Java tutorial
//package com.java2s; /* * Copyright 2014 kohii. * * Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except * in compliance with the License. You may obtain a copy of the License at * * http://www.apache.org/licenses/LICENSE-2.0 * * Unless required by applicable law or agreed to in writing, software distributed under the License * is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express * or implied. See the License for the specific language governing permissions and limitations under * the License. */ import javax.swing.JScrollBar; public class Main { public static void scrollByBlock(JScrollBar scrollbar, int direction) { // This method is called from BasicScrollPaneUI to implement wheel // scrolling, and also from scrollByBlock(). int oldValue = scrollbar.getValue(); int blockIncrement = scrollbar.getBlockIncrement(direction); int delta = blockIncrement * ((direction > 0) ? +1 : -1); int newValue = oldValue + delta; // Check for overflow. if (delta > 0 && newValue < oldValue) { newValue = scrollbar.getMaximum(); } else if (delta < 0 && newValue > oldValue) { newValue = scrollbar.getMinimum(); } scrollbar.setValue(newValue); } }