source: trunk/java-utils/src/main/java/de/ugoe/cs/util/ArrayTools.java @ 2231

//   Copyright 2012 Georg-August-Universität Göttingen, Germany
//
//   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 de.ugoe.cs.util;

/**
 * <p>
 * Helper class that provides methods to simplify working with arrays.
 * </p>
 * 
 * @author Steffen Herbold
 * @version 1.0
 */
final public class ArrayTools {

        /**
         * <p>
         * Private constructor to prevent initializing of the class.
         * </p>
         */
        private ArrayTools() {

        }

        /**
         * <p>
         * Finds the first occurrence of an object inside an array.
         * </p>
         * <p>
         * In case {@code other==null}, the first occurrence of a {@code null} value
         * in the array is returned.
         * </p>
         * 
         * @param array
         *            the array
         * @param other
         *            the object
         * @return index of the object if found, -1 otherwise
         */
        public static int findIndex(Object[] array, Object other) {
                int retVal = -1;
                for (int i = 0; i < array.length && retVal == -1; i++) {
                        if (other != null) {
                                if (array[i] != null && array[i].equals(other)) {
                                        retVal = i;
                                }
                        } else {
                                if (array[i] == null) {
                                        retVal = i;
                                }
                        }
                }
                return retVal;
        }

        /**
         * <p>
         * Finds the highest element in an array. If multiple elements have the
         * maximum value, the index of the first one is returned; null-values are
         * ignored. In case the parameter array is null, has length 0 or contains
         * only null-values, -1 is returned.
         * </p>
         * 
         * @param <T>
         * @param array
         *            the array
         * @return index of the element with the highest value, -1 in case of an
         *         invalid parameter
         */
        @SuppressWarnings("unchecked")
        public static <T> int findMax(Comparable<T>[] array) {
                int maxIndex = -1;
                T maxElement = null;
                if (array != null) {
                        for (int i = 0; i < array.length; i++) {
                                if (array[i] != null) {
                                        if (maxElement == null
                                                        || array[i].compareTo(maxElement) > 0) {
                                                maxElement = (T) array[i];
                                                maxIndex = i;
                                        }
                                }
                        }
                }
                return maxIndex;
        }
        
        /**
         * <p>
         * Finds the highest element in an array. If multiple elements have the
         * maximum value, the index of the first one is returned; null-values are
         * ignored. In case the parameter array is null, has length 0 or contains
         * only null-values, -1 is returned.
         * </p>
         * 
         * @param array
         *            the array
         * @return index of the element with the highest value, -1 in case of an
         *         invalid parameter
         */
        public static int findMax(double[] array) {
                int maxIndex = -1;
                double maxElement = -Double.MAX_VALUE;
                if (array != null) {
                        for (int i = 0; i < array.length; i++) {
                                if (array[i] > maxElement) {
                                        maxElement = array[i];
                                        maxIndex = i;
                                }
                        }
                }
                return maxIndex;
        }

        /**
         * <p>
         * Finds the lowest element in an array. If multiple elements have the
         * minimal value, the index of the first one is returned; null-values are
         * ignored. In case the parameter array is null, has length 0 or contains
         * only null-values, -1 is returned.
         * </p>
         * 
         * @param <T>
         * @param array
         *            the array
         * @return index of the element with the lowest value, -1 in case of an
         *         invalid parameter
         */
        @SuppressWarnings("unchecked")
        public static <T> int findMin(Comparable<T>[] array) {
                int maxIndex = -1;
                T maxElement = null;
                if (array != null) {
                        for (int i = 0; i < array.length; i++) {
                                if (array[i] != null) {
                                        if (maxElement == null
                                                        || array[i].compareTo(maxElement) < 0) {
                                                maxElement = (T) array[i];
                                                maxIndex = i;
                                        }
                                }
                        }
                }
                return maxIndex;
        }
}