Copy pojo fields to another pojo's setters

Question

Let's say I have class A with public fields x and y. And let's say I have another pojo class B but that uses setters and getters, so it has setX() and setY().

I'd like to use some automatic way to copy from instance of A to B and back.

With default settings at least, Dozer's

   Mapper mapper = new DozerBeanMapper();
   B b = mapper.map(a, B.class);

does not copy the fields correctly.

So is there a simple configuration change that allows me to accomplish the above with Dozer, or another library that would do this for me?

Homeopathy

have you tried using JAXB, ObjectMapper? or you want to user dozer only? – Curculio

No I haven't. I'm happy to use any lib that offers "one line conversion" in the above situation. – Homeopathy

you would like to use jaxb, it does annotation based binding so i think it should work for you. checkout wiki.fasterxml.com/JacksonDocumentation and tutorial in the same page – Curculio

Answer 1

I'd suggest you use:

http://modelmapper.org/

Or take a look at this question:

Copy all values from fields in one class to another through reflection

I'd say that both API's (BeanUtils) and ModelMapper provide one-liners for copy pojos' values to another pojos. Take a look @ this:

http://modelmapper.org/getting-started/

Logy

Ok, ModelMapper does the job but there's one gotcha, you have to enable field mapping: mapper.getConfiguration().setFieldMatchingEnabled(true);. – Homeopathy

Answer 2

Not actually a one-liner but this approach doesn't require any libs.

I was testing it using these classes:

  private class A {
    public int x;
    public String y;

    @Override
    public String toString() {
      return "A [x=" + x + ", y=" + y + "]";
    }
  }

  private class B {
    private int x;
    private String y;

    public int getX() {
      return x;
    }

    public void setX(int x) {
      System.out.println("setX");
      this.x = x;
    }

    public String getY() {
      return y;
    }

    public void setY(String y) {
      System.out.println("setY");
      this.y = y;
    }

    @Override
    public String toString() {
      return "B [x=" + x + ", y=" + y + "]";
    }
  }

To get public field we can use reflection, as for setters it's better to use bean utils:

public static <X, Y> void copyPublicFields(X donor, Y recipient) throws Exception {
    for (Field field : donor.getClass().getFields()) {
      for (PropertyDescriptor descriptor : Introspector.getBeanInfo(recipient.getClass()).getPropertyDescriptors()) {
        if (field.getName().equals(descriptor.getName())) {
          descriptor.getWriteMethod().invoke(recipient, field.get(donor));
          break;
        }
      }
    }
  }

The test:

final A a = new A();
a.x = 5;
a.y = "10";
System.out.println(a);
final B b = new B();
copyPublicFields(a, b);
System.out.println(b);

And its output is:

A [x=5, y=10]
setX
setY
B [x=5, y=10]

Homunculus

Answer 3

For someone who is still looking for, You could try this using Gson

Gson gson = new Gson();
Type type = new TypeToken<YourPOJOClass>(){}.getType();
String data = gson.toJson(workingPOJO);
coppiedPOJO = gson.fromJson(data, type);

Ogilvy