Question

I am using introspection to retrieve a beans get methods and i’d like to be able to determine if the result is an Array or a Primitive, but I always get a false response. Even when I know that the type is an ArrayList. On that same note, will isArray() work for all types of Arrays such as primitive Array, ArrayList etc?

Class<?> className = bean1.getClass();
ArrayList<ComparatorValue> updateIndexes = new ArrayList<ComparatorValue>();            
BeanInfo beanInfo = Introspector.getBeanInfo(className);
PropertyDescriptor classProperties[] = beanInfo.getPropertyDescriptors();


for(int i=0; i<classProperties.length; i++) {
    Method getter = classProperties[i].getReadMethod();
    System.out.println(getter.invoke(bean1).getClass().isArray()); //Always false.
    System.out.println(getter.invoke(bean1).getClass().isPrimitive()); //Always false.
}

Answer 1

When you invoke the method, a primitive return value will get boxed into its wrapper class.

getter.invoke(bean1).getClass().isPrimitive()

Since you are calling getClass on the wrapped return value, isPrimitve will return false. You can retrieve the actual return type by calling getter.getReturnType().