/* * Copyright (c) 2001, 2008, Oracle and/or its affiliates. All rights reserved. * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. * * This code is free software; you can redistribute it and/or modify it * under the terms of the GNU General Public License version 2 only, as * published by the Free Software Foundation.  Oracle designates this * particular file as subject to the "Classpath" exception as provided * by Oracle in the LICENSE file that accompanied this code. * * This code is distributed in the hope that it will be useful, but WITHOUT * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License * version 2 for more details (a copy is included in the LICENSE file that * accompanied this code). * * You should have received a copy of the GNU General Public License version * 2 along with this work; if not, write to the Free Software Foundation, * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. * * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA * or visit www.oracle.com if you need additional information or have any * questions. */package javax.swing.text; import java.util.ArrayList;import java.util.List; /** * SegmentCache caches <code>Segment</code>s to avoid continually creating * and destroying of <code>Segment</code>s. A common use of this class would * be: * <pre> *   Segment segment = segmentCache.getSegment(); *   // do something with segment *   ... *   segmentCache.releaseSegment(segment); * </pre> * */class SegmentCache {    /**     * A global cache.     */    private static SegmentCache sharedCache = new SegmentCache();     /**     * A list of the currently unused Segments.     */    private List<Segment> segments;      /**     * Returns the shared SegmentCache.     */    public static SegmentCache getSharedInstance() {        return sharedCache;    }     /**     * A convenience method to get a Segment from the shared     * <code>SegmentCache</code>.     */    public static Segment getSharedSegment() {        return getSharedInstance().getSegment();    }     /**     * A convenience method to release a Segment to the shared     * <code>SegmentCache</code>.     */    public static void releaseSharedSegment(Segment segment) {        getSharedInstance().releaseSegment(segment);    }       /**     * Creates and returns a SegmentCache.     */    public SegmentCache() {        segments = new ArrayList<Segment>(11);    }     /**     * Returns a <code>Segment</code>. When done, the <code>Segment</code>     * should be recycled by invoking <code>releaseSegment</code>.     */    public Segment getSegment() {        synchronized(this) {            int size = segments.size();             if (size > 0) {                return segments.remove(size - 1);            }        }        return new CachedSegment();    }     /**     * Releases a Segment. You should not use a Segment after you release it,     * and you should NEVER release the same Segment more than once, eg:     * <pre>     *   segmentCache.releaseSegment(segment);     *   segmentCache.releaseSegment(segment);     * </pre>     * Will likely result in very bad things happening!     */    public void releaseSegment(Segment segment) {        if (segment instanceof CachedSegment) {            synchronized(this) {                segment.array = null;                segment.count = 0;                segments.add(segment);            }        }    }      /**     * CachedSegment is used as a tagging interface to determine if     * a Segment can successfully be shared.     */    private static class CachedSegment extends Segment {    }}