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Google HTTP Client Library for Java. Functionality that works on all supported Java platforms, including Java 7 (or higher) desktop (SE) and web (EE), Android, and Google App Engine.

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/*
 * Copyright (c) 2011 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.api.client.util;

import java.lang.reflect.Field;
import java.util.ArrayList;
import java.util.Map;
import java.util.concurrent.ConcurrentMap;

/**
 * Collects the array values of a key/value data object, writing the fields or map values only after
 * all values have been collected.
 *
 * 

The typical application for this is when parsing JSON or XML when the value type is known to * be an array. It stores the values in a collection during the parsing, and only when the parsing * of an object is finished does it convert the collection into an array and stores it. * *

Use {@link #put(String, Class, Object)} when the destination object is a map with string keys * and whose values accept an array of objects. Use {@link #put(Field, Class, Object)} when setting * the value of a field using reflection, assuming its type accepts an array of objects. One can * potentially use both {@code put} methods for example on an instance of {@link GenericData}. * *

Implementation is not thread-safe. For a thread-safe choice instead use an implementation of * {@link ConcurrentMap}. * * @since 1.4 * @author Yaniv Inbar */ public final class ArrayValueMap { /** Array values on a particular field. */ static class ArrayValue { /** Array component type. */ final Class componentType; /** Values to be stored in the array. */ final ArrayList values = new ArrayList(); /** @param componentType array component type */ ArrayValue(Class componentType) { this.componentType = componentType; } /** Creates a new array whose content matches that of the {@link #values}. */ Object toArray() { return Types.toArray(values, componentType); } /** * Adds a given value to the array, checking the given component type matches the previously * stored component type. */ void addValue(Class componentType, Object value) { Preconditions.checkArgument(componentType == this.componentType); values.add(value); } } /** Map from key name to its array values. */ private final Map keyMap = ArrayMap.create(); /** Map from field to its array values. */ private final Map fieldMap = ArrayMap.create(); /** Destination object whose fields must be set, or destination map whose values must be set. */ private final Object destination; /** * @param destination destination object whose fields must be set, or destination map whose values * must be set */ public ArrayValueMap(Object destination) { this.destination = destination; } /** * Sets the fields of the given object using the values collected during parsing of the object's * fields. */ public void setValues() { for (Map.Entry entry : keyMap.entrySet()) { @SuppressWarnings("unchecked") Map destinationMap = (Map) destination; destinationMap.put(entry.getKey(), entry.getValue().toArray()); } for (Map.Entry entry : fieldMap.entrySet()) { FieldInfo.setFieldValue(entry.getKey(), destination, entry.getValue().toArray()); } } /** * Puts an additional value for the given field, accumulating values on repeated calls on the same * field. * * @param field field * @param arrayComponentType array component type * @param value value */ public void put(Field field, Class arrayComponentType, Object value) { ArrayValueMap.ArrayValue arrayValue = fieldMap.get(field); if (arrayValue == null) { arrayValue = new ArrayValue(arrayComponentType); fieldMap.put(field, arrayValue); } arrayValue.addValue(arrayComponentType, value); } /** * Puts an additional value for the given key name, accumulating values on repeated calls on the * same key name. * * @param keyName key name * @param arrayComponentType array component type * @param value value */ public void put(String keyName, Class arrayComponentType, Object value) { ArrayValueMap.ArrayValue arrayValue = keyMap.get(keyName); if (arrayValue == null) { arrayValue = new ArrayValue(arrayComponentType); keyMap.put(keyName, arrayValue); } arrayValue.addValue(arrayComponentType, value); } }