this: Cannot use this in static context

Question

Can you please help me with below code. The error is: "Cannot use This in a static context"

public class Sample2 {
    /**
     * @param args
     */
    public static void main(String[] args) 
    {
        Sample2 sam=new Sample2();  

        //Below code works fine
        System.out.println(sam);

        //Below code is displaying error
        System.out.println(this);
    }
}

possible duplicate of [non-static variable cannot be referenced from a static context](http://stackoverflow.com/questions/2559527/non-static-variable-cannot-be-referenced-from-a-static-context) — Brian Roach, May 01 '13 at 09:13
possible duplicate of [why can't we use this keyword in a static method](http://stackoverflow.com/questions/11664522/why-cant-we-use-this-keyword-in-a-static-method) — fglez, May 07 '13 at 09:37

score 40 · Accepted Answer · answered May 01 '13 at 09:23

40

See, "this" keyword refers to current object due to which method is under exceution. As, you cannot call static method using instance of class. That is why, "this" can't be used in the above example in a static method as it is trying to print current instance wich is not at all created. So, I think thats why there is an compile time error that you are getting.

answered May 01 '13 at 09:23

Priyanka Vishwakarma

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Actually. you can call a static method by using an object of the class in which the static method has been declared. Compiler will give no error. We do not do this because its a very bad way of calling/using a static method. :) – Kaveesh Kanwal Feb 18 '15 at 15:41

score 18 · Answer 2 · edited May 23 '17 at 12:34

18

They keyword this refers to the instance of the class. In a static context, you have no instance, therefore you can't refer it.

For more information, refer to this answer: What is the meaning of "this" in Java?

edited May 23 '17 at 12:34

Community

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answered May 01 '13 at 09:10

Matten

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oh okay. I assumed that object reference of 'sam' would be available in 'this'. from the below answer, its clear that "this" keyword refers to current object due to which method is under execution" – Cyborgz May 02 '13 at 05:31

Suresh Atta · Answer 3 · 2013-05-01T09:15:03.723

3

In java you can not use this in static methods (static context).

Static methods do not point to any instance of the enclosing class.

A static method cannot refer to “this” or “super” keywords in anyway

Refer official docs on this keyword

edited May 01 '13 at 09:15

answered May 01 '13 at 09:09

Suresh Atta

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Vivek Vermani · Answer 4 · 2018-08-15T21:41:49.687

2

If we try to access this from a static context , compiler has no way to guess which instance, you are referring too. main is a static method here.

edited Aug 15 '18 at 21:41

answered Jun 05 '14 at 20:49

Vivek Vermani

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score 0 · Answer 5 · answered Dec 25 '18 at 13:31

writing this means in static context we are expecting to return the address of the object. Though its totally legal to have an object calling static methods but it is not an obligation. So compiler stops possibility of any error in case object is not created for the class.

this: Cannot use this in static context

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