Question

I am trying to compare the field values of two different objects in a generic way. I have a function (seen below) that takes in two Objects and then gets the fields and then compares the fields in a loop and adds the fields to a list if they are not the same – is this the proper way to do this?

public void compareFields(Object qa, Object qa4) throws FieldsNotEqualException
{

  Field[] qaFields = qa.getClass().getFields();
  Field[] qa4Fields = qa4.getClass().getFields();

  for(Field f:qaFields) 
  { 

    for(Field f4:qa4Fields)
    {
       if(f4.equals(f))
       {
           found = true;
           break;
       }
       else
       {
           continue;
       }
    }
  }

 if(!found)
 {
    report.add(/*some_formatted_string*/) //some global list 
    throw new FieldsNotEqualException();
 }
}

I was googling and I saw that C# had like a PropertyInfo Class – does Java have anything like that?
ALSO, is there a way to do like f.getFieldValue() -I know there is no method like this but maybe there is another way???

Answer 1

You might check out org.apache.commons.lang.builder.EqualsBuilder which will save you a lot of this hassle if you’re wanting to do a field by field comparison.

org.apache.commons.lang.builder.EqualsBuilder.reflectionEquals(Object, Object)

If you’re wanting to compare fields yourself, check out java.lang.Class.getDeclaredFields() which will give you all the fields including non-public fields.

To compare the value of the fields use f.get(qa).equals(f.get(qa4)) Currently, you are actually comparing the field instances and not the values.