Converts array into a java.util.Map. : Array Collections « Collections Data Structure « Java
Converts array into a java.util.Map.
import java.util.HashMap;
import java.util.Map;
/*
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership.
* The ASF licenses this file to You 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.
*
*
*/
/**
* @author Stephen Colebourne
* @author Moritz Petersen
* @author <a href="mailto:fredrik@westermarck.com">Fredrik Westermarck</a>
* @author Nikolay Metchev
* @author Matthew Hawthorne
* @author Tim O'Brien
* @author Pete Gieser
* @author Gary Gregory
* @author <a href="mailto:equinus100@hotmail.com">Ashwin S</a>
* @author Maarten Coene
* @since 2.0
* @version $Id: ArrayUtils.java 632503 2008-03-01 00:21:52Z ggregory $
*/
public class Main {
// To map
//-----------------------------------------------------------------------
/**
* <p>Converts the given array into a {@link java.util.Map}. Each element of the array
* must be either a {@link java.util.Map.Entry} or an Array, containing at least two
* elements, where the first element is used as key and the second as
* value.</p>
*
* <p>This method can be used to initialize:</p>
* <pre>
* // Create a Map mapping colors.
* Map colorMap = MapUtils.toMap(new String[][] {{
* {"RED", "#FF0000"},
* {"GREEN", "#00FF00"},
* {"BLUE", "#0000FF"}});
* </pre>
*
* <p>This method returns <code>null</code> for a <code>null</code> input array.</p>
*
* @param array an array whose elements are either a {@link java.util.Map.Entry} or
* an Array containing at least two elements, may be <code>null</code>
* @return a <code>Map</code> that was created from the array
* @throws IllegalArgumentException if one element of this Array is
* itself an Array containing less then two elements
* @throws IllegalArgumentException if the array contains elements other
* than {@link java.util.Map.Entry} and an Array
*/
public static Map toMap(Object[] array) {
if (array == null) {
return null;
}
final Map map = new HashMap((int) (array.length * 1.5));
for (int i = 0; i < array.length; i++) {
Object object = array[i];
if (object instanceof Map.Entry) {
Map.Entry entry = (Map.Entry) object;
map.put(entry.getKey(), entry.getValue());
} else if (object instanceof Object[]) {
Object[] entry = (Object[]) object;
if (entry.length < 2) {
throw new IllegalArgumentException("Array element " + i + ", '"
+ object
+ "', has a length less than 2");
}
map.put(entry[0], entry[1]);
} else {
throw new IllegalArgumentException("Array element " + i + ", '"
+ object
+ "', is neither of type Map.Entry nor an Array");
}
}
return map;
}
}
