typeinfocollection.java

来自「地图生成的一个文件」· Java 代码 · 共 47 行

/*
 * 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.ParameterizedType;
import java.lang.reflect.Type;
import java.util.Collection;

/**
 * A convenience object for retrieving the map type information.
 *
 * @author Inderjeet Singh
 * @author Joel Leitch
 */
final class TypeInfoCollection {
  private final ParameterizedType collectionType;

  public TypeInfoCollection(Type collectionType) {
    if (!(collectionType instanceof ParameterizedType)) {
      throw new IllegalArgumentException(
          "Collection objects need to be parameterized unless you use a custom serializer. "
              + "Use the com.google.gson.reflect.TypeToken to extract the ParameterizedType.");
    }
    TypeInfo rawType = new TypeInfo(collectionType);
    Preconditions.checkArgument(Collection.class.isAssignableFrom(rawType.getRawClass()));
    this.collectionType = (ParameterizedType) collectionType;
  }

  public Type getElementType() {
    return collectionType.getActualTypeArguments()[0];
  }
}