Java Beans, BeanUtils, and the Boolean wrapper class

Question

I'm using BeanUtils to manipulate Java objects created via JAXB, and I've run into an interesting issue. Sometimes, JAXB will create a Java object like this:

public class Bean {
    protected Boolean happy;

    public Boolean isHappy() {
        return happy;
    }

    public void setHappy(Boolean happy) {
        this.happy = happy;
    }
}

The following code works just fine:

Bean bean = new Bean();
BeanUtils.setProperty(bean, "happy", true);

However, attempting to get the happy property like so:

Bean bean = new Bean();
BeanUtils.getProperty(bean, "happy");

Results in this exception:

Exception in thread "main" java.lang.NoSuchMethodException: Property 'happy' has no getter method in class 'class Bean'

Changing everything to a primitive boolean allows both the set and get call to work. I don't have this option, however, since these are generated classes. I assume this happens because the Java Bean libraries only consider an is<name> method to represent a property if the return type is a primitive boolean, and not the wrapper type Boolean. Does anyone have a suggestion as to how to access properties like these through BeanUtils? Is there some kind of workaround I can use?

Nettienetting

Where does the BeanUtils class come from? I checked with org.apache.commons.beanutils.BeanUtils (1.8.3) and it works fine. Please note that typically is prefix is used for boolean, while for Boolean: get. – Autoionization

I'm using the same BeanUtils. You were able to do a getProperty() with an is method that returns the Boolean wrapper class? – Nettienetting

Your assumption about is<name> is correct. isXXX only applys to type boolean return type. For Boolean return type, getXXX is the correct method name. – Carr

you're right, getProperty() does not work with Boolean is. In fact, IntelliJ generates getters with get for Boolean and is for boolean - I guess Eclipse does the same. – Autoionization

Answer 1

Finally I've found legal confirmation:

8.3.2 Boolean properties

In addition, for boolean properties, we allow a getter method to match the pattern:

public boolean is<PropertyName>();

From JavaBeans specification. Are you sure you haven't came across JAXB-131 bug?

Autoionization

Yep, looks like I was running into that bug. I upgraded my JAXB version to 2.1.13 and added the "-enableIntrospection" flag. That changed all the Boolean wrapper is methods to gets. Thanks! – Nettienetting

Answer 2

Workaround to handle Boolean isFooBar() case with BeanUtils

1. Create new BeanIntrospector

---

private static class BooleanIntrospector implements BeanIntrospector{
    @Override
    public void introspect(IntrospectionContext icontext) throws IntrospectionException {
        for (Method m : icontext.getTargetClass().getMethods()) {
            if (m.getName().startsWith("is") && Boolean.class.equals(m.getReturnType())) {
                String propertyName = getPropertyName(m);
                PropertyDescriptor pd = icontext.getPropertyDescriptor(propertyName);

                if (pd == null)
                    icontext.addPropertyDescriptor(new PropertyDescriptor(propertyName, m, getWriteMethod(icontext.getTargetClass(), propertyName)));
                else if (pd.getReadMethod() == null)
                    pd.setReadMethod(m);

            }
        }
    }

    private String getPropertyName(Method m){
        return WordUtils.uncapitalize(m.getName().substring(2, m.getName().length()));
    }

    private Method getWriteMethod(Class<?> clazz, String propertyName){
        try {
            return clazz.getMethod("get" + WordUtils.capitalize(propertyName));
        } catch (NoSuchMethodException e) {
            return null;
        }
    }
}

---

1. Register BooleanIntrospector:

   BeanUtilsBean.getInstance().getPropertyUtils().addBeanIntrospector(new BooleanIntrospector());

Holystone

Good stuff! I think there are 2 changes needed though: in getWriteMethod, it should be "set" - and also, I was getting MethodNotFoundExceptions until I changed to the overloaded method that receives a parameter type: return clazz.getMethod("set" + WordUtils.capitalize(propertyName), Boolean.class); – Cheekbone

Answer 3

you can just create second getter with SET - sufix as workaround :)

Corposant