001/* 002 * Licensed to the Apache Software Foundation (ASF) under one or more 003 * contributor license agreements. See the NOTICE file distributed with 004 * this work for additional information regarding copyright ownership. 005 * The ASF licenses this file to You under the Apache License, Version 2.0 006 * (the "License"); you may not use this file except in compliance with 007 * the License. You may obtain a copy of the License at 008 * 009 * http://www.apache.org/licenses/LICENSE-2.0 010 * 011 * Unless required by applicable law or agreed to in writing, software 012 * distributed under the License is distributed on an "AS IS" BASIS, 013 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 014 * See the License for the specific language governing permissions and 015 * limitations under the License. 016 */ 017package org.apache.wicket.util.lang; 018 019import java.util.ArrayList; 020import java.util.HashMap; 021import java.util.Iterator; 022import java.util.concurrent.ConcurrentHashMap; 023 024/** 025 * Generics related utilities 026 * 027 * @author igor.vaynberg 028 */ 029public class Generics 030{ 031 private Generics() 032 { 033 034 } 035 036 /** 037 * Silences generics warning when need to cast iterator types 038 * 039 * @param <T> 040 * @param delegate 041 * @return <code>delegate</code> iterator cast to proper generics type 042 */ 043 @SuppressWarnings("unchecked") 044 public static <T> Iterator<T> iterator(final Iterator<?> delegate) 045 { 046 return (Iterator<T>)delegate; 047 } 048 049 /** 050 * Creates a new HashMap 051 * 052 * @param <K> 053 * @param <V> 054 * @return new hash map 055 */ 056 public static <K, V> HashMap<K, V> newHashMap() 057 { 058 return new HashMap<>(); 059 } 060 061 /** 062 * Creates a new HashMap 063 * 064 * @param <K> 065 * @param <V> 066 * @param capacity 067 * initial capacity 068 * @return new hash map 069 */ 070 public static <K, V> HashMap<K, V> newHashMap(final int capacity) 071 { 072 return new HashMap<>(capacity); 073 } 074 075 /** 076 * Creates a new ArrayList 077 * 078 * @param <T> 079 * @param capacity 080 * initial capacity 081 * @return array list 082 */ 083 public static <T> ArrayList<T> newArrayList(final int capacity) 084 { 085 return new ArrayList<>(capacity); 086 } 087 088 /** 089 * Creates a new ArrayList 090 * 091 * @param <T> 092 * @return array list 093 */ 094 public static <T> ArrayList<T> newArrayList() 095 { 096 return new ArrayList<>(); 097 } 098 099 /** 100 * Creates a new ConcurrentHashMap 101 * 102 * @param <K> 103 * @param <V> 104 * @return new hash map 105 */ 106 public static <K, V> ConcurrentHashMap<K, V> newConcurrentHashMap() 107 { 108 return new ConcurrentHashMap<>(); 109 } 110 111 /** 112 * Creates a new ConcurrentHashMap 113 * 114 * @param <K> 115 * @param <V> 116 * @param initialCapacity 117 * initial capacity 118 * @return new hash map 119 */ 120 public static <K, V> ConcurrentHashMap<K, V> newConcurrentHashMap(final int initialCapacity) 121 { 122 return new ConcurrentHashMap<>(initialCapacity); 123 } 124 125 126}