non-static variable count cannot be referenced from a static context

Why non static variable can not be called from static method

Now before finding answer of compiler error "non-static variable cannot be referenced from a static context", let's have a quick revision of static. Static variable in Java belongs to Class and its value remains same for all instance. static variable initialized when class is loaded into JVM on the other hand instance variable has different value for each instances and they get created when instance of an object is created either by using new() operator or using reflection like Class.newInstance(). So if you try to access a non static variable without any instance compiler will complain because those variables are not yet created and they don't have any existence until an instance is created and they are associated with any instance. So in my opinion only reason which make sense to disallow non static or instance variable inside static context is non existence of instance.

In summary since code in static context can be run even without creating any instance of class, it does not make sense asking value for an specific instance which is not yet created.

How to access non static variable inside static method or block

You can still access any non static variable inside any static method or block by creating an instance of class in Java

and using that instance to reference instance variable. This is the only legitimate way to access non static variable

on static context. here is a code example of accessing non static variable inside static context:

public class StaticTest {

    private int count=0;

    public static void main(String args[]) throws IOException {

        StaticTest test = new StaticTest(); //accessing static variable by creating an instance of class

        test.count++;

    }  

So next time if you get compiler error “non-static variable cannot be referenced from a static context” access static member by creating an instance of Class. Let me know if you find any other reason on why non-static variable cannot be referenced from a static context.

Other Java Tutorials you may find useful:

How to Convert String to Double in Java

How to Change Default pot of Tomcat

Ldap Authentication in Spring Security Tutorial and Example

How to Convert Date into mm/dd/yy format in Java

How to find current Date in Java with Example

Difference between fail-safe and fail-fast iterator in Java

Please share with your friends if like this article