Chapter 3 Flow of Control - Orange Coast Collegefaculty.orangecoastcollege.edu/mmalaty/CS170/PDF/CS170_Ch03...JAVA: An Introduction to Problem Solving & Programming, ... An Introduction

JAVA: An Introduction to Problem Solving & Programming, 7th Ed. By Walter Savitch

ISBN-13: 9780133766264 © 2015 Pearson Education, Inc., Upper Saddle River, NJ. All Rights Reserved

Flow of Control

Chapter 3

Part 3 – The Switch Statement



Agenda

• Hw 03 comments

• Review of Ch03 - Parts 1 & 2

• Conditional operator

• I/O of boolean values

• The switch statement

• Random numbers

• Methods with arguments

CS 170 _ Java Programming - M. Malaty - Chapter 03:

Branching Slide # 2



The Conditional Operator – 1/2

• Used instead of writing a simple if statementif (n1 > n2)

max = n1;

else

max = n2;

▪ can be written as

max = (n1 > n2) ? n1 : n2;

• Needs three operands; the condition, and two

actions for true and false respectively

• The ? and : together are call the conditional

operator or ternary operator

CS 170 _ Java Programming - M. Malaty

Chapter 03: Branching - Slide # 3



The Conditional Operator – 2/2

• The conditional operator is useful with print

and println statements

• Example:

System.out.println("You worked " +

hours +

((hours > 1) ? “ hours" : “ hour"));





Input and Output of Boolean Values

• For output, just write the Boolean variable name

• For input, use the nextBoolean()method and save

the result into the Boolean variable

• Exampleboolean booleanVar = false;

System.out.println(booleanVar);

System.out.println("Enter a boolean value:");

Scanner keyboard = new Scanner(System.in);

booleanVar = keyboard.nextBoolean();

System.out.println("You entered " + booleanVar);





The switch Statement – 1/8

• The switch statement is a multiway branch

that makes a decision based on an integral

(integer or character) expression

▪ Java 7 allows String expressions as well

• Begins with the keyword switch followed by

an integral expression in parentheses and

called the controlling expression

• A list of cases follows, enclosed in braces






• Each case consists of the keyword case followed by▪ A constant called the case label▪ A colon (:)

▪ A list of statements▪ An optional break statement

• The list is searched for a case label matching the

controlling expression

• The action associated with a matching case label is executed

• If you do not add the break statement, control will

continue to the next case

• If no match is found in all case entries, the case labeled default is executed






• The default case is optional, but recommended, even if it simply prints a message

• Repeated case labels are not allowed

• Syntax:

switch (Controlling_Expression)

{

case Case_Label:

Statement(s);

break;

case Case_Label:

…

default:

…

}







switch Statement

Example

http://faculty.orangecoastcollege.edu/mmalaty/CS170/PDF/CodeSamples1.htm




• The action for each case typically ends with the word break

• The optional break statement prevents the

consideration of other cases

• The controlling expression can be anything

that evaluates to an integral type







• You can omit the break statement to simplify the

statements

• Example: Checking for upper- and lower-case responses that

are the same






• More examples from: http://math.hws.edu/javanotes/c3/s6.html


http://math.hws.edu/javanotes/c3/s6.html





• More examples from: http://math.hws.edu/javanotes/c3/s6.html







• More examples from: http://math.hws.edu/javanotes/c3/s6.html▪ Using strings





Switch Statement Videos

• thenewboston:

▪ Java Programming Tutorial - 12 - Switch Statement

(6:46)

• EJ Media:

▪ Java Tutorial for Beginners - 8 - Switch statements

(6:12)

• BrandonioProductions:

▪ Learning Java: Part 22: The Switch Statement

(17:08)


Branching Slide # 15

https://www.youtube.com/watch?v=RVRPmeccFT0

https://www.youtube.com/watch?v=QvrbN839IVM

https://www.youtube.com/watch?v=X6luWBTgtbs



Intro Methods with Arguments

• You can pass as many arguments to a java method

• You can return nothing (void) only one result from a

method of any data type

• Videos

▪ Learneroo

• Java Methods and Parameters (2:03)

▪ BrandonioProductions

• Learning Java: Part 5: Custom methods with return statements and

parameters (7:49)

▪ thenewboston

• Java Programming Tutorial - 15 - Use Methods with Parameters

(6:40)



https://www.youtube.com/channel/UChy5I0N5xQ3Y6gmgNOZv-UA

https://www.youtube.com/watch?v=DzsPkJQwXcQ

https://www.youtube.com/channel/UCRclYvtDY8M6gb2n8bcDlKA

https://www.youtube.com/watch?v=wtwiPCs7Q0E

https://www.youtube.com/channel/UCJbPGzawDH1njbqV-D5HqKw

https://www.youtube.com/watch?v=7MBgaF8wXls



Random Numbers -1/3• Random class

▪ Must import Random library

▪ Must create an object and apply the methods on that object

▪ More flexible

• Generates different data types

• Generates uniformly distributed random numbers

• Math.random() Method

▪ Returns a double value in the range 0.0 up to, but not including 1.0

• 0.0 <= x < 1.0

▪ Needs more work to translate into the desired range

• You can use

– multiplication to expand the range

– Addition to shift the range

– Casting to convert to integer

▪ No need to create an object

• Random class vs. Math.random() method

▪ Stack Overflow



http://stackoverflow.com/questions/738629/math-random-versus-random-nextintint



Random Numbers -2/3• Examples:

▪ generate a double between 0.0 and 10.0

• double randDouble = Math.random() * 10;

▪ generate a integer between 0 and 10

• int randInt = Math.round(Math.random() * 10);

• int randInt = (int) (Math.random() * 10);

• int randInt = Random.nextInt(10);

▪ Generate a range from 40.0 to 90.0

• double randDouble = Math.random() * 50 + 40;

▪ Generate a range from 50 to 99

• int randInt = (int) ( Math.random() * 50) + 50;

▪ General format:

• Return a random number between a and a+b, excluding a+b

• double randDouble = a + Math.random() * bCS 170 _ Java Programming - M. Malaty - Chapter 03:




Random Numbers -3/3

• Some videos:

▪ Adam Gaweda:

• Using Java's Math.random() Method (5:12)

▪ The Java Hub - Free Tutorials

• Java for the Absolute Beginner - #14 - Random Numbers (7:08)– Dice uses loops & Random class

▪ TheNewBoston:

• Java Programming Tutorial - 26 - Random Number Generator (5:14)– Dice uses loops & Random class

▪ BrandonioProductions:

• Learning Java: Part 8: Generating Random Numbers (3:55)

▪ OnliveGamer

• Java Tutorial 8 - Random Number Generator (7:56)

▪ TheKaleb32

• How to Generate Random Numbers in Java (10:35)



https://www.youtube.com/channel/UCBgSCTqTUk5PrItkQF4bjSA

https://www.youtube.com/watch?v=o-A-M6syLI4

https://www.youtube.com/channel/UCBgSCTqTUk5PrItkQF4bjSA

https://www.youtube.com/watch?v=tcK0X6aW42I

https://www.youtube.com/watch?v=AhwIYAXPASw

https://www.youtube.com/watch?v=kHcVnNCbEBs

https://www.youtube.com/watch?v=D3IfRpjKJJk

https://www.youtube.com/watch?v=SQhJBC4oJ9Y



Summary

• You have learned about▪ Conditional operator

▪ The type boolean

▪ I/O of boolean values

▪ Java switch statement

▪ Random class



Documents

Chapter 3 Flow of Control - Orange Coast Collegefaculty.orangecoastcollege.edu/mmalaty/CS170/PDF/CS170_Ch03...JAVA: An Introduction to Problem Solving & Programming, ... An Introduction