/* * Copyright (C) 2008 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.gson;import java.lang.reflect.Array;import java.lang.reflect.GenericArrayType;import java.lang.reflect.ParameterizedType;import java.lang.reflect.Type;import java.lang.reflect.WildcardType;/** * Utility class containing some methods for obtaining information on types. * * @author Inderjeet Singh * @author Joel Leitch */final class TypeUtils {  /**   * Returns the actual type matching up with the first type variable.   * So, for a {@code typeInfo} instance defined as:   * <pre>   *   class Foo<A, B> {   *   }   *   Type fooType = new TypeToken<Foo<Integer, String>>() {}.getType();   * </pre>   * <code>TypeUtils.getActualTypeForFirstTypeVariable(fooType)</code> will return Integer.class.   */  static Type getActualTypeForFirstTypeVariable(Type type) {    if (type instanceof Class) {      return Object.class;    } else if (type instanceof ParameterizedType) {      return ((ParameterizedType)type).getActualTypeArguments()[0];    } else if (type instanceof GenericArrayType) {      return getActualTypeForFirstTypeVariable(((GenericArrayType)type).getGenericComponentType());    } else {      throw new IllegalArgumentException("Type \'" + type + "\' is not a Class, "          + "ParameterizedType, or GenericArrayType. Can't extract class.");    }  }  static boolean isArray(Type type) {    if (type instanceof Class) {      return ((Class<?>)type).isArray();    } else if (type instanceof GenericArrayType) {      return true;    } else {      return false;    }  }  /**   * This method returns the actual raw class associated with the specified type.   */  static Class<?> toRawClass(Type type) {    if (type instanceof Class) {      return (Class<?>) type;    } else if (type instanceof ParameterizedType) {      ParameterizedType actualType = (ParameterizedType)type;      return toRawClass(actualType.getRawType());    } else if (type instanceof GenericArrayType) {      GenericArrayType actualType = (GenericArrayType) type;      Class<?> rawClass = toRawClass(actualType.getGenericComponentType());      return wrapWithArray(rawClass);    } else if (type instanceof WildcardType) {      WildcardType castedType = (WildcardType) type;      return toRawClass(castedType.getUpperBounds()[0]);    } else {      throw new IllegalArgumentException("Type \'" + type + "\' is not a Class, "          + "ParameterizedType, or GenericArrayType. Can't extract class.");    }  }  static Class<?> wrapWithArray(Class<?> rawClass) {    return Array.newInstance(rawClass, 0).getClass();  }  private TypeUtils() {    // Class with just some static utility methods, should not be instantiated  }}