Convert String to Enum using Apache BeanUtils

Question

I've implemented a converter for Apache BeanUtils library for converting String to an enum constant:

class EnumConverter implements Converter {    
    @Override
    public <T> T convert(Class<T> tClass, Object o) {
        String enumValName = (String) o;
        Enum[] enumConstants = (Enum[]) tClass.getEnumConstants();

        for (Enum enumConstant : enumConstants) {
            if (enumConstant.name().equals(enumValName)) {
                return (T) enumConstant;
            }
        }

        throw new ConversionException(String.format("Failed to convert %s value to %s class", enumValName, tClass.toString()));
    }
}

I use it in the following way:

// Register my converter    
ConvertUtils.register(new EnumConverter(), Enum.class);
Map<String, String> propMap = new HashMap<String, String>();
// fill property map    
BeanUtils.populate(myBean, propMap);

Unfortunatelly a setter in myBean instance except ConcreteEnumClass enum, instead of java.lang.Enum, that is why I receive the following exception during BeanUtils.populate method call:

org.apache.commons.beanutils.ConversionException: Default conversion to ConcreteEnumClass failed.
    at org.apache.commons.beanutils.converters.AbstractConverter.handleMissing(AbstractConverter.java:314)
    at org.apache.commons.beanutils.converters.AbstractConverter.handleError(AbstractConverter.java:269)
    at org.apache.commons.beanutils.converters.AbstractConverter.convert(AbstractConverter.java:177)
    at org.apache.commons.beanutils.converters.ConverterFacade.convert(ConverterFacade.java:61)
    at org.apache.commons.beanutils.ConvertUtilsBean.convert(ConvertUtilsBean.java:491)
    at org.apache.commons.beanutils.BeanUtilsBean.setProperty(BeanUtilsBean.java:1000)
    at org.apache.commons.beanutils.BeanUtilsBean.populate(BeanUtilsBean.java:821)
    at org.apache.commons.beanutils.BeanUtils.populate(BeanUtils.java:431)

If I register EnumConverter in the following way:

ConvertUtils.register(new EnumConverter(), ConcreteEnumClass.class);

Everything woks perfectly.

Since I would like to use my EnumConverter in general case, I would prefer it be used to convert String to any enum class.

Is it possible? How should I do it?

Answer 1

As of the current BeanUtils v1.9.2 I don't believe there is any way to do this when using the static singleton BeanUtils and ConvertUtils classes.

You could create an instance of BeanUtilsBean, passing a custom ConvertUtilsBean instance that has special handling for Enum targets.

An example is shown here (not my example, credit to its author "jeremychone"): http://www.bitsandpix.com/entry/java-beanutils-enum-support-generic-enum-converter/

Jeremy's simple implementation is as follows:

BeanUtilsBean beanUtilsBean = new BeanUtilsBean(new ConvertUtilsBean() {
    @Override
    public Object convert(String value, Class clazz) {
        if (clazz.isEnum()) {
            return Enum.valueOf(clazz, value);
        } else {
            return super.convert(value, clazz);
        }
    }
});