## Hierarchy Views Show Multi-Level Relationships

Hierarchy views show the relationships between entities. Here are examples of the types of hierarchy views that Understand for Java offers.

- Invocation - Shows the entire chain of invocations emanating from this function. Each line between entities is read as “entity invokes entity”. In this example, CharIndexedReader.move invokes CharIndexedReader.nextwhich invokes br.reset (and others).
- Call By - Shows who calls a function, and who calls each parent. Each line connecting an entity is read as “entity is called by entity”. In this example, Getopt.getOptind is called by GetoptDemo.main. Note that this view is read from the bottom up or right to left.
- Extends - Shows which classes extend other classes. In this example, the regexp.UncheckedRE class extends the regexp.RE class, which extends the regexp.REToken class.
- Extended By - Shows which classes are extended by other classes. An arrow is read as “class is extended by class.” In this example, the regexp.REToken class is extended by a number of classes, including the regexp.RE class, which in turn is extended by the regexp.UncheckedRE class.

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