eaglercraft-1.8/sources/main/java/com/google/common/base/Defaults.java

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2022-12-25 01:12:28 -08:00
/*
* Copyright (C) 2007 The Guava Authors
*
* 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.common.base;
import static com.google.common.base.Preconditions.checkNotNull;
import java.util.Collections;
import java.util.HashMap;
import java.util.Map;
/**
* This class provides default values for all Java types, as defined by the JLS.
*
* @author Ben Yu
* @since 1.0
*/
public final class Defaults {
private Defaults() {
}
private static final Map<Class<?>, Object> DEFAULTS;
static {
// Only add to this map via put(Map, Class<T>, T)
Map<Class<?>, Object> map = new HashMap<Class<?>, Object>();
put(map, boolean.class, false);
put(map, char.class, '\0');
put(map, byte.class, (byte) 0);
put(map, short.class, (short) 0);
put(map, int.class, 0);
put(map, long.class, 0L);
put(map, float.class, 0f);
put(map, double.class, 0d);
DEFAULTS = Collections.unmodifiableMap(map);
}
private static <T> void put(Map<Class<?>, Object> map, Class<T> type, T value) {
map.put(type, value);
}
/**
* Returns the default value of {@code type} as defined by JLS --- {@code 0} for
* numbers, {@code
* false} for {@code boolean} and {@code '\0'} for {@code char}. For
* non-primitive types and {@code void}, null is returned.
*/
public static <T> T defaultValue(Class<T> type) {
// Primitives.wrap(type).cast(...) would avoid the warning, but we can't use
// that from here
@SuppressWarnings("unchecked") // the put method enforces this key-value relationship
T t = (T) DEFAULTS.get(checkNotNull(type));
return t;
}
}