In contrast, a data structure is a concrete implementation of one or more ADTs, similar to how Java classes implement interfaces. Examples of ADTs include Employee, Vehicle, Array, and List.

Ragged arrays are useful data structures because of their memory-saving capability. For example, consider a spreadsheet with the potential for 100,000 rows by 20,000 columns.

The Java Platform provides the most commonly used data structures in the form of the Collections Framework, ... Listing A shows a simple example that illustrates some of the concepts we've been ...