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From "Vincenzo Vitale (JIRA)" <j...@apache.org>
Subject [jira] Created: (BEANUTILS-320) Implement equals, hashCode and toString replacement
Date Mon, 07 Jul 2008 23:32:31 GMT
Implement equals, hashCode and toString replacement
---------------------------------------------------

                 Key: BEANUTILS-320
                 URL: https://issues.apache.org/jira/browse/BEANUTILS-320
             Project: Commons BeanUtils
          Issue Type: New Feature
          Components: Bean / Property Utils
            Reporter: Vincenzo Vitale
            Priority: Minor


In my company (TomTom), I have internally developed a replacement of the equals, hashcode
and toString methods.

The base idea is to use the annotation @BusinessObject at the class level and @BusinessField
at field level. Then what developers normally do is to override the three methods delegating
to the tomtom.BeanUtils methods:

      @Override
        public boolean equals(Object obj) {
            return BeanUtils.equals(this, obj);
        }

        @Override
        public int hashCode() {
            return BeanUtils.hashCode(this);
        }

        @Override
        public String toString() {
            return BeanUtils.toString(this);
        }

And i.e. the method signature of equals is:

    /**
     * Compare two @BusinessObject beans comparing only the {@link BusinessField}
     * annotated fields.
     * 
     * @param firstBean First bean to compare.
     * @param secondBean Second bean to compare.
     * @return The equals result.
     * @throws IllegalArgumentException If one of the beans compared is not an
     *         instance of a {@link BusinessObject} annotated class.
     */
    public static boolean equals(Object firstBean, Object secondBean);

In the last versions of EqaulsBuilder now there is the new method reflectionEquals... but
there is no a way to specify what to include in the comparison. With our two annotations we
are able to let developers exactly define what need to be included in a Business comparison,
as i.e. normally required by persistence framework like hibernate. 

The current implementation can also handle more complex case, comparing correctly totally
different kind of objects.

For example if all my business logic cares only about the color, I can define:

@BusinessObject
public class Cat{

}

public class ColouredCat extends Cat{

@BusinessField
private String color;

getter/setter
}


@BusinessObject
public class SunSet{

@BusinessField
private String color="red";

getter/setter
}

and then compare any instance of ColouredCat with a Sunset instance, finding out that the
redColouredCat is (for my business logic) equal to a default instance of a Sunset. And also
more tricky cases are handled (different BusinessFields, no BusinessObject annotation and
so on).

We intensively use Hibernate and the utility demonstrated to work fine with CGLIB proxies



We always thought about the possibility to create a new Open Source project but the it was
decided than probably it would be better to add the feature to an already well know open source
project.
If you are interested I can send you more details. How can we (me more one other developer)
eventually became committers?


Thanks in advance,
Vicio.


P.s.: an utility method to automatically populate the BusinessFields of a BusinessObject is
also implemented.

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