Work with Data and Decision Structure

Murach’s Java SE 6, C3© 2007, Mike Murach & Associates, Inc. Slide 2

Murach’s Java SE 6, C3© 2007, Mike Murach & Associates, Inc. Slide 3

Murach’s Java SE 6, C3© 2007, Mike Murach & Associates, Inc. Slide 4

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Murach’s Java SE 6, C3© 2007, Mike Murach & Associates, Inc. Slide 6

Murach’s Java SE 6, C3© 2007, Mike Murach & Associates, Inc. Slide 7 Enter Floating and Long Integer Values

Murach’s Java SE 6, C3© 2007, Mike Murach & Associates, Inc. Slide 8

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Decision Structure

Decision: Action based on condition Examples Simple condition: – If total sales exceeds $300 then applies 5% discount; otherwise, no discount. More than one condition: Taxable Income < =3000 no tax 3000 < taxable income <= % tax Taxable income > % tax Complex condition: – If an applicant’s GPA > 3.0 and SAT > 1200: admitted

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Murach’s Java SE 6, C2© 2007, Mike Murach & Associates, Inc. Slide 19

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Example: If total sales is larger than 1000, then give 5% discount Scanner sc = new Scanner(System.in); double totalSales; double discountRate=0; System.out.println("Enter a total sales: "); totalSales=sc.nextDouble(); if (totalSales > 1000) discountRate=0.05; double netPay=totalSales*(1-discountRate); System.out.println("Net pay is: " + netPay); double discountRate; System.out.println("Enter a total sales: "); totalSales=sc.nextDouble(); if (totalSales > 1000) discountRate=0.05; else discountRate=0;

Example: If with a block of statements if (totalSales > 1000) { discountRate=0.05; System.out.println("Thank you so much! "); } else { discountRate=0; System.out.println("Thank you! "); }

Variable Scope Block-level scope: declared within a block of code. Method (Procedural) level scope: declared in a procedure Class-level: declared in a class but outside any procedure.

Scanner sc = new Scanner(System.in); System.out.println("Enter a city name"); String City=sc.next(); if (City.equalsIgnoreCase("Paris")) { String Country="France"; System.out.println("It is in " + Country); } else System.out.println("It is not in France");

What output you will see? public class Main { public static String projLevelVar="Project level"; String testVar="Class Level Var"; public static void main(String[] args) { demoScope(); } public static void demoScope(){ String testVar="Method Level Var"; System.out.println(testVar); }

More than one condition Rules for bonus: JobCode = 1300 JobCode = 2500 JobCode = 3700 JobCode = 41000

Scanner sc = new Scanner(System.in); double jobCode, bonus; System.out.println("Enter job code: "); jobCode = sc.nextDouble(); if (jobCode==1) bonus=300; else if (jobCode==2) bonus=500; else if (jobCode==3) bonus=700; else bonus=1000; System.out.println("Bonus is: " + bonus);

Murach’s Java SE 6, C2© 2007, Mike Murach & Associates, Inc. Slide 30

Example Electric Company charges customers based on KiloWatt-Hour used. The rules are: – First 100 KH,20 cents per KH – Each of the next 200 KH ( up to 300 KH), 15 cents per KH – All KH over 300, 10 cents per KH

Murach’s Java SE 6, C4© 2007, Mike Murach & Associates, Inc. Slide 32 Case Structure with the Switch Statement

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Code Examle switch((int) jobCode) { case 1: bonus=300; case 2: bonus=500; case 3: bonus=700; case 4: bonus=1000; default: bonus=0; }

Explicit Casting Since the Switch structure requires an integer expression and the jobCode is declared as a double, we need to convert it to integer: From double to integer: int code = (int) jobCode From integer to double: int counter = 0; double dcounter = (double) counter;

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Murach’s Java SE 6, C4© 2007, Mike Murach & Associates, Inc. Slide 38

Nested if statements if (customerType.equals("R")) { // begin nested if if (subtotal >= 100) discountPercent =.2; else discountPercent =.1; } // end nested if else discountPercent =.4;

Type = “R” Or not Discount=.2Subtota>=100? Discount=.1 Discount=.4

Example State University calculates students tuition based on the following rules: – State residents: Total units taken <=12, tuition = 1200 Total units taken > 12, tuition = per additional unit. – Non residents: Total units taken <= 9, tuition = 3000 Total units taken > 9, tuition = per additional unit.

Decision Tree Resident or Not Units <= 12 or Not Units <= 9 or Not

Consider the following code snippet. if (aNumber >= 0) if (aNumber == 0) System.out.println("first string"); else System.out.println("second string"); System.out.println("third string"); Does the “else” pair with the first or the second if? What output do you think the code will produce if aNumber is 3?

Complex Condition University admission rules: Applicants will be admitted if meet one of the following rules: – 1. Income >= 100,000 – 2. GPA > 2.5 AND SAT > 900 An applicant’s Income is 150,000, GPA is 2.9 and SAT is 800. Admitted? – Income >= 100,000 OR GPA > 2.5 AND SAT >900 How to evaluate this complex condition?

Scholarship: Business students with GPA at least 3.2 and major in Accounting or CIS qualified to apply: – 1. GPA >= 3.2 – 2. Major in Accounting OR CIS Is a CIS student with GPA = 2.0 qualified? – GPA >= 3.2 AND Major = “Acct” OR Major = “CIS” Is this complex condition correct?

Examples SAT = 800, Income 60,000, GPA 3.0, admitted? – (SAT > 900 OR Income >= 50,000) AND Not GPA < 2.5 A=2, B=3 – (A=3 OR NOT (B < A)) AND B=A+1

NOT Set 1: Young: Age < 30 Set 2: Rich: Income >= 100,000 YoungRich

Condition with Not University admission rules: Applicants will be admitted if meet all the rules: – 1. SAT > 900 OR Income >= 50,000 – 2. Not GPA < 2.5 Condition: – SAT > 900 OR Income >= 50,000 AND Not GPA < 2.5 – Correct?

Order of Evaluation 1. () 2. Not 3. AND 4. OR

Examples SAT = 800, Income 60,000, GPA 3.0, admitted? – (SAT > 900 OR Income >= 50,000) AND Not GPA < 2.5 A=2, B=3 – (A=3 OR NOT (B < A)) AND B=A+1

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Murach’s Java SE 6, C4© 2007, Mike Murach & Associates, Inc. Slide 52

Examples SAT = 800, Income 60,000, GPA 3.0, admitted: – (SAT > 900 | Income >= 50,000) & !GPA < 2.5 GPA >= 3.2 AND (Major = “Acct” OR Major = “CIS”) – GPA>=3.2 & (Major.equals(“Acct”) | Major.equals(“CIS”)) (A=3 OR NOT (B < A)) AND B=A+1 – (A==3 | !(B < A)) & B=A+1