TypeAdaptingList.java

import java.util.*;

/**
 * List implementation that facilitates wrapping an existing list to convert the contents to another type.
 *
 * <pre>
 *     List<String> stringList = Arrays.asList("0", "1", "2", "3", "4");
 *     List<Integer> integerList = new TypeAdaptingList<Integer, String>() {
 *         Integer adapt(String value) {
 *             return Integer.parseInt(value);
 *         }
 *     };
 * </pre>
 *
 * @param <T> The type to adapt to.
 * @param <U> The type to adapt from.
 */
public abstract class TypeAdaptingList<T,U> extends AbstractList<T> {
    private List<U> toAdapt;

    /**
     * Constructs a new adapting list, converting the given list of type U to instances of T.
     *
     * @param toAdapt The list to adapt.
     */
    public TypeAdaptingList(List<U> toAdapt) {
        this.toAdapt = toAdapt;
    }

    @Override
    public T get(int index) {
        return adapt(toAdapt.get(index));
    }

    @Override
    public int size() {
        return toAdapt.size();
    }

    /**
     * Adapting method to convert instances of type U to instances of type T.
     *
     * @param value The value of type U to be adapted.
     * @return The adapted value of type T.
     */
    public abstract T adapt(U value);
}