CODEWITHSUNDEEP
javaoopinheritance
stackoverflow
stackoverflow

Reputation: 19474

Java Inheritance: How to declare a static variable in Super and instantiate it in subclass

How would you declare a static variable in Super and instantiate it in subclass

Example

class A
{
  static Queue<String> myArray;

  public void doStuff()
  {
     myArray.add(someMethod.getStuff());
  } 

}
class B extends A
{
  myArray = new LinkedList<String>();

}

class C extends A
{
  myArray = new LinkedList<String>();

}

Obviously this doesnt work. But how would you go about declaring a variable; then doing some common functionality with the variable in the super class; Then making sure each subclass gets it own static LinkedList?

Upvotes: 0

Views: 449

Answers (3)

Nazar Merza
Nazar Merza

Reputation: 3454

Since, you have subclass-specific properties to manipulate, you can't do it in the superclass, and it is not logical to do it anyways. As was already mentioned, you can do something like this:

abstract class A {
      public abstract void doStuff();       
    }

class B extends A    {
  static List<String>myArray = new LinkedList<String>();

  public abstract void doStuff() {
      // do B stuff
  }

}

class C extends A  {
  static List<String>myArray = new LinkedList<String>();
  public abstract void doStuff() {
      // do C stuff
  }

}

Upvotes: 0

Rohit Jain
Rohit Jain

Reputation: 213331

Static variable is bound to a class rather than an instance. If you need a separate static variable for subclasses, you need to declare them in each of your subclasses.

Upvotes: 0

Louis Wasserman
Louis Wasserman

Reputation: 198221

You can't do stuff along these lines. The closest you can do is to have an abstract (non-static) method in the superclass and do some stuff with it.

But in general, you cannot force subclasses to do anything static, and you cannot access subclasses' static fields from a superclass like you're trying to do.

Upvotes: 5

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