How to copy properties from one Java bean to another ?

Question

I have a simple Java POJO that I would copy properties to another instance of same POJO class.

I know I can do that with BeanUtils.copyProperties() but I would like to avoid use of a third-party library.

So, how to do that simply, the proper and safer way ?

By the way, I'm using Java 6.

Answer 1

I guess if you look at the source code of BeanUtils, it will show you how to do this without actually using BeanUtils.

If you simply want to create a copy of a POJO (not quite the same thing as copying the properties from one POJO to another), you could change the source bean to implement the clone() method and the Cloneable interface.

Answer 2

Have a look at the JavaBeans API, in particular the Introspector class. You can use the BeanInfo metadata to get and set properties. It is a good idea to read up on the JavaBeans specification if you haven't already. It also helps to have a passing familiarity with the reflection API.

Answer 3

There is no simple way to do it. Introspector and the Java beans libraries are monolithic - BeanUtils is a simple wrapper around this and works well. Not having libraries just to not have libraries is a bad idea in general - there's a reason it's commons to begin with - common functionality that should exist with Java, but doesn't.