U3: User Defined Methods

Create program, run it, alter code until desired result

• Completing program in trial-and-error method closer and closer to solution • Ex: Writing first part of program, perfecting, then continuing

Breaks task into smaller parts

• Building large programs through combining separate chunks of code • Possible by creating main program, then creating separate subroutines for program

• public static void [method] (data) • AKA: Subroutine definition

Code of the method

Ex: public and static

• Access specifier stating where subroutine can be called from • Private: Just within selected part of program • Public: Other parts

• Begin with lowercase • Camel notation • Descriptive name • No reserved words

Ensures subroutine can exist on own and not as part of object

• Different, simpler name from ones in main program • Only exist within subroutine • Wiped from memory when subroutine done executing

• Program control transferred to subroutine when latter is called • Transferred to main program when subroutine done executing

Performs task but doesn’t return data to main program; returns void

Write arguments in brackets in same order as parameters

• Performs task and returns data to main program • Return type specified and return statement concludes subroutine

Int, Double, String, Void, etc

Used when no data returned to main program

return (variable);

• Output to screen on the same line as the method call OR • Use variable in main program to store data

• Declared within main class • Include both procedures and functions • Can’t return +1 piece of data

Done while declaring subroutine

Done while calling subroutine

Possible for same data type in the main program, not in subroutines

Comments explaining subroutine function, inputs and outputs, parameters passed, data returned (if any).