Swing/WheelCombo の変更点

---
category: swing
folder: WheelCombo
title: JComboBoxの値をMouseWheelで変更
tags: [JComboBox, MouseWheelListener]
author: aterai
pubdate: 2004-11-15T02:34:50+09:00
description: JComboBoxにフォーカスがある場合、その値をMouseWheelの上下で変更します。
image: https://lh4.googleusercontent.com/_9Z4BYR88imo/TQTWm95sa5I/AAAAAAAAApg/1tiQsmg5QKw/s800/WheelCombo.png
---
* Summary [#summary]
`JComboBox`にフォーカスがある場合、その値を`MouseWheel`の上下で変更します。

#download(https://lh4.googleusercontent.com/_9Z4BYR88imo/TQTWm95sa5I/AAAAAAAAApg/1tiQsmg5QKw/s800/WheelCombo.png)

* Source Code Examples [#sourcecode]
#code(link){{
JComboBox<String> combo = makeComboBox();
combo.addMouseWheelListener(new MouseWheelListener() {
  @Override public void mouseWheelMoved(MouseWheelEvent e) {
    JComboBox<?> source = (JComboBox<?>) e.getComponent();
    if (!source.hasFocus()) {
      return;
    }
    int ni = source.getSelectedIndex() + e.getWheelRotation();
    if (ni >= 0 && ni < source.getItemCount()) {
      source.setSelectedIndex(ni);
    }
  }
});
}}

* Description [#explanation]
* Description [#description]
上記のサンプルでは、`JComboBox`に`MouseWheelListener`を設定し`JComboBox`にフォーカスがある場合はマウスホイールの上下回転イベントに反応して表示内容を順次変更しています。

* Reference [#reference]
- [https://docs.oracle.com/javase/jp/8/docs/api/java/awt/event/MouseWheelListener.html MouseWheelListener (Java Platform SE 8)]

* Comment [#comment]
#comment
#comment