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Posted to issues@commons.apache.org by "Paul Benedict (JIRA)" <ji...@apache.org> on 2010/01/11 05:23:54 UTC
[jira] Updated: (LANG-403) HashcodeBuilder is broken for
Annotations
[ https://issues.apache.org/jira/browse/LANG-403?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]
Paul Benedict updated LANG-403:
-------------------------------
Fix Version/s: (was: 3.0)
3.x
Without a patch, moving this to post 3.0 release.
> HashcodeBuilder is broken for Annotations
> -----------------------------------------
>
> Key: LANG-403
> URL: https://issues.apache.org/jira/browse/LANG-403
> Project: Commons Lang
> Issue Type: Bug
> Components: lang.builder.*
> Affects Versions: 2.3
> Reporter: Jay Liang
> Fix For: 3.x
>
>
> HashCodeBuilder does not produce a correct hashCode that conforms to java language specs. Running the following code snippets, i get
> @Simple$CustomAnnotation(name=blah, type=class java.lang.String) hashCode= 895255138
> Simple$CustomAnnotationImpl@665753[_name=blah,_type=class java.lang.String] hashCode= 122852694
> hashCode should be 895255138
> The hashCode should computed according to http://java.sun.com/j2se/1.5.0/docs/api/java/lang/annotation/Annotation.html#hashCode() for annotations.
> {code:java}
> public class Simple{
> @Retention(RetentionPolicy.RUNTIME)
> @Target({FIELD, METHOD, PARAMETER})
> private @interface CustomAnnotation{
> public String name();
> public Class<?> type();
> }
> private static class CustomAnnotationImpl implements CustomAnnotation{
> final String _name;
> final Class<?> _type;
> public CustomAnnotationImpl(String name, Class<?> type) {
> _name = name;
> _type = type;
> }
> public String name() {
> return _name;
> }
> public Class<?> type() {
> return _type;
> }
> public Class<? extends Annotation> annotationType() {
> return CustomAnnotation.class;
> }
> @Override
> public int hashCode() {
> return HashCodeBuilder.reflectionHashCode(this);
> }
> /**
> * This conform to specs defined at http://java.sun.com/j2se/1.5.0/docs/api/java/lang/annotation/Annotation.html#hashCode
> * @return good annotation hashCode
> */
> public int goodHashCode() {
> return (127 * "name".hashCode() ^ _name.hashCode()) + (127 *"type".hashCode() ^ _type.hashCode());
> }
>
> @Override
> public String toString() {
> return ToStringBuilder.reflectionToString(this);
> }
> }
> private static class Test{
> @CustomAnnotation(name="blah", type=String.class)
> String _blah;
> @Override
> public String toString() {
> return ToStringBuilder.reflectionToString(this);
> }
> }
>
> public static void main(String[] args) throws Exception{
> for(Field f : Test.class.getDeclaredFields()){
> for(Annotation a : f.getAnnotations()){
> System.out.println(a + " hashCode= " + a.hashCode());
> CustomAnnotationImpl c = new Simple.CustomAnnotationImpl("blah", String.class);
> System.out.println(c + " hashCode= " + c.hashCode());
> System.out.println("hashCode should be "+ c.goodHashCode());
> }
> }
> }
> }
> {code}
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