How to get Java reflect to spot fields in the super class? not just the actual class

Question

I've recently changed my schema a bit so my classes inherit from a super class, problem is my comparison method which generates an audit log, using Java reflect, is now only looping through the fields of the child class, not the superclass, is there a way to get all the FIELDS? or do I need to cast it into the super class.....?

Heres my method below:

public static <T> String GenerateChangeLogForEntity(T old, T updated) {
        String text = "";
        try {
            Field[] fields = old.getClass().getDeclaredFields();
            if(fields != null) {
                BaseController.getLogger().info("Z1 num fields:"+fields.length);
                for (Field field : fields) {
                    if(field.isAnnotationPresent(Column.class)) {
                        String fieldName = field.getName();
                        BaseController.getLogger().info(field.getName());
                        if(field.isAnnotationPresent(Variation.class)) {
                            Variation v = field.getAnnotation(Variation.class);
                            fieldName = v.friendlyName();
                        }
                        field.setAccessible(true);
                        if(field.get(old) != null && field.get(updated) != null) {
                            if(!(field.get(old)).equals(field.get(updated))) {
                                text += "<p><span class=\"field-name\">"+fieldName+"</span> changed from: <strong>"+GetFriendlyFieldValueForChangeLog(field.get(old))+"</strong>  to: <strong>"+GetFriendlyFieldValueForChangeLog(field.get(updated)) + "</strong></p>";
                            }
                        }
                        if(field.get(old) == null && field.get(updated) != null) {
                            text += "<p><span class=\"field-name\">"+fieldName+"</span> changed from: <strong>empty</strong> to: <strong>"+GetFriendlyFieldValueForChangeLog(field.get(updated)) + "</strong></p>";
                        }
                        if(field.get(old) != null && field.get(updated) == null) {
                            text += "<p><span class=\"field-name\">"+fieldName+"</span> changed from: <strong>"+GetFriendlyFieldValueForChangeLog(field.get(updated))+"</strong> to <strong>empty</strong>" + "</p>";
                        }
                        field.setAccessible(false);
                    }
                }
            }
        } catch(IllegalAccessException e) {}
        return text;
    }

N.B: You probably shouldn't set `field.setAccessible(false)` to prevent race conditions in multi-threaded environments... — Lukas Eder, May 14 '12 at 09:45
your means is: `instance.getClass().getSuperCLass().getDeclaredFields()`? — Sam, May 14 '12 at 09:55
Thanks MJM, thanks everyone, yip that did it easy as pie! :) — williamsandonz, May 14 '12 at 10:08

score 43 · Accepted Answer · answered May 14 '12 at 09:45

43

You can use this.getClass().getSuperClass() until this getSuperClass() method returns null to get the parent fields.

So, the best would be that you factorize your code. Implement one method that takes a list of Field as parameter and do your logical part within it, and a main method that search for fields through a while(superClass != null) loop.

answered May 14 '12 at 09:45

sp00m

47,968
31
142
252

2

watch for the getFilds() method, in my case it does not work for the superclass. I was only successful with the getDeclaredFilds() – Gonçalo Mar 13 '14 at 16:53

score 18 · Answer 2 · edited Dec 07 '16 at 00:08

Though it's late, I'm adding my suggestion since it's a nice solution.

Spring framework provide a nice Util class org.springframework.util.ReflectionUtils this class has several methods which we can use. To get a Field instance of an attribute from objectClass and superClasses I used ReflectionUtils.findField(clazz, fieldName);

Good thing with util is it doesn't throw an exception. Instead it returns null for invalid ones, so you can handle it gracefully.

score 9 · Answer 3 · answered Oct 03 '18 at 07:27

9

Apache Commons Lang provides a method FieldUtils.getAllFields() which is an implementation of @sp00m's algorithm.

answered Oct 03 '18 at 07:27

Václav Kužel

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16

How to get Java reflect to spot fields in the super class? not just the actual class

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