1/*
2 * Copyright (C) 2007 Google Inc.
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
17package com.google.common.base;
18
19import java.util.HashMap;
20import java.util.Map;
21
22/**
23 * This class provides default values for all Java types, as defined by the JLS.
24 *
25 * @author Ben Yu
26 */
27public final class Defaults {
28  private Defaults() {}
29
30  private static final Map<Class<?>, Object> DEFAULTS =
31      new HashMap<Class<?>, Object>(16);
32
33  private static <T> void put(Class<T> type, T value) {
34    DEFAULTS.put(type, value);
35  }
36
37  static {
38    put(boolean.class, false);
39    put(char.class, '\0');
40    put(byte.class, (byte) 0);
41    put(short.class, (short) 0);
42    put(int.class, 0);
43    put(long.class, 0L);
44    put(float.class, 0f);
45    put(double.class, 0d);
46  }
47
48  /**
49   * Returns the default value of {@code type} as defined by JLS --- {@code 0}
50   * for numbers, {@code false} for {@code boolean} and {@code '\0'} for {@code
51   * char}. For non-primitive types and {@code void}, null is returned.
52   */
53  @SuppressWarnings("unchecked")
54  public static <T> T defaultValue(Class<T> type) {
55    return (T) DEFAULTS.get(type);
56  }
57}
58