The Java object viewers in jGRASP provide interface-based and structural views of Java collections classes and arrays during debugging and workbench operations. Often these views are more useful than the traditional tree view showing the fields of each object. For example, an interface-based view shows ArrayList and LinkedList in an identical way, as a List. Structural views show the internal structure of HashMaps and LinkedLists, among others. In array and collection class viewers, one element or sub-element, such as an element of a LinkedList, or a key or value in a HashMap, may be selected and will be displayed in a "sub viewer".

Viewers for other Java API classes clearly show properties of the objects, such as the color represented by a java.awt.Color. There are also viewers for primitives and primitive wrapper classes, showing the computation of a floating point value from the bits, and showing integer types in hex, octal, decimal, and binary.

A public viewer API will be added to jGRASP in the future, so that users may create their own viewers.