CODEWITHSUNDEEP
javaabstract-classmember-variables
btalb
btalb

Reputation: 7037

Java Access Abstract Instance variables

I have an abstract class with a variable like follows:

public abstract class MyAbstractClass {

    int myVariable = 1;

    protected abstract void FunctionThatUsesMyVariable();
}

Then when I go to instantiate my class through the following code, myVariable cannot be seen:

MyAbstractClass myClass = new MyAbstractClass() {

    @Override
    protected void FunctionThatUsesMyVariable() {
        // TODO Auto-generated method stub
    }
};

What am I doing wrong and how can I achieve what I am trying to achieve?

Upvotes: 2

Views: 12250

Answers (4)

dcernahoschi
dcernahoschi

Reputation: 15230

You are declaring myVariable as having package access and your 2 classes reside in different packages. Thus the variable is not visible to inheriting classes. You can declare it with protected access to be visible or put the 2 classes in the same package.

public abstract class MyAbstractClass {

    protected int myVariable = 1;

    protected abstract void FunctionThatUsesMyVariable();
}

Upvotes: 7

neutrino
neutrino

Reputation: 2317

Declare your variable as protected. It's package-private by default.

Upvotes: 1

OldCurmudgeon
OldCurmudgeon

Reputation: 65803

Seems to work for me:

public class Test {
  public static abstract class MyAbstractClass {
    int myVariable = 1;
    protected abstract void FunctionThatUsesMyVariable();
  }

  public void test() {
    MyAbstractClass myClass = new MyAbstractClass() {
      @Override
      protected void FunctionThatUsesMyVariable() {
        myVariable = 2;
      }
    };
  }

  public static void main(String args[]) {
    new Test().test();
  }
}

I suspect you are declaring the two classes in different packages. If that is what you want then you should make the variable protected (or public if you must). Alternatively - obviously - put them in the same package.

Upvotes: 2

Kafkaesque
Kafkaesque

Reputation: 1283

Because you're still subclassing/extending the abstract class and unless you make it protected, the field isn't inherited.

Upvotes: 1

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