Mapped view of a JavaFX ObservableList.

LICENSE.md

To the extent possible under law, Tomas Mikula has waived all copyright and related or neighboring rights to this work.

MappedList.java

import java.util.ArrayList;
import java.util.List;
import java.util.function.Function;

import javafx.collections.ListChangeListener.Change;
import javafx.collections.ObservableList;
import javafx.collections.transformation.TransformationList;

public class MappedList<E, F> extends TransformationList<E, F> {

    private final Function<F, E> mapper;

    public MappedList(ObservableList<? extends F> source, Function<F, E> mapper) {
        super(source);
        this.mapper = mapper;
    }

    @Override
    public int getSourceIndex(int index) {
        return index;
    }

    @Override
    public E get(int index) {
        return mapper.apply(getSource().get(index));
    }

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

    @Override
    protected void sourceChanged(Change<? extends F> c) {
        fireChange(new Change<E>(this) {

            @Override
            public boolean wasAdded() {
                return c.wasAdded();
            }

            @Override
            public boolean wasRemoved() {
                return c.wasRemoved();
            }

            @Override
            public boolean wasReplaced() {
                return c.wasReplaced();
            }

            @Override
            public boolean wasUpdated() {
                return c.wasUpdated();
            }

            @Override
            public boolean wasPermutated() {
                return c.wasPermutated();
            }

            @Override
            public int getPermutation(int i) {
                return c.getPermutation(i);
            }

            @Override
            protected int[] getPermutation() {
                // This method is only called by the superclass methods
                // wasPermutated() and getPermutation(int), which are
                // both overriden by this class. There is no other way
                // this method can be called.
                throw new AssertionError("Unreachable code");
            }

            @Override
            public List<E> getRemoved() {
                ArrayList<E> res = new ArrayList<>(c.getRemovedSize());
                for(F e: c.getRemoved()) {
                    res.add(mapper.apply(e));
                }
                return res;
            }

            @Override
            public int getFrom() {
                return c.getFrom();
            }

            @Override
            public int getTo() {
                return c.getTo();
            }

            @Override
            public boolean next() {
                return c.next();
            }

            @Override
            public void reset() {
                c.reset();
            }
        });
    }
}

Suggested as an implementation for RT-35741

Interesting implementation of TransformationList. I actually need an implementation exactly like this, except I need the mapped values to be distinct. I'll have to struggle through that and use this as a starting point.

I started implementing the same thing and while debugging I found yours. Thanks!

Updated link for RT-35741: JDK-8091967 (The issue is still unresolved and categorized as tbd_major)

Hello Tomas, what is the license to use your code? Thanks!

Hi @rloschmann, I have added a license file with a link to CC0.

Hello Tomas, thanks a lot. I copied your code and added the missing implementation of int getViewIndex(int index).