org.springmodules.validation.util.condition.range.NumberAwareComparableComparator.java Source code

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Here is the source code for org.springmodules.validation.util.condition.range.NumberAwareComparableComparator.java

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/*
 * Copyright 2004-2005 the original author or authors.
 *
 * 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 org.springmodules.validation.util.condition.range;

import java.math.BigDecimal;
import java.security.InvalidParameterException;

import org.springframework.util.comparator.ComparableComparator;

/**
 * A comparator that compares {@link Comparable} instances but treats comparison
 * of {@link Number} instances in a special manner. In order to support
 * comparison of numbers regardless of their type, this comparator transform the
 * numbers to {@link BigDecimal} and then does the comparison.
 * 
 * @author Uri Boness
 */
public class NumberAwareComparableComparator extends ComparableComparator {

    /**
     * Compares the two given objects. Expects both of them to be
     * {@link Comparable} instances.
     * 
     * @see ComparableComparator#compare(Object, Object)
     */
    public int compare(Object o1, Object o2) {
        if (Number.class.isInstance(o1) && Number.class.isInstance(o2)) {
            return compareNumbers((Number) o1, (Number) o2);
        }

        throw new InvalidParameterException("Object must be of type number");
    }

    /**
     * Compares the two given numbers. These numbers are compared regardless of
     * their type.
     * 
     * @param n1
     *            The first number.
     * @param n2
     *            The second number.
     * @return possitive number if <code>n1 &gt; n2</code>, negative number if
     *         <code>n1 &lt; n2</code>, or 0 (Zero) if <code>n1 == n2</code>.
     */
    protected int compareNumbers(Number n1, Number n2) {
        BigDecimal bd1 = new BigDecimal(n1.toString());
        BigDecimal bd2 = new BigDecimal(n2.toString());
        return bd1.compareTo(bd2);
    }

}