001    /*
002     * Copyright 2002-2005 the original author or authors.
003     *
004     * Licensed under the Apache License, Version 2.0 (the "License");
005     * you may not use this file except in compliance with the License.
006     * You may obtain a copy of the License at
007     *
008     *      http://www.apache.org/licenses/LICENSE-2.0
009     *
010     * Unless required by applicable law or agreed to in writing, software
011     * distributed under the License is distributed on an "AS IS" BASIS,
012     * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
013     * See the License for the specific language governing permissions and
014     * limitations under the License.
015     */
016    package org.springframework.binding.validation;
017    
018    import java.util.Comparator;
019    
020    import org.springframework.util.comparator.NullSafeComparator;
021    
022    /**
023     * Comparator that compares ValidationMessages. Comparison is done by timestamp
024     * (desc) then property name then severity then message.
025     *
026     * @author Oliver Hutchison
027     */
028    public class ValidationMessageComparator implements Comparator {
029    
030            /**
031             * A shared default instance of this comparator.
032             */
033            public static Comparator INSTANCE = new NullSafeComparator(new ValidationMessageComparator(), true);
034    
035            protected ValidationMessageComparator() {
036            }
037    
038            public int compare(Object o1, Object o2) {
039                    ValidationMessage m1 = (ValidationMessage) o1;
040                    ValidationMessage m2 = (ValidationMessage) o2;
041                    int c;
042                    if (m1.getTimestamp() == m2.getTimestamp()) {
043                            c = NullSafeComparator.NULLS_HIGH.compare(m1.getProperty(), m2.getProperty());
044                            if (c == 0) {
045                                    c = m1.getSeverity().compareTo(m2.getSeverity());
046                                    if (c == 0) {
047                                            c = m1.getMessage().compareTo(m2.getMessage());
048                                    }
049                            }
050                    }
051                    else {
052                            c = (m1.getTimestamp() > m2.getTimestamp()) ? -1 : 1;
053                    }
054                    return c;
055            }
056    
057    }