hangen.java

When writing a bigger application the need to transform/map/copy one class into another arises. This is usually followed by the same tedious boilerplate code that copies values from a source class to a destination type.

I hate to write the same code over and over again and to test and maintain it is no easy chore either. And before I have thousands of methods like:

public Destination from(Source source){
    if(source == null){
        throw new NullPointerException("source can not be null");
    }
    Destination result = new Destination();

    result.setMember1(source.getMember1());
    result.setMember2(source.getMember2());
    result.setMember3(source.getMember3());
    //...
   
    return result;
}

An on top of that writing this code is tedious and mind numbing.

To provide a simple alternative I give you hangen.java.

After configuring the transformation rules a simple API call with copy all your data.

TransformationProvider transformer = new HangenReflectiveTransformationProvider();
// code where you get the source
Destination destination = transformer.from(source);
// destination is fully initialized and ready to use

This is the simplest sample. More complex scenarios are possible.