---
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
---
* Summary [#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)
* Source Code Examples [#sourcecode]
#code(link){{
class ListItemTransferHandler extends TransferHandler {
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<?> source = (JList<?>) c;
indices = source.getSelectedIndices();
List<?> transferredObjects = source.getSelectedValuesList();
return new Transferable() {
@Override public DataFlavor[] getTransferDataFlavors() {
return new DataFlavor[] {localObjectFlavor};
}
@Override public boolean isDataFlavorSupported(DataFlavor flavor) {
return Objects.equals(localObjectFlavor, flavor);
}
@Override public Object getTransferData(DataFlavor flavor)
throws UnsupportedFlavorException, IOException {
if (isDataFlavorSupported(flavor)) {
return transferredObjects;
} else {
throw new UnsupportedFlavorException(flavor);
}
}
};
}
@Override public boolean canImport(TransferSupport info) {
return info.isDrop() && info.isDataFlavorSupported(localObjectFlavor);
}
@Override public int getSourceActions(JComponent c) {
return TransferHandler.MOVE; // TransferHandler.COPY_OR_MOVE;
}
@SuppressWarnings("unchecked")
@Override public boolean importData(TransferHandler.TransferSupport info) {
TransferHandler.DropLocation tdl = info.getDropLocation();
if (!(tdl instanceof JList.DropLocation)) {
return false;
}
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();
// 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 {
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 && 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;
addCount = 0;
addIndex = -1;
}
}
}}
* Description [#explanation]
* Description [#description]
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(`0`が消えて`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) {
// ...
}}
----
[[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。
* Reference [#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]]
* Comment [#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