| /* |
| * Copyright (c) 2003, 2006, 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 com.sun.jmx.remote.internal; |
| |
| import java.util.AbstractList; |
| import java.util.Iterator; |
| |
| public class ArrayQueue<T> extends AbstractList<T> { |
| public ArrayQueue(int capacity) { |
| this.capacity = capacity + 1; |
| this.queue = newArray(capacity + 1); |
| this.head = 0; |
| this.tail = 0; |
| } |
| |
| public void resize(int newcapacity) { |
| int size = size(); |
| if (newcapacity < size) |
| throw new IndexOutOfBoundsException("Resizing would lose data"); |
| newcapacity++; |
| if (newcapacity == this.capacity) |
| return; |
| T[] newqueue = newArray(newcapacity); |
| for (int i = 0; i < size; i++) |
| newqueue[i] = get(i); |
| this.capacity = newcapacity; |
| this.queue = newqueue; |
| this.head = 0; |
| this.tail = size; |
| } |
| |
| @SuppressWarnings("unchecked") |
| private T[] newArray(int size) { |
| return (T[]) new Object[size]; |
| } |
| |
| public boolean add(T o) { |
| queue[tail] = o; |
| int newtail = (tail + 1) % capacity; |
| if (newtail == head) |
| throw new IndexOutOfBoundsException("Queue full"); |
| tail = newtail; |
| return true; // we did add something |
| } |
| |
| public T remove(int i) { |
| if (i != 0) |
| throw new IllegalArgumentException("Can only remove head of queue"); |
| if (head == tail) |
| throw new IndexOutOfBoundsException("Queue empty"); |
| T removed = queue[head]; |
| queue[head] = null; |
| head = (head + 1) % capacity; |
| return removed; |
| } |
| |
| public T get(int i) { |
| int size = size(); |
| if (i < 0 || i >= size) { |
| final String msg = "Index " + i + ", queue size " + size; |
| throw new IndexOutOfBoundsException(msg); |
| } |
| int index = (head + i) % capacity; |
| return queue[index]; |
| } |
| |
| public int size() { |
| // Can't use % here because it's not mod: -3 % 2 is -1, not +1. |
| int diff = tail - head; |
| if (diff < 0) |
| diff += capacity; |
| return diff; |
| } |
| |
| private int capacity; |
| private T[] queue; |
| private int head; |
| private int tail; |
| } |