001 /*
002 * Created on Feb 22, 2011
003 *
004 * Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except in compliance with
005 * 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 is distributed on
010 * an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the License for the
011 * specific language governing permissions and limitations under the License.
012 *
013 * Copyright @2011 the original author or authors.
014 */
015 package org.fest.assertions.groups;
016
017 import static org.fest.assertions.util.ArrayWrapperList.wrap;
018
019 import java.util.Collection;
020 import java.util.List;
021
022 import org.fest.assertions.internal.PropertySupport;
023 import org.fest.util.IntrospectionError;
024 import org.fest.util.VisibleForTesting;
025
026 /**
027 * Extracts the values of a specified property from the elements of a given <code>{@link Collection}</code> or array.
028 *
029 * @author Yvonne Wang
030 */
031 public class Properties {
032
033 @VisibleForTesting final String propertyName;
034
035 @VisibleForTesting PropertySupport propertySupport = PropertySupport.instance();
036
037 /**
038 * Creates a new <code>{@link Properties}</code>.
039 * @param propertyName the name of the property to be read from the elements of a {@code Collection}. It may be a
040 * nested property (e.g. "address.street.number").
041 * @throws NullPointerException if the given property name is {@code null}.
042 * @throws IllegalArgumentException if the given property name is empty.
043 * @return the created {@code Properties}.
044 */
045 public static Properties extractProperty(String propertyName) {
046 checkIsNotNullOrEmpty(propertyName);
047 return new Properties(propertyName);
048 }
049
050 private static void checkIsNotNullOrEmpty(String propertyName) {
051 if (propertyName == null) throw new NullPointerException("The name of the property to read should not be null");
052 if (propertyName.length() == 0)
053 throw new IllegalArgumentException("The name of the property to read should not be empty");
054 }
055
056 @VisibleForTesting Properties(String propertyName) {
057 this.propertyName = propertyName;
058 }
059
060 /**
061 * Extracts the values of the property (specified previously in <code>{@link #extractProperty(String)}</code>) from
062 * the elements of the given <code>{@link Collection}</code>.
063 * @param c the given {@code Collection}.
064 * @return the values of the previously specified property extracted from the given {@code Collection}.
065 * @throws IntrospectionError if an element in the given {@code Collection} does not have a property with a matching
066 * name.
067 */
068 public List<?> from(Collection<?> c) {
069 return propertySupport.propertyValues(propertyName, c);
070 }
071
072 /**
073 * Extracts the values of the property (specified previously in <code>{@link #extractProperty(String)}</code>) from
074 * the elements of the given array.
075 * @param array the given array.
076 * @return the values of the previously specified property extracted from the given array.
077 * @throws IntrospectionError if an element in the given array does not have a property with a matching name.
078 */
079 public List<?> from(Object[] array) {
080 return propertySupport.propertyValues(propertyName, wrap(array));
081 }
082 }