001package votorola.g.util; // Copyright 2011-2012, Michael Allan. Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Votorola Software"), to deal in the Votorola Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicence, and/or sell copies of the Votorola Software, and to permit persons to whom the Votorola Software is furnished to do so, subject to the following conditions: The preceding copyright notice and this permission notice shall be included in all copies or substantial portions of the Votorola Software. THE VOTOROLA SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE VOTOROLA SOFTWARE OR THE USE OR OTHER DEALINGS IN THE VOTOROLA SOFTWARE. 002 003import java.util.*; 004 005 006/** ArrayList utilities. 007 */ 008public final class ArrayListX 009{ 010 011 private ArrayListX() {} 012 013 014 015 /** An empty list (intended to be immutable). 016 */ 017 public static final ArrayList<?> EMPTY_LIST = new EmptyList(); 018 019 020 021 /** Returns the {@linkplain #EMPTY_LIST empty list}. 022 */ 023 @SuppressWarnings("unchecked") 024 public static <T> ArrayList<T> emptyList() { return (ArrayList<T>)EMPTY_LIST; } 025 026 027 028//// P r i v a t e /////////////////////////////////////////////////////////////////////// 029 030 031 private static final class EmptyList extends ArrayList<Object> // FIX, try harder to keep it empty 032 { 033 034 private Object readResolve() { return EMPTY_LIST; } // keep it a singleton 035 036 037 // - C o l l e c t i o n ---------------------------------------------------------- 038 039 040 public @Override boolean add( Object o ) { throw new UnsupportedOperationException(); } 041 042 043 public @Override int size() 044 { 045 assert super.size() == 0; 046 return 0; 047 } 048 049 } 050 051 052}