JTreeのノードをドラッグ＆ドロップで並べ替える

概要

JTreeのノードをドラッグ＆ドロップで並べ替え可能なTransferHandlerを作成します。

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サンプルコード

class TreeTransferHandler extends TransferHandler {
  private final DataFlavor nodesFlavor = new DataFlavor(
      List.class, "List of TreeNode");

  @Override public int getSourceActions(JComponent c) {
    return c instanceof JTree
        && TreeUtils.canStartDrag((JTree) c) ? COPY_OR_MOVE : NONE;
  }

  @Override protected Transferable createTransferable(JComponent c) {
    Transferable transferable = null;
    if (c instanceof JTree && ((JTree) c).getSelectionPaths() != null) {
      List<MutableTreeNode> copies = new ArrayList<>();
      Arrays.stream(((JTree) c).getSelectionPaths()).forEach(path -> {
        DefaultMutableTreeNode node =
            (DefaultMutableTreeNode) path.getLastPathComponent();
        DefaultMutableTreeNode clone =
            new DefaultMutableTreeNode(node.getUserObject());
        copies.add(TreeUtils.deepCopy(node, clone));
      });
      transferable = new Transferable() {
        @Override public DataFlavor[] getTransferDataFlavors() {
          return new DataFlavor[] {nodesFlavor};
        }

        @Override public boolean isDataFlavorSupported(
            DataFlavor flavor) {
          return Objects.equals(nodesFlavor, flavor);
        }

        @Override public Object getTransferData(DataFlavor flavor)
            throws UnsupportedFlavorException {
          if (isDataFlavorSupported(flavor)) {
            return copies;
          } else {
            throw new UnsupportedFlavorException(flavor);
          }
        }
      };
    }
    return transferable;
  }

  @Override public boolean canImport(TransferSupport support) {
    DropLocation dl = support.getDropLocation();
    Component c = support.getComponent();
    return support.isDrop()
        && support.isDataFlavorSupported(nodesFlavor)
        && c instanceof JTree
        && dl instanceof JTree.DropLocation
        && TreeUtils.canImportDropLocation(
            (JTree) c, (JTree.DropLocation) dl);
  }

  @Override public boolean importData(TransferSupport support) {
    Component c = support.getComponent();
    DropLocation dl = support.getDropLocation();
    Transferable transferable = support.getTransferable();
    return canImport(support)
        && c instanceof JTree
        && dl instanceof JTree.DropLocation
        && insertNode((JTree) c, (JTree.DropLocation) dl, transferable);
  }

  private boolean insertNode(
      JTree tree, JTree.DropLocation dl, Transferable transferable) {
    TreePath path = dl.getPath();
    Object p = path.getLastPathComponent();
    TreeModel m = tree.getModel();
    List<?> nodes = getTransferData(transferable);
    if (p instanceof MutableTreeNode && m instanceof DefaultTreeModel) {
      MutableTreeNode parent = (MutableTreeNode) p;
      DefaultTreeModel model = (DefaultTreeModel) m;
      int childIndex = dl.getChildIndex();
      AtomicInteger index = new AtomicInteger(
          getDropIndex(parent, childIndex));
      nodes.stream()
          .filter(MutableTreeNode.class::isInstance)
          .map(MutableTreeNode.class::cast)
          .forEach(n -> model.insertNodeInto(
               n, parent, index.getAndIncrement()));
    }
    return !nodes.isEmpty();
  }

  private static int getDropIndex(
      MutableTreeNode parent, int childIndex) {
    // Configure for drop mode.
    int index = childIndex; // DropMode.INSERT
    if (childIndex == -1) { // DropMode.ON
      index = parent.getChildCount();
    }
    return index;
  }

  private List<?> getTransferData(Transferable t) {
    List<?> nodes;
    try {
      nodes = (List<?>) t.getTransferData(nodesFlavor);
    } catch (UnsupportedFlavorException | IOException ex) {
      nodes = Collections.emptyList();
    }
    return nodes;
  }

  @Override protected void exportDone(
      JComponent src, Transferable data, int action) {
    if (src instanceof JTree && (action & MOVE) == MOVE) {
      cleanup((JTree) src);
    }
  }

  private void cleanup(JTree tree) {
    DefaultTreeModel model = (DefaultTreeModel) tree.getModel();
    TreePath[] selectionPaths = tree.getSelectionPaths();
    if (selectionPaths != null) {
      for (TreePath path : selectionPaths) {
        model.removeNodeFromParent(
            (MutableTreeNode) path.getLastPathComponent());
      }
    }
  }
}

View in GitHub: Java, Kotlin

解説

TreeSelectionModel.CONTIGUOUS_TREE_SELECTIONを設定して複数の連続パス(選択範囲の項目は連続している)を選択可能に変更
TransferHandler.getCutAction().getValue(Action.NAME)キーで実行するアクションを空アクションに変更して、Ctrl-Xキーでのノードカットを無効化
TransferHandler#getSourceActions(...)をオーバーライドしてルートノード(ノードレベルが0)ではない、かつ選択されているノードはすべて兄弟ノード(ノードレベルが同じ)となる場合はドラッグ開始可能に設定

@Override public int getSourceActions(JComponent c) {
  return c instanceof JTree && TreeUtils.canStartDrag((JTree) c) ? MOVE : NONE;
}

public static boolean canStartDrag(JTree tree) {
  TreePath[] paths = tree.getSelectionPaths();
  return paths != null && canStartDragPaths(paths);
}

public static boolean canStartDragPaths(TreePath... paths) {
  return Arrays.stream(paths)
      .map(TreePath::getLastPathComponent)
      .filter(DefaultMutableTreeNode.class::isInstance)
      .map(DefaultMutableTreeNode.class::cast)
      .map(DefaultMutableTreeNode::getLevel)
      .distinct()
      .filter(level -> level != 0)
      .count() == 1;
}

TransferHandler#canImport(...)をオーバーライドしてドロップ先がドラッグ元の子孫ノードではない、かつドラッグ元の選択ノード範囲外の場合ドロップ可能に設定

@Override public boolean canImport(TransferSupport support) {
  DropLocation dl = support.getDropLocation();
  Component c = support.getComponent();
  return support.isDrop()
      && support.isDataFlavorSupported(nodesFlavor)
      && c instanceof JTree
      && dl instanceof JTree.DropLocation
      && TreeUtils.canImportDropLocation(
          (JTree) c, (JTree.DropLocation) dl);
}

public static boolean canImportDropLocation(
    JTree tree, JTree.DropLocation dl) {
  // Do not allow drop to descendant and drag-source selections
  // int dropRow = tree.getRowForPath(dl.getPath());
  Point pt = dl.getDropPoint();
  int dropRow = tree.getRowForLocation(pt.x, pt.y);
  int[] selRows = tree.getSelectionRows();
  return selRows != null && IntStream
      .of(selRows)
      .noneMatch(r -> r == dropRow || isDescendant(tree, r, dropRow));
}

private static boolean isDescendant(JTree tree, int selRow, int dropRow) {
  Object node = tree.getPathForRow(selRow).getLastPathComponent();
  return node instanceof DefaultMutableTreeNode
      && isDescendant2(tree, dropRow, (DefaultMutableTreeNode) node);
}

private static boolean isDescendant2(
    JTree tree, int dropRow, DefaultMutableTreeNode node) {
  Enumeration<?> e = node.depthFirstEnumeration();
  return Collections.list(e)
      .stream()
      .filter(DefaultMutableTreeNode.class::isInstance)
      .map(DefaultMutableTreeNode.class::cast)
      .map(DefaultMutableTreeNode::getPath)
      .map(TreePath::new)
      .map(tree::getRowForPath)
      .anyMatch(row -> row == dropRow);
  }

TransferHandler#importData(...)をオーバーライドしてDefaultTreeModel#insertNodeInto()でドラッグされた選択ノードをコピー
- JTreeのノードをドラッグ＆ドロップ
- JTree.DropLocation#getChildIndex()が-1になる場合はノード上にドロップ、それ以外の場合はノード間にドロップされる

@Override public boolean importData(TransferSupport support) {
  Component c = support.getComponent();
  DropLocation dl = support.getDropLocation();
  Transferable transferable = support.getTransferable();
  return canImport(support)
      && c instanceof JTree
      && dl instanceof JTree.DropLocation
      && insertNode((JTree) c, (JTree.DropLocation) dl, transferable);
}

private boolean insertNode(
    JTree tree, JTree.DropLocation dl, Transferable transferable) {
  TreePath path = dl.getPath();
  Object p = path.getLastPathComponent();
  TreeModel m = tree.getModel();
  List<?> nodes = getTransferData(transferable);
  if (p instanceof MutableTreeNode && m instanceof DefaultTreeModel) {
    MutableTreeNode parent = (MutableTreeNode) p;
    DefaultTreeModel model = (DefaultTreeModel) m;
    int childIndex = dl.getChildIndex();
    AtomicInteger index = new AtomicInteger(
        getDropIndex(parent, childIndex));
    nodes.stream()
        .filter(MutableTreeNode.class::isInstance)
        .map(MutableTreeNode.class::cast)
        .forEach(n -> model.insertNodeInto(
            n, parent, index.getAndIncrement()));
  }
  return !nodes.isEmpty();
}

private static int getDropIndex(MutableTreeNode parent, int childIndex) {
  // Configure for drop mode.
  int index = childIndex; // DropMode.INSERT
  if (childIndex == -1) { // DropMode.ON
    index = parent.getChildCount();
  }
  return index;
}

private List<?> getTransferData(Transferable t) {
  List<?> nodes;
  try {
    nodes = (List<?>) t.getTransferData(nodesFlavor);
  } catch (UnsupportedFlavorException | IOException ex) {
    nodes = Collections.emptyList();
  }
  return nodes;
}

TransferHandler#exportDone(...)をオーバーライドしてドロップアクションがMOVEの場合はドロップ元の選択ノードを削除
- Ctrlキーが押下されてドロップアクションがCOPYの場合はなにも実行しない

@Override protected void exportDone(
    JComponent src, Transferable data, int action) {
  if (src instanceof JTree && (action & MOVE) == MOVE) {
    cleanup((JTree) src);
  }
}

private void cleanup(JTree tree) {
  DefaultTreeModel model = (DefaultTreeModel) tree.getModel();
  TreePath[] selectionPaths = tree.getSelectionPaths();
  if (selectionPaths != null) {
    for (TreePath path : selectionPaths) {
      model.removeNodeFromParent(
          (MutableTreeNode) path.getLastPathComponent());
    }
  }
}

JTreeのノードをドラッグ＆ドロップで並べ替える

概要

Screenshot

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サンプルコード

解説

参考リンク

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