Static reference to non-static field Java error

Question

I'll preface this by saying that I've been a longtime fan of Stack Overflow, and over the past few semesters I've usually been able to find the answer to all my questions without actually asking one. However, I've been having problems with a stack program. There's more code than this, but I think I've narrowed my problem down to this one error. It states

Exception in thread "main" java.lang.Error: Unresolved compilation problems:

Cannot make a static reference to the non-static field Stack1
The constructor Stack(int) is undefined

at stack.main(stack.java:11)

Can anyone explain what the issue might be? Or better yet, point me to somewhere that will explain it? I've tried looking it up on Overflow and through google, but I think a combination of not knowing what I'm actually looking for and/or fatigue is preventing me from finding a concrete answer. Thanks for any help in advance.

public class stack {
private Object[] Stack1;
private int topOfStack;
private int max;
//private int empty;
//private int capacity;

public static void main(String[] args) {
Stack1 = new Stack(5);
    
}

public Stack(int size) {
    if (size < 0){
        throw new IllegalArgumentException("Parameter must be >0. Parameter was " + size + ".");
    }
    
    max = size; 
    Stack1 = (Object[]) (new Object[size]);
    topOfStack = -1;
}
   }

You need a little reorganization of your code. What is it you're trying to achieve? Do you just want to create a Stack object to have available? — Snowy Coder Girl, Oct 05 '11 at 03:29
Please fix your style and indentation! this is Java so class names should begin with an uppercase ("Stack" not "stack"), variable names and method names should begin with a lowercase ("stack1" not "Stack1"). Notice the colouring in the code here on SO - identifiers beginning with a capital are coloured differently because they are assumed to be types. — davmac, Oct 05 '11 at 03:36

score 1 · Accepted Answer · answered Oct 05 '11 at 03:21

1

Rename your class "Stack" (uppercase) and change the line:

Stack1 = new Stack(5)

to:

Stack stack1 = new Stack(5);

answered Oct 05 '11 at 03:21

Snowy Coder Girl

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so simple! I had tried Stack stack1 = new Stack(int) initially but changed it, only to see that the class name was wrong! So disappointed in myself. Thank you! – 1991DBA Oct 05 '11 at 03:59
No problem. We all have "Oh, duh" moments. Sometimes just takes another set of eyes ;) – Snowy Coder Girl Oct 05 '11 at 04:02

Bhesh Gurung · Answer 2 · 2011-10-05T03:31:26.347

1

In the following line -

private Object[] Stack1;

Stack1 is not static.

And in the following you are trying to refer to Stack1 -

public static void main(String[] args) {
    Stack1 = new Stack(5);
}

from within main which is static.

Thus -

Cannot make a static reference to the non-static field Stack1

Your constructor name is Stack which does not match class name is stack. So -

The constructor Stack(int) is undefined

May be, you want to name your class Stack and in your main the following -

public static void main(String[] args) {
    Stack stack1 = new Stack(5);
}

edited Oct 05 '11 at 03:31

answered Oct 05 '11 at 03:23

Bhesh Gurung

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You'll also need to change stack1 to not be an object array. – Snowy Coder Girl Oct 05 '11 at 03:28
@RachelG.: What should it be? – Bhesh Gurung Oct 05 '11 at 13:09
Nevermind. I was thinking you were setting the class variable "Stack1". Was an Object[] getting set to a Stack. But you created a new stack1 local variable. My bad. – Snowy Coder Girl Oct 05 '11 at 22:39

score 0 · Answer 3 · answered Oct 05 '11 at 03:05

0

Your class is declared as stack lowercase.

answered Oct 05 '11 at 03:05

K-ballo

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Michael McGowan · Answer 4 · 2011-10-05T03:31:29.243

0

Stack1 is in instance variable to the stack class. In your static main method, you try to store a value in the Stack1 variable even though it is an instance variable. Also, you try to assign a non-array type to a variable whose type is an array of Object. Furthermore, you have a constructor for Stack (note the uppercase) even though the class is called stack in lowercase.

edited Oct 05 '11 at 03:31

answered Oct 05 '11 at 03:09

Michael McGowan

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score 0 · Answer 5 · answered Oct 05 '11 at 03:12

0

Keeping the lower case class declaration, I'm guessing the assignment

   Stack1 = new Stack(5);

is not what you meant. Rather:

Stack1 stack = new stack(5);

answered Oct 05 '11 at 03:12

David J. Liszewski

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Static reference to non-static field Java error

5 Answers5