ObjectInspector helps us to look into the internal structure of a complex object. A (probably configured) ObjectInspector instance stands for a specific type and a specific way to store the data of that type in the memory. For native java Object, we can directly access the internal structure through member fields and methods. ObjectInspector is a way to delegate that functionality away from the Object, so that we have more control on the behavior of those actions. An efficient implementation of ObjectInspector should rely on factory, so that we can make sure the same ObjectInspector only has one instance. That also makes sure hashCode() and equals() methods of java.lang.Object directly works for ObjectInspector as well.
Nested Class Summary
static class ObjectInspector.Category
An ObjectInspector must inherit from one of the following interfaces if getCategory() returns: PRIMITIVE: PrimitiveObjectInspector LIST: ListObjectInspector MAP: MapObjectInspector STRUCT: StructObjectInspector.
Returns the name of the data type that is inspected by this ObjectInspector.