Valid JavaBeans names for boolean getter methods

Question

I know most variable names will work with "is", such as isBlue(), but is "has" also a valid prefix, like hasProperty()?

Answer 1

According to the JavaBeans specification section 8.3.2:

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

public boolean is<PropertyName>();

This "isPropertyName" method may be provided instead of a "get<PropertyName>" method, or it may be provided in addition to a "get<PropertyName>" method. In either case, if the is<PropertyName> method is present for a boolean property then we will use the "is<PropertyName>" method to read the property value. An example boolean property might be:

public boolean isMarsupial(); public void setMarsupial(boolean m);

In other words, unless something has changed since then, has isn't a valid prefix I'm afraid :(

It's possible that some tools and libraries will recognise such properties anyway, but it's not a good idea to rely on it.

Answer 2

This is somewhat subjective, but yes, I would say "has" is a perfectly valid prefix for a Boolean property.

edit the question, as asked, did not mention the javabeans specification and so my answer did not address that aspect of the question. Hence the answer above.

Answer 3

Jon Skeet noted that according to the specification it is not valid. Also, canX, shouldX, and the likes are not valid. Which is rather unfortunate. Here is a way to check whether a given property has a valid getter:

BeanInfo info = Introspector.getBeanInfo(Item.class);
Item itm = new Item();
for (PropertyDescriptor pd : info.getPropertyDescriptors()) {
    System.out.println(pd.getName() + " : " + pd.getReadMethod());
}

The class Item should be a javabean with a foo property, and a getter. If the read method is null, it means there is no valid getter defined according to the javabeans spec.