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---
category: swing
folder: DnDReorderList
title: TransferHandlerを使ったJListのドラッグ&ドロップによる並べ替え
tags: [JList, TransferHandler, DragAndDrop]
author: aterai
pubdate: 2008-09-29T13:33:14+09:00
description: JListのアイテムを複数選択し、ドラッグ&ドロップで並べ替えを可能にするTransferHandlerを作成します。
image: https://lh4.googleusercontent.com/_9Z4BYR88imo/TQTLeSCyHuI/AAAAAAAAAXo/v2OLiSPdgEY/s800/DnDReorderList.png
---
* 概要 [#summary]
`JList`のアイテムを複数選択し、ドラッグ&ドロップで並べ替えを可能にする`TransferHandler`を作成します。

#download(https://lh4.googleusercontent.com/_9Z4BYR88imo/TQTLeSCyHuI/AAAAAAAAAXo/v2OLiSPdgEY/s800/DnDReorderList.png)

* サンプルコード [#sourcecode]
#code(link){{
class ListItemTransferHandler extends TransferHandler {
  private final DataFlavor localObjectFlavor;
  private Object[] transferedObjects = null;
  public ListItemTransferHandler() {
    localObjectFlavor = new DataFlavor(
      Object[].class, "Array of items");
  protected final DataFlavor localObjectFlavor;
  protected int[] indices;
  protected int addIndex = -1; // Location where items were added
  protected int addCount; // Number of items added.

  protected ListItemTransferHandler() {
    super();
    localObjectFlavor = new DataFlavor(List.class, "List of items");
  }
  @Override protected Transferable createTransferable(JComponent c) {
    JList list = (JList) c;
    indices = list.getSelectedIndices();
    transferedObjects = list.getSelectedValues();
    JList<?> source = (JList<?>) c;
    indices = source.getSelectedIndices();
    List<?> transferedObjects = source.getSelectedValuesList();
    return new Transferable() {
      @Override public DataFlavor[] getTransferDataFlavors() {
        return new DataFlavor[] {FLAVOR};
        return new DataFlavor[] {localObjectFlavor};
      }
      @Override public boolean isDataFlavorSupported(DataFlavor flavor) {
        return Objects.equals(FLAVOR, flavor);
        return Objects.equals(localObjectFlavor, flavor);
      }
      @Override public Object getTransferData(DataFlavor flavor)
            throws UnsupportedFlavorException, IOException {
          throws UnsupportedFlavorException, IOException {
        if (isDataFlavorSupported(flavor)) {
          return nodes;
          return transferedObjects;
        } else {
          throw new UnsupportedFlavorException(flavor);
        }
      }
    };
  }
  @Override public boolean canImport(TransferSupport info) {
    if (!info.isDrop() || !info.isDataFlavorSupported(localObjectFlavor)) {
      return false;
    }
    return true;
    return info.isDrop() && info.isDataFlavorSupported(localObjectFlavor);
  }
  @Override public int getSourceActions(JComponent c) {
    return TransferHandler.MOVE; //TransferHandler.COPY_OR_MOVE;
    return TransferHandler.MOVE; // TransferHandler.COPY_OR_MOVE;
  }
  @Override public boolean importData(TransferSupport info) {
    if (!canImport(info)) {
  @SuppressWarnings("unchecked")
  @Override public boolean importData(TransferHandler.TransferSupport info) {
    TransferHandler.DropLocation tdl = info.getDropLocation();
    if (!canImport(info) || !(tdl instanceof JList.DropLocation)) {
      return false;
    }
    JList target = (JList) info.getComponent();
    JList.DropLocation dl = (JList.DropLocation) info.getDropLocation();
    JList.DropLocation dl = (JList.DropLocation) tdl;
    JList<?> target = (JList<?>) info.getComponent();
    DefaultListModel listModel = (DefaultListModel) target.getModel();
    // boolean insert = dl.isInsert();
    int max = listModel.getSize();
    int index = dl.getIndex();
    //boolean insert = dl.isInsert();
    int max = listModel.getSize();
    if (index < 0 || index > max) {
      index = max;
    }
    // If it is out of range, it is appended to the end
    index = index < 0 ? max : index;
    index = Math.min(index, max);
    addIndex = index;

    try {
      Object[] values =
        (Object[]) info.getTransferable().getTransferData(localObjectFlavor);
      addCount = values.length;
      for (int i = 0; i < values.length; i++) {
        int idx = index++;
        listModel.add(idx, values[i]);
        target.addSelectionInterval(idx, idx);
      List<?> values = (List<?>) info.getTransferable()
        .getTransferData(localObjectFlavor);
      for (Object o : values) {
        int i = index++;
        listModel.add(i, o);
        target.addSelectionInterval(i, i);
      }
      addCount = values.size();
      return true;
    } catch (UnsupportedFlavorException | IOException ex) {
      ex.printStackTrace();
    }
    return false;
  }
  @Override protected void exportDone(
      JComponent c, Transferable data, int action) {
    cleanup(c, action == TransferHandler.MOVE);
  }
  private void cleanup(JComponent c, boolean remove) {
    if (remove && indices != null) {
      JList source = (JList) c;
      DefaultListModel model  = (DefaultListModel) source.getModel();
    if (remove && Objects.nonNull(indices)) {
      // If we are moving items around in the same list, we
      // need to adjust the indices accordingly, since those
      // after the insertion point have moved.
      if (addCount > 0) {
        for (int i = 0; i < indices.length; i++) {
          if (indices[i] >= addIndex) {
            indices[i] += addCount;
          }
        }
      }
      JList<?> source = (JList<?>) c;
      DefaultListModel model = (DefaultListModel) source.getModel();
      for (int i = indices.length - 1; i >= 0; i--) {
        model.remove(indices[i]);
      }
    }
    indices  = null;
    indices = null;
    addCount = 0;
    addIndex = -1;
  }
  private int[] indices = null;
  private int addIndex  = -1; //Location where items were added
  private int addCount  = 0;  //Number of items added.
}
}}

* 解説 [#explanation]
上記のサンプルの`TransferHandler`は、主に[https://docs.oracle.com/javase/tutorial/uiswing/examples/dnd/index.html#BasicDnD Drag and Drop and Data Transfer: Examples (The Java™ Tutorials > Creating a GUI with JFC/Swing > Drag and Drop and Data Transfer)]の[https://docs.oracle.com/javase/tutorial/uiswing/examples/dnd/DropDemoProject/src/dnd/ListTransferHandler.java ListTransferHandler.java]を参考にして作成しています。ただし、この`ListTransferHandler.java`は項目を複数選択して、`JList`内での並べ替えは想定していない(もしくはバグ?)ようなので、`importData(...)`メソッドや、`cleanup()`メソッドを修正しています。

#code{{
JList list = new JList(listModel);
list.getSelectionModel().setSelectionMode(ListSelectionModel.MULTIPLE_INTERVAL_SELECTION);
list.setTransferHandler(new ListItemTransferHandler());
list.setDropMode(DropMode.INSERT);
list.setDragEnabled(true);
}}

- `importData`
-- 使用されていない?`importString(...)`の内容をこちらに移動
- `cleanup`
-- 例えば、項目`0`,`1`,`2`を複数選択して、`1`と`2`の間にドロップすると、`1`,`2`,`2`になるので、以下のように修正
#code{{
for (int i = 0; i < indices.length; i++) {
  //if (indices[i] > addIndex) {
  // if (indices[i] > addIndex) {
  if (indices[i] >= addIndex) {
//...
// ...
}}

----
[[JListの項目をドラッグ&ドロップ>Swing/DnDList]]とは異なり、複数アイテムを選択して`Drag&Drop`による移動が可能になっています。

* 参考リンク [#reference]
- [https://docs.oracle.com/javase/tutorial/uiswing/examples/dnd/index.html#BasicDnD Drag and Drop and Data Transfer: Examples (The Java™ Tutorials > Creating a GUI with JFC/Swing > Drag and Drop and Data Transfer)]
-- [https://docs.oracle.com/javase/tutorial/uiswing/examples/dnd/DropDemoProject/src/dnd/ListTransferHandler.java ListTransferHandler.java]
- [[JListの項目をドラッグ&ドロップ>Swing/DnDList]]
- [[JListのアイテムをラバーバンドで複数選択、ドラッグ&ドロップで並べ替え>Swing/DragSelectDropReordering]]

* コメント [#comment]
#comment
- 複数選択して選択されたアイテムのインデックスに移動した場合、複写されるバグ?を修正。 -- &user(aterai); &new{2008-10-10 (金) 21:44:34};

#comment