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.*;
020
021 import org.fest.assertions.internal.PropertySupport;
022 import org.fest.util.*;
023
024 /**
025 * Extracts the values of an specified property from the elements of a given <code>{@link Collection}</code> or array.
026 *
027 * @author Yvonne Wang
028 */
029 public class Properties {
030
031 @VisibleForTesting final String propertyName;
032
033 @VisibleForTesting PropertySupport propertySupport = PropertySupport.instance();
034
035 /**
036 * Creates a new <code>{@link Properties}</code>.
037 * @param propertyName the name of the property to be read from the elements of a {@code Collection}. It may be a
038 * nested property (e.g. "address.street.number").
039 * @throws NullPointerException if the given property name is {@code null}.
040 * @throws IllegalArgumentException if the given property name is empty.
041 * @return the created {@code Properties}.
042 */
043 public static Properties extractProperty(String propertyName) {
044 checkIsNotNullOrEmpty(propertyName);
045 return new Properties(propertyName);
046 }
047
048 private static void checkIsNotNullOrEmpty(String propertyName) {
049 if (propertyName == null) throw new NullPointerException("The name of the property to read should not be null");
050 if (propertyName.length() == 0)
051 throw new IllegalArgumentException("The name of the property to read should not be empty");
052 }
053
054 @VisibleForTesting Properties(String propertyName) {
055 this.propertyName = propertyName;
056 }
057
058 /**
059 * Extracts the values of the property (specified previously in <code>{@link #extractProperty(String)}</code>) from
060 * the elements of the given <code>{@link Collection}</code>.
061 * @param c the given {@code Collection}.
062 * @return the values of the previously specified property extracted from the given {@code Collection}.
063 * @throws IntrospectionError if an element in the given {@code Collection} does not have a property with a matching
064 * name.
065 */
066 public List<?> from(Collection<?> c) {
067 return propertySupport.propertyValues(propertyName, c);
068 }
069
070 /**
071 * Extracts the values of the property (specified previously in <code>{@link #extractProperty(String)}</code>) from
072 * the elements of the given array.
073 * @param array the given array.
074 * @return the values of the previously specified property extracted from the given array.
075 * @throws IntrospectionError if an element in the given array does not have a property with a matching name.
076 */
077 public List<?> from(Object[] array) {
078 return propertySupport.propertyValues(propertyName, wrap(array));
079 }
080 }