Java - cannot be referenced from a static context

Question

Here's my simple class:

public class Project {
    private int size;
    private Obj tree;
    static Obj insert( Obj t, String s ) { // t is null
        t = new Obj();
        t.val = s;
        return t;
    }
    public Project()
    {
      Obj tree = new Obj();
      int size=0;
    }
    public class Obj
    {
      public String val;
      public Obj()
      {
        val=null;
      }
    }     
}

However, when I try to create a new object in the insert() function, I get this error:

Error: non-static variable this cannot be referenced from a static context

rgettman · Accepted Answer · 2015-03-18 23:51:50Z

6

Your Obj class is not static == it's an inner class. This means that it needs an instance of the enclosing class Project to live.

From the static method insert, there is no such Project instance, hence the compiler error.

The Obj class doesn't seem to need any instance variables in Project, so there is no reason to keep it non-static. Make the Obj class static in Project.

public static class Obj

answered Mar 18, 2015 at 23:51

rgettman

179k30 gold badges282 silver badges365 bronze badges

Sign up to request clarification or add additional context in comments.

1 Comment

Firkamon Over a year ago

Aha, thank you a lot. I'll mark your answer when I can.

Collectives™ on Stack Overflow

Java - cannot be referenced from a static context

1 Answer 1

1 Comment

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

1 Answer 1

1 Comment

Your Answer

Sign up or log in

Post as a guest

Related