1. Introduction Methods

2. What is aMethod ?

Amethodis a kind of building block that solves a small problem

• A piece of code that has a name and can be called from the other code

Methods allow programmers to construct large programs from simple pieces

Methods are also known asfunctions ,procedures , andsubroutines

3. Why Use Methods?

More manageable programming

• Better organization of the program

• Easy to read programs

Avoid repeating code

Code reusability

• Using existing methods several times

4. Declaring andCreatingMethods 5. Declaring andCreatingMethods

Each method has aname

• It is used to call the method

• Describes its purpose

publicstatic voidprintLogo () { System.out.println("FunSoft Corp."); System.out.println ("www.funsoft.bg"); } 6. Declaring andCreatingMethods (2)

Methods declaredpubliccan be called by any other classes

• This will be discussed later in details

Methods declaredstaticcan be called by any other method (static or not)

• This will also be discussed later

The keywordvoidmeans that the method does not return any result

public s tatic void p rintLogo( ){ System.out.println("FunSoft Corp."); System.out.println ("www.funsoft.bg"); } 7. Declaring andCreatingMethods (3)

Each method has abody

• It contains the programming code

• Surrounded by{and}

publicstatic void printLogo() { System.out.println("FunSoft Corp."); System.out.println("www.funsoft.bg"); } 8. Using Parameters Defining and Using Method Parameters 9. MethodParameters

To pass information to a method, you can useparameters

• You can pass zero or several values

• You can pass values of different types

Use parameters to change the way the method works every time you call it

10. Defining and UsingMethod Parameters

Methods behavior depends on its parameters

Parameters can be of any type

• int ,double ,String , etc.

• arrays ( int[] ,double[] , etc.)

public static void printSign( int number ) { if ( number> 0) System.out.println("Positive"); else if ( number< 0) System.out.println("Negative"); else System.out.println("Zero"); } 11. Returning Values From Methods 12. Returning Values From Methods

A method canreturna value to its caller

Returned value:

• Can be assigned to a variable:

• Can be used in expressions:

• Can be passed to another method:

String message = input.nextLine(); // input.nextLine() returns a string float price =g etPrice ()* quantity * 1.20; System.out.println( input.nextLine() ) ; 13. Creating a Method That Returns a Value

Instead ofvoid , specify the type of data you want to return

Methods can return any type of data ( int ,String , array, etc.)

voidmethods do not return anything

Usereturnkeyword to return a result

public staticintmultiply(int number1, int number2) { returnnumber1 * number2; } 14. returnStatement

returnstatement:

• Terminatesmethods execution

• Returns the given expression to the caller

To terminatevoidmethod, simply writereturn;

You can use return several times in a method

15. Questions ? Methods Introduction