/* * Copyright (c) 2003, 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 sun.misc; /** * Utility class for small LRU caches. * * @author Mark Reinhold */public abstract class LRUCache<N,V> {     private V[] oa = null;    private final int size;     public LRUCache(int size) {        this.size = size;    }     abstract protected V create(N name);     abstract protected boolean hasName(V ob, N name);     public static void moveToFront(Object[] oa, int i) {        Object ob = oa[i];        for (int j = i; j > 0; j--)            oa[j] = oa[j - 1];        oa[0] = ob;    }     public V forName(N name) {        if (oa == null) {            oa = (V[])new Object[size];        } else {            for (int i = 0; i < oa.length; i++) {                V ob = oa[i];                if (ob == null)                    continue;                if (hasName(ob, name)) {                    if (i > 0)                        moveToFront(oa, i);                    return ob;                }            }        }         // Create a new object        V ob = create(name);        oa[oa.length - 1] = ob;        moveToFront(oa, oa.length - 1);        return ob;    } }