Simon Hunt | 95d56fd | 2015-11-12 11:06:44 -0800 | [diff] [blame] | 1 | /* |
| 2 | * Copyright 2015 Open Networking Laboratory |
| 3 | * |
| 4 | * Licensed under the Apache License, Version 2.0 (the "License"); |
| 5 | * you may not use this file except in compliance with the License. |
| 6 | * You may obtain a copy of the License at |
| 7 | * |
| 8 | * http://www.apache.org/licenses/LICENSE-2.0 |
| 9 | * |
| 10 | * Unless required by applicable law or agreed to in writing, software |
| 11 | * distributed under the License is distributed on an "AS IS" BASIS, |
| 12 | * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| 13 | * See the License for the specific language governing permissions and |
| 14 | * limitations under the License. |
| 15 | */ |
| 16 | |
| 17 | package org.onlab.util; |
| 18 | |
| 19 | import java.util.HashMap; |
| 20 | |
| 21 | /** |
| 22 | * HashMap that returns a default value for unmapped keys. |
| 23 | */ |
Simon Hunt | 8f39cfb | 2015-11-16 09:12:09 -0800 | [diff] [blame] | 24 | public final class DefaultHashMap<K, V> extends HashMap<K, V> { |
Simon Hunt | 95d56fd | 2015-11-12 11:06:44 -0800 | [diff] [blame] | 25 | |
| 26 | /** Default value to return when no key binding exists. */ |
Simon Hunt | 8f39cfb | 2015-11-16 09:12:09 -0800 | [diff] [blame] | 27 | protected final V defaultValue; |
Simon Hunt | 95d56fd | 2015-11-12 11:06:44 -0800 | [diff] [blame] | 28 | |
| 29 | /** |
| 30 | * Constructs an empty map with the given default value. |
| 31 | * |
| 32 | * @param defaultValue the default value |
| 33 | */ |
| 34 | public DefaultHashMap(V defaultValue) { |
| 35 | this.defaultValue = defaultValue; |
| 36 | } |
| 37 | |
| 38 | @Override |
| 39 | public V get(Object k) { |
| 40 | return containsKey(k) ? super.get(k) : defaultValue; |
| 41 | } |
| 42 | } |