Getting a list of private properties of Java class / object

Question

How can I get a list of all the private properties of Java object used in getters and setters. I tried PropertyUtils and MethodUtils but no luck. Now I am trying to use getDeclaredFields() of the Class object which returns me a list of Field objects and then check if that is a private property is that a way to go? Or are there any better solutions to this.

Answer 1

This is quite old question post but i'll provide an answer here for the sake of new searches.

Using the approach provided by @highlycaffeinated here: https://stackoverflow.com/a/6796254/776860

You can easily come up with a desired solution with a couple of changes.

Retrieving a list of private field names only

public List<String> getMap(Object o) throws IllegalArgumentException, IllegalAccessException {
    List<String> result = new ArrayList<String>();
    Field[] declaredFields = o.getClass().getDeclaredFields();
    for (Field field : declaredFields) {
        if(!field.isAccessible()) {
            result.add(field.getName());
        }
    }
    return result;
}

Retrieving a Map of all field names and their values

public Map<String, Object> getMap(Object o) throws IllegalArgumentException, IllegalAccessException {
    Map<String, Object> result = new HashMap<String, Object>();
    Field[] declaredFields = o.getClass().getDeclaredFields();
    for (Field field : declaredFields) {
        field.setAccessible(true);
        result.put(field.getName(), field.get(o));
        } 
    }
    return result;
}

Exactly like @highlycaffeinated provided just with the additional line field.setAccessible(true); which enables you to introspect private fields too.

Answer 2

What you said, or maybe yourBean.getClass().getMethods() and then method.getName().startsWith("get") on each method returned.

May I ask why you need to do this for?

Answer 3

You could look for all the getters and setters and look to see if there is a matching field. However fields can start with _fieldName or m_fieldName You can only infer the getters/setters has something to do with the field.

Answer 4

I am doing this:

private Set<String> getModelProperties(Class<T> cls) {
    Set<String> properties = new HashSet<String>();
    for (Method method : cls.getDeclaredMethods()) {
        String methodName = method.getName();
        if (methodName.startsWith("set")) {
            properties.add(Character.toLowerCase(
              methodName.charAt(0)) + methodName.substring(3));
        }
    }

    return properties;
}