net.sf.infrared.web.util.BeanComparator.java Source code

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Here is the source code for net.sf.infrared.web.util.BeanComparator.java

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/* 
 * Copyright 2005 Tavant Technologies and Contributors
 * 
 * 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.                                                                                               
 * 
 *
 *
 * Original Author:  kamal.govindraj (Tavant Technologies)
 * Contributor(s):   -;
 *
 */
package net.sf.infrared.web.util;

import java.lang.reflect.InvocationTargetException;
import java.util.Comparator;

import org.apache.commons.beanutils.MethodUtils;

/**
 * A simple comparator implementation that enables comparing two
 * bean instances based on a specified property.
 */
public class BeanComparator implements Comparator {
    String methodName = null;
    boolean ascending = true;

    public BeanComparator(String methodName, boolean ascending) {
        this.methodName = methodName;
        this.ascending = ascending;
    }

    public int compare(Object o1, Object o2) {
        Object fieldOne = null;
        Object fieldTwo = null;
        try {
            fieldOne = MethodUtils.invokeExactMethod(o1, methodName, null);
            fieldTwo = MethodUtils.invokeExactMethod(o2, methodName, null);
        } catch (NoSuchMethodException e) {
            throw new RuntimeException(e);
        } catch (IllegalAccessException e) {
            throw new RuntimeException(e);
        } catch (IllegalArgumentException e) {
            throw new RuntimeException(e);
        } catch (InvocationTargetException e) {
            throw new RuntimeException(e);
        }

        if (fieldOne != null && fieldTwo != null && fieldOne.getClass().equals(fieldTwo.getClass())
                && fieldOne instanceof Comparable && fieldTwo instanceof Comparable) {
            int retValue = ((Comparable) fieldOne).compareTo(fieldTwo);
            return (ascending ? retValue : (retValue * -1));
        } else {
            throw new IllegalArgumentException(
                    "Error comparing object " + o1.toString() + " with " + o2.toString());
        }
    }

    public void setAscending(boolean ascending) {
        this.ascending = ascending;
    }

}