| /* |
| * Copyright 2011 Google Inc. |
| * |
| * Licensed under the Apache License, Version 2.0 (the "License"); |
| * you may not use this file except in compliance with the License. |
| * You may obtain a copy of the License at |
| * |
| * http://www.apache.org/licenses/LICENSE-2.0 |
| * |
| * Unless required by applicable law or agreed to in writing, software |
| * distributed under the License is distributed on an "AS IS" BASIS, |
| * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| * See the License for the specific language governing permissions and |
| * limitations under the License. |
| */ |
| |
| package com.google.ipc.invalidation.util; |
| |
| /** |
| * Container for a single arbitrary value. Useful when a nested callback needs |
| * to modify a primitive type, which is ordinarily not possible as variables |
| * available to nested callbacks need to be declared final. |
| * |
| * @param <T> Type of the value being boxed. |
| * |
| */ |
| public class Box<T> { |
| |
| /** Contents of the box. */ |
| private T value; |
| |
| /** Constructs a box with the given initial {@code value}. */ |
| public Box(T value) { |
| this.value = value; |
| } |
| |
| /** Constructs a Box with {@code null} as the value. */ |
| public Box() { |
| this.value = null; |
| } |
| |
| /** Constructs and returns a {@code Box} that wraps {@code objectValue}. */ |
| public static <T> Box<T> of(T objectValue) { |
| return new Box<T>(objectValue); |
| } |
| |
| public void set(T objectValue) { |
| this.value = objectValue; |
| } |
| |
| public T get() { |
| return value; |
| } |
| |
| @Override |
| public String toString() { |
| return (value == null) ? null : value.toString(); |
| } |
| } |