Question

I have a POJO, and a (currently not-yet-built) class that will return Lists of it. I’d like to automatically generate the code necessary for the POJO to be accessed as a Map. Is this a good idea, is it possible to do automatically, and do I need to do this manually for every POJO I want to treat this way?

Thanks,
Andy

Answer 1

You can use Commons BeanUtils BeanMap for this.

Map map = new BeanMap(someBean);

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Update: since that’s not an option due to some apparent library dependency problems in Android, here’s a basic kickoff example how you could do it with little help of Reflection API:

public static Map<String, Object> mapProperties(Object bean) throws Exception {
    Map<String, Object> properties = new HashMap<>();
    for (Method method : bean.getClass().getDeclaredMethods()) {
        if (Modifier.isPublic(method.getModifiers())
            && method.getParameterTypes().length == 0
            && method.getReturnType() != void.class
            && method.getName().matches("^(get|is).+")
        ) {
            String name = method.getName().replaceAll("^(get|is)", "");
            name = Character.toLowerCase(name.charAt(0)) + (name.length() > 1 ? name.substring(1) : "");
            Object value = method.invoke(bean);
            properties.put(name, value);
        }
    }
    return properties;
}

If java.beans API were available, then you could just do:

public static Map<String, Object> mapProperties(Object bean) throws Exception {
    Map<String, Object> properties = new HashMap<>();
    for (PropertyDescriptor property : Introspector.getBeanInfo(bean.getClass()).getPropertyDescriptors()) {
        String name = property.getName();
        Object value = property.getReadMethod().invoke(bean);
        properties.put(name, value);
    }
    return properties;
}