001/*-------------------------------------------------------------------------+
002|                                                                          |
003| Copyright 2005-2011 the ConQAT Project                                   |
004|                                                                          |
005| Licensed under the Apache License, Version 2.0 (the "License");          |
006| you may not use this file except in compliance with the License.         |
007| You may obtain a copy of the License at                                  |
008|                                                                          |
009|    http://www.apache.org/licenses/LICENSE-2.0                            |
010|                                                                          |
011| Unless required by applicable law or agreed to in writing, software      |
012| distributed under the License is distributed on an "AS IS" BASIS,        |
013| WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
014| See the License for the specific language governing permissions and      |
015| limitations under the License.                                           |
016+-------------------------------------------------------------------------*/
017package org.conqat.lib.commons.lang;
018
019import java.util.Comparator;
020import java.util.function.IntSupplier;
021
022/**
023 * Utility methods that help working with Java objects.
024 */
025public class ObjectUtils {
026
027        /**
028         * Compares the two given objects. First checks if they are reference-equal.
029         * If not, checks each for <code>null</code>. If both are non-null, calls
030         * <code>object1.compareTo(object2)</code>.
031         * 
032         * <code>null</code> values will be ordered before non-null values.
033         */
034        public static <T extends Comparable<T>> int compareNullSafe(T object1, T object2) {
035                return compareNullSafe(object1, object2, T::compareTo);
036        }
037
038        /**
039         * Compares the two given objects. First checks if they are reference-equal.
040         * If not, checks each for <code>null</code>. If both are non-null, passes
041         * them to the given comparator.
042         * 
043         * <code>null</code> values will be ordered before non-null values.
044         */
045        public static <T> int compareNullSafe(T object1, T object2, Comparator<T> comparator) {
046                if (object1 == object2) {
047                        return 0;
048                }
049                if (object1 == null) {
050                        return -1;
051                }
052                if (object2 == null) {
053                        return 1;
054                }
055                return comparator.compare(object1, object2);
056        }
057
058        /**
059         * Evaluates the given comparisons in order. If all of them evaluate to 0,
060         * returns 0, otherwise returns the first non-zero result.
061         */
062        public static int compareInOrder(IntSupplier... comparisonSuppliers) {
063                for (IntSupplier comparisonSupplier : comparisonSuppliers) {
064                        int comparisonResult = comparisonSupplier.getAsInt();
065                        if (comparisonResult != 0) {
066                                return comparisonResult;
067                        }
068                }
069                return 0;
070        }
071
072}