实现一个包含不同值的TransformList？

Question

我尝试创建TransformList的实现，该实现维护源列表中的不同值列表。但是，我对实现应该如何将不同的值添加到内部包含的hashmap和distinct list中有点困惑。我认为我的ListChangeListener.change应该可行。但是，如何拦截任何新的或删除的不同值并将其添加/删除到不同的地图和列表？

public class DistinctList<E> extends TransformationList<E,E> {

    private final ObservableList<E> distinctList = FXCollections.observableArrayList();
    private final ConcurrentHashMap<E,E> distinctValues = new ConcurrentHashMap<>();
    private final ObservableList<E> source;

    public DistinctList(ObservableList<E> source) {
        super(source);
        this.source = source;
        source.stream().filter(s -> attemptAdd(s)).forEach(s -> distinctList.add(s));
    }
    private boolean attemptAdd(E e) {
        final boolean result = distinctValues.putIfAbsent(e,e) == null;
        if (result) {
            distinctList.add(e);
        }
        return result;
    }
    private boolean attemptRemove(E e) {
        final boolean result = distinctValues.remove(e, e);
        if (result) {
            distinctList.remove(e);
        }
        return result;
    }

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

            @Override
            public boolean wasAdded() {
                if (c.getAddedSubList().stream().filter(v -> distinctValues.contains(v) == false).findAny().isPresent()) {
                    return true;
                }
                else {
                    return false;
                }
            }

            @Override
            public boolean wasRemoved() {
                if (c.getRemoved().stream().filter(v -> !source.contains(v)).findAny().isPresent()) {
                    return true;
                }
                else {
                    return false;
                }
            }

            @Override
            public boolean wasPermutated() {
                return false;
            }


            @Override
            protected int[] getPermutation() {
                throw new AssertionError("getPermutation() not implemented");
            }

            @Override
            public List<E> getRemoved() {
                return c.getRemoved().stream().filter(v -> !source.contains(v)).collect(Collectors.toList());
            }

            @Override
            public int getFrom() {
                return 0;
            }

            @Override
            public int getTo() {
                return 0;
            }

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

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

    @Override
    public int getSourceIndex(int index) {
        return IntStream.range(0,source.size()).filter(i -> source.get(i).equals(this.get(i))).findAny().orElse(-1);
    }

    @Override
    public E get(int index) {
        return distinctList.get(index);
    }

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

更新

我一直在努力解决这个问题，我想我找到了将源更改与不同的值映射和列表进行交互的位置。但是当我的源列表删除一个值（并且其他具有相同hashcode / equals的值仍然存在）时，它会错误地从不同的值中删除该值。我做错了什么？

public class DistinctList<E> extends TransformationList<E,E> {

    private final ObservableList<E> distinctList = FXCollections.observableArrayList();
    private final ConcurrentHashMap<E,E> distinctValues = new ConcurrentHashMap<>();
    private final ObservableList<E> source;


    public DistinctList(ObservableList<E> source) {
        super(source);
        this.source = source;
        source.stream().forEach(s -> attemptAdd(s));
    }
    private boolean attemptAdd(E e) {
        final boolean result = distinctValues.putIfAbsent(e,e) == null;
        if (result) {
            distinctList.add(e);
        }
        return result;
    }
    private boolean attemptRemove(E e) {
        final boolean result = distinctValues.remove(e, e);
        if (result) {
            distinctList.remove(e);
        }
        return result;
    }

    @Override
    protected void sourceChanged(ListChangeListener.Change<? extends E> c) {
       ListChangeListener.Change<E> change = new ListChangeListener.Change<E>(this) {
            @Override
            public boolean wasAdded() {
                if (c.getAddedSubList().stream().filter(v -> source.contains(v)).findAny().isPresent()) {
                    return true;
                }
                else {
                    return false;
                }
            }

            @Override
            public boolean wasRemoved() {
                if (c.getRemoved().stream().filter(v -> source.contains(v) == false).findAny().isPresent()) {
                    return true;
                }
                else {
                    return false;
                }
            }

            @Override
            public boolean wasPermutated() {
                return false;
            }


            @Override
            protected int[] getPermutation() {
                throw new AssertionError("getPermutation() not implemented");
            }

            @Override
            public List<E> getRemoved() {
                return c.getRemoved().stream().filter(v -> source.contains(v) == false)
                        .collect(Collectors.toList());
            }

            @Override
            public int getFrom() {
                return 0;
            }

            @Override
            public int getTo() {
                return 0;
            }

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

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

        while (c.next()) {
            if (c.wasAdded()) {
                c.getAddedSubList().stream().filter(v -> !distinctValues.containsKey(v)).peek(a -> System.out.println("ADDING FROM MAP " + a)).forEach(a -> attemptAdd(a));
            }
            if (c.wasRemoved()) {
                c.getRemoved().stream().filter(v -> distinctValues.containsKey(v)).peek(a -> System.out.println("REMOVING FROM MAP " + a)).forEach(a -> attemptRemove(a));
            }
        }

        fireChange(change);
    }

    @Override
    public int getSourceIndex(int index) {
        return IntStream.range(0,source.size()).filter(i -> source.get(i).equals(this.get(i))).findAny().orElse(-1);
    }

    @Override
    public E get(int index) {
        return distinctList.get(index);
    }

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

Answer 1

我想我明白了。如果我遗失任何东西，请告诉我。

public class DistinctList<E> extends TransformationList<E,E> {

    private final ObservableList<E> distinctList = FXCollections.observableArrayList();
    private final ConcurrentHashMap<E,E> distinctValues = new ConcurrentHashMap<>();
    private final ObservableList<E> source;


    public DistinctList(ObservableList<E> source) {
        super(source);
        this.source = source;
        source.stream().forEach(s -> attemptAdd(s));
    }
    private boolean attemptAdd(E e) {
        final boolean result = distinctValues.putIfAbsent(e,e) == null;
        if (result) {
            distinctList.add(e);
        }
        return result;
    }
    private boolean attemptRemove(E e) {
        final boolean result = distinctValues.remove(e, e);
        if (result) {
            distinctList.remove(e);
        }
        return result;
    }

    @Override
    protected void sourceChanged(ListChangeListener.Change<? extends E> c) {

      while (c.next()) {
          ListChangeListener.Change<E> change = new ListChangeListener.Change<E>(this) {
              @Override
              public boolean wasAdded() {
                  if (c.getAddedSubList().stream().filter(v -> distinctValues.contains(v) == false).findAny().isPresent()) {
                      return true;
                  } else {
                      return false;
                  }
              }

              @Override
              public List<E> getAddedSubList() {
                return c.getAddedSubList().stream().filter(v -> distinctValues.contains(v) == false).collect(Collectors.toList());
              }

              @Override
              public boolean wasRemoved() {
                  if (c.getRemoved().stream().filter(v -> source.contains(v) == false).findAny().isPresent()) {
                      return true;
                  } else {
                      return false;
                  }
              }

              @Override
              public boolean wasPermutated() {
                  return false;
              }


              @Override
              protected int[] getPermutation() {
                  throw new AssertionError("getPermutation() not implemented");
              }

              @Override
              public List<E> getRemoved() {
                  return c.getRemoved().stream().filter(v -> source.contains(v) == false)
                          .collect(Collectors.toList());
              }

              @Override
              public int getFrom() {
                  return 0;
              }

              @Override
              public int getTo() {
                  return 0;
              }

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

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

          if (change.wasAdded()) {
              change.getAddedSubList().stream().filter(v -> !distinctValues.containsKey(v)).peek(a -> System.out.println("ADDING FROM MAP " + a)).forEach(a -> attemptAdd(a));
          }
          if (change.wasRemoved()) {
              change.getRemoved().stream().filter(v -> distinctValues.containsKey(v)).peek(a -> System.out.println("REMOVING FROM MAP " + a)).forEach(a -> attemptRemove(a));
          }
          fireChange(change);
      }

    }

    @Override
    public int getSourceIndex(int index) {
        return IntStream.range(0,source.size()).filter(i -> source.get(i).equals(this.get(i))).findAny().orElse(-1);
    }

    @Override
    public E get(int index) {
        return distinctList.get(index);
    }

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