001/* 002 * Copyright (C) 2007 The Guava Authors 003 * 004 * Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except 005 * in compliance with the License. You may obtain a copy of the License at 006 * 007 * http://www.apache.org/licenses/LICENSE-2.0 008 * 009 * Unless required by applicable law or agreed to in writing, software distributed under the License 010 * is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express 011 * or implied. See the License for the specific language governing permissions and limitations under 012 * the License. 013 */ 014 015package com.google.common.base; 016 017import static com.google.common.base.Preconditions.checkNotNull; 018 019import com.google.common.annotations.GwtIncompatible; 020import org.checkerframework.checker.nullness.qual.Nullable; 021 022/** 023 * This class provides default values for all Java types, as defined by the JLS. 024 * 025 * @author Ben Yu 026 * @since 1.0 027 */ 028@GwtIncompatible 029public final class Defaults { 030 private Defaults() {} 031 032 private static final Double DOUBLE_DEFAULT = Double.valueOf(0d); 033 private static final Float FLOAT_DEFAULT = Float.valueOf(0f); 034 035 /** 036 * Returns the default value of {@code type} as defined by JLS --- {@code 0} for numbers, {@code 037 * false} for {@code boolean} and {@code '\0'} for {@code char}. For non-primitive types and 038 * {@code void}, {@code null} is returned. 039 */ 040 @SuppressWarnings("unchecked") 041 public static <T> @Nullable T defaultValue(Class<T> type) { 042 checkNotNull(type); 043 if (type == boolean.class) { 044 return (T) Boolean.FALSE; 045 } else if (type == char.class) { 046 return (T) Character.valueOf('\0'); 047 } else if (type == byte.class) { 048 return (T) Byte.valueOf((byte) 0); 049 } else if (type == short.class) { 050 return (T) Short.valueOf((short) 0); 051 } else if (type == int.class) { 052 return (T) Integer.valueOf(0); 053 } else if (type == long.class) { 054 return (T) Long.valueOf(0L); 055 } else if (type == float.class) { 056 return (T) FLOAT_DEFAULT; 057 } else if (type == double.class) { 058 return (T) DOUBLE_DEFAULT; 059 } else { 060 return null; 061 } 062 } 063}