1. Methods
Chapter 6

2. Program Modules in Java
What we call "functions" in C++ are called "________________" in Java
Purpose
Reuse code
______________________ the program
This can be done by putting the code in a method
Various objects in a program can invoke the same method

3. Program Modules _______________ and ______________ technique
Construct a large program from smaller pieces (or modules)
Can be accomplished using methods
______________ methods can be called without the need for an object of the class

4. static Methods static method (or class method)
Applies to the class as a whole instead of a specific object of the class
Call a static method by using the method call: _____________.methodName( arguments )
All methods of the __________ class are static
example: Math.sqrt( )

5. static Methods Method main
main is declared static so it can be invoked _____________________________ of the class containing main
Any class can contain a main method
The JVM invokes the main method belonging to the class specified by the first command-line argument to the java command

6. Predefined Methods The Math class These methods are called by
The _____________ of the class
The dot . operator
The name of the ______________
Example: double y = Math.cos(x);

7. Constants Constants static fields (or class variables)
Keyword ___________________
Cannot be changed after initialization
static fields (or class variables)
Are fields where one copy of the variable is __________________ among all objects of the class
Math.PI and Math.E are final static fields of the Math class

8. Method Declaration Syntax
modifiers returnType methodName (parameterDeclaration) {
statements }
___________ : describers (public, private, etc.)
returnType : type of value returned by method, or ____________ if it does not return a value
methodName : identifier that names the method
parameterDeclaration : list of parameters, separated by _______________________
statements : define the behavior of the method

9. Method Declaration
View declaration of methods in a class for finding maximums, Fig. 6.3
Note method for input, call of method ______________
Note method for actual determining of maximum
View test program, Fig 6.4
Note declaration of instance of new class
Note call of class methods

10. Alternative Method Declaration
View alternative solution
Declare methods in the __________________
Have them follow method main()
Although they can be ____________ in the class
Note they must be static

11. Declaring and Using Methods
Three ways to call a method:
Use a method name by itself to call ____________ of the same class
Use a containing a reference to an object, followed by a dot (.) and the method name to call a method of the referenced object
Use the class name and a dot (.) to call a _______ method of a class
Note: static methods cannot call non-static methods of the same class directly

12. Declaring and Using Methods
Three ways to return control to the calling statement:
If method does not return a result:
Program flow reaches the _________________ right brace or …
Program executes the statement _____________;
If method does return a result:
Program executes the statement __________ expression;
expression is first evaluated and then its value is returned to the caller

13. Argument Promotion Coercion of arguments
_______________ arguments to appropriate type to pass to method System.out.println( Math.sqrt( 4 ) );
Evaluates Math.sqrt( 4 )
Then evaluates System.out.println()

14. Argument Promotion Promotion rules
Specify how to convert types without data loss

15. Java API Packages
_______________ classes grouped into categories of related classes
Called packages
Called the Java Application Programming Interface (API)
Note the often used API packages

16. Random-Number Generation
Consider the random method in the Math class
Generates a random double 0 <= n < ______
The number can be manipulated and cast as an ______ to get desired range
For the roll of a die 1 + (int) (Math.random() * 6)
Note Figure 6.7 and Figure 6.8

17. Game of Chance Rules for "Craps" Roll dice first time
If sum equals 7 or 11, the player _________
If sum equals ____________, the player loses
Any other sum (4, 5, 6, 8, 9, 10) is that player’s point
Keep rolling dice until…
Sum matches player point
Player wins
Sum equals _______
Player loses

18. Game of Chance Note the adapted version of Figure 6.9 Note
An application
Note
_____________ class variables
Public methods
The __________________ function requires Character. (a non instantiating class)

19. Scope of Declarations
Scope of a ______________ is body of method where declaration appears
Scope of local variable is from point of declaration to end of ________________
Scope of label in labeled break/continue is statement enclosed by labeled statement
Scope of local-variable in initialization of for( ) is for _______________________ and rest of header
Scope of method or field of class is body of ____________

20. Shadowing
A field is shadowed (or hidden) if a _____________ variable or parameter has the same name as the field
This lasts until the local variable or parameter goes out of ______________
View example
Figure Variables with different scopes
Figure Test program

21. Method Overloading
Multiple methods with _____________ can be declared in same class
Methods must have different ___________
Different numbers, types, order of parameters
Example
Figure Overload example class
Figure Overload test program

22. Recursion Recursive method
Calls ___________ (directly or indirectly) through another method
Method knows how to solve only a ______ case
Method divides problem
Base case
Simpler problem – Method now divides simpler problem until solvable
Recursive call
Recursive step

23. Recursive Evaluation of 5!
Final value = 120 5! 5!
5! = 5 * 24 = 120 is returned
5 * 4!
2! = 2 * 1 = 2 is returned
5 * 4!
4! = 4 * 6 = 24 is returned
4 * 3!
4 * 3!
3! = 3 * 2 = 6 is returned
3 * 2!
3 * 2!
2 * 1!
2 * 1!
1 returned 1 1
(a) Sequence of recursive calls.
(b) Values returned from each recursive call.

24. Recursive Factorial Program
Function factorial() in Figure 6.15
Note
Initial call to factorial()
____________ or base case
Recursive call

25. Recursive Fibonacci Program
Consider function from program    public long fibonacci( long n )    {       // base case       if ( n == 0 || n == 1 )           return n;       // recursive step       else          return fibonacci( n - 1 ) + fibonacci( n - 2 );    }  // end method fibonacci
Note why this would be extremely _________

26. Recursive Fibonacci Program
return
fibonacci( 2 ) +
fibonacci( 1 )
return
fibonacci( 1 ) +
fibonacci( 0 )
return 1
return 1
return 0

27. Recursion vs. Iteration
Both the recursive functions shown can be done with either for or while loops
In fact they are done more efficiently ____________
Recursion has overhead
Processor time
Memory space
General rule: If it can be done either recursively or iteratively … choose __________