Techniques for checking in JAVA computing environments are disclosed. The techniques can be used by a JAVA virtual machine to efficiently perform type checking. A JAVA class hierarchy which represents the hierarchical relationship of parent classes of JAVA class can be implemented as an array of class references. The array of class references can be used to efficiently perform type checking in JAVA computing environments. As a result, the performance of JAVA virtual machines, especially those operating with limited resources, is significantly enhanced.