How the compiler understands your Java class

I have the following static factory method that creates a list view out of an int array:

public class ListFactory {
  public static List<Integer> newInstance(final int[] numbers) {
	return new AbstractList<Integer>() {
	  @Override
	  public Integer get(int index) {
		return numbers[index];
	  }
	  @Override
	  public int size() {
		return numbers.length;
	  }
	};
  }
}

In “Effective Java”, Joshua Bloch mentioned this as an Adapter that allows an int array to be viewed as a list of Integer instances However, I remember that Adapter pattern uses composition and the instance of the anonymous list implementation should therefore use the int[] as a member field. To verify the hypothesis and understand how the class is understood by the compiler, one can use the following command:

> javac -d . -XD-printflat ListFactory.java

From the output, one can clearly understand how the final parameter is passed to the inner anonymous class implementation:

public class ListFactory {
    
    public ListFactory() {
        super();
    }
    
    public static List newInstance(final int[] numbers) {
        return new ListFactory$1(numbers);
    }
}

class ListFactory$1 extends AbstractList {
    /*synthetic*/ final int[] val$numbers;
    
    ListFactory$1(/*synthetic*/ final int[] val$numbers) {
        this.val$numbers = val$numbers;
        super();
    }
    
    @Override()
    public Integer get(int index) {
        return Integer.valueOf(val$numbers[index]);
    }
    
    @Override()
    public int size() {
        return val$numbers.length;
    }
    
    @Override()
    /*synthetic*/ public Object get(/*synthetic*/ int index) {
        return this.get(index);
    }
}

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