A library class is a class that offers useful functionality that others might want to include in their program. For example, see the standard library of any language. The benefits are code reuse, faster development, predictible results, ect.
There are many reasons you might want to write some of your own.
You can often beat the execution speed of standard libraries, at the cost of extra development time and perhaps lessened reusability.
You might need functionality not found elsewhere.
You want to learn how to program, as opposed to just learning how to use java tools. Writing your own data structures, searching, sorting,networking, graphics, math libraries are great ways to become a better programmer and learning what is going on behind the scenes. [ June 08, 2006: Message edited by: Rusty Shackleford ]
"Computer science is no more about computers than astronomy is about telescopes" - Edsger Dijkstra
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