You have two instances of a bean, and you need to copy the properties of one bean to another instance of the same class.
Use PropertyUtils.copyProperties()
to copy the properties from one bean to
another. The first parameter is the destination bean, and the second
parameter is the bean to copy properties from:
import org.apache.commons.beanutils.PropertyUtils; Book book = new Book( ); book.setName( "Prelude to Foundation" ); book.setAuthorName( "Asimov" ); Book destinationBook = new Book( ); PropertyUtils.copyProperties( destinationBook, book );
After executing this code, destinationBook.getName()
should return “Prelude to
Foundation,” and
destinationBook.getAuthorName( )
should return
“Asimov”; the
name
and authorName
properties
of book
were both copied to
destinationBook
.
PropertyUtils.copyProperties( )
retrieves the
values of all properties from a source instance of a bean, assigning
the retrieved values to a matching property on a destination
instance. If the Book
bean in the previous example
had an author
property of type
Author
, copyProperties( )
would
have assigned the same reference object to the
destinationBook
. In other words,
copyProperties( )
does not
clone the values of the bean properties. The following example
demonstrates this explicitly:
Author author = new Author( ); author.setName( "Zinsser" ); Book book = new Book( ); book.setName( "On Writing Well" ); book.setAuthor( author ); Book destinationBook = new Book( ); PropertyUtils.copyProperties( destinationBook, book ); // At this point book and destinationBook have the same author object if( book.getAuthor( ) == destinationBook.getAuthor( ) ) { system.out.println( "Author objects identical" ); }
The author
properties of these two objects are now
identical references to the same instance of the
Author
class. copyProperties( )
does not clone the values of bean properties.
copyProperties( )
can also copy the contents of a
Map
to a bean if the keys of a
Map
correspond to names of simple bean properties
on the destination bean:
Map mapProps = new HashMap( ); mapProps.put( "name", "The Art of Computer Programming" ); mapProps.put( "author", "Knuth" ); Book destinationBook = new Book( ); PropertyUtils.copyProperties( destinationBook, mapProps );
If you need to clone a bean, take a look at Recipe 3.12
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