Arrays

1. Arrays

2. Exam 1 1. Java source and executable files have the following extensions? a. .java and .class b. .src and .class c. .javadoc and .exe d. .list and .exe

3. Exam 1 2. Which of the following is a Java comment a. ; This is my first program b. # This is my first program c. /* This is my first program */ d. ‘ This is my first program e. none of the above

4. Exam 1 3. We use the following operator to create a new object in Java a. malloc b. new c. string d. newObject

5. Exam 1 4. Commands to compile and execute a java program are a. run and java b. execute and javac c. javac and java d. compile and run

6. Exam 1 5. Identifiers may start with a. $ b. @ c. a number d. &

7. Exam 1 6. It is necessary to declare an object before you can use it a. True b. False

8. Exam 1 7. Which of the following is a valid identifier? a. Bank Account b. bank account c. bank$account d. bank-account

9. Exam 1 8. A series of characters that appear in double quote is a char data type a. True b. False

10. Exam 1 9. boolean isDone == false; is a valid assignment statement in Java a. True b. False

11. Exam 1 10. Which of the following is a correct variable declaration statement? a. int x - float y; b. int x: float y; c. int x,y; d. Long int x;

12. Exam 1 11. Boolean expressions are built by use of _relational______operators and _boolean_______operators 12. A data value that can not be changed is called __constant____________ 13. $Bad-Variable is __bad/invalid/not _ Java identifier.

13. Exam 1 14. These two data types: __float__, and ___double___are used for real numbers 15. _An object____is an instance of a class

14. Exam 1 16. double loanPeriod; if (loanPeriod < 0 || >1000 ); { System.out.println(“Loan period is invalid”); System.exit(1); } • loanPeriod is not initialized • loanPeriod or a variable name is missing • ; is not needed.

15. Exam 1 17. double s; s = 1.0; switch (s) { case 1.0: System.out.println(“ March madness”); break; case 2.0: System.out.println(“ November rain”); break; case 3.0: System.out.println(“White Christmas”); break; default: System.out.println(“No Special name”); break; } 1. Switch doesn’t support double data type

16. Exam 1 18. char aChar = ”NFL Championship”; • Char datatype can only contain 1 character • Char data type needs single quotes instead of double ones

17. Exam 1 19. int i, j; double x,y; i=1; j=2; x= Math.pow(3, (i/j)); y = x % 2; if (y ==0) System.out.println(x +" is an even number "); else System.out.println(x +" is an odd number"); ½ = 0, 30=1.0 y = 1.0 % 2 = 1.0 1.0 is an odd number

18. Exam 1 20. int count=1, sum=0; while (count < 9) { if (count % 2 != 0) { sum += count; } count++; } System.out.println(" Sum ="+ sum);

19. Exam 1 count =1, sum =0, 1 %2 = 1 (!= 0), sum = 0+1=1 count =2, sum=1, 2 % 2 = 0 count =3, sum=1, 3 % 2 = 1 (!=0), sum = 1+3 = 4 count =4, sum=4, 4 % 2 = 0 count =5, sum=4, 5 % 2 = 1 (!=0), sum = 4+5 = 9 count =6, sum=9, 6 % 2 = 0 count =7, sum=7, 7 % 2 = 1 (!=0), sum = 9+7 = 16 count =8, sum=16, 8 % 2 = 0 count =9, exit Sum = 16

20. Exam 1 21. int sum =0; for (int i=1; i<=2; i++) { for (int j=1; j<=3; j++) { sum = sum + (i+j); } } System.out.println(" Sum ="+ sum);

21. Exam 1 sum =0 i=1; j=1; sum=0+(1+1) j=2; sum =(1+1)+(1+2) j=3; sum = (1+1)+(1+2)+(1+3) = 2+3+4=9 i=2 j=1; sum=9+(2+1) j=2; sum=9+(2+1)+(2+2) j=3; sum=9+(2+1)+(2+2)+(2+3)= 9+(3+4+5)=9+12=21 Sum =21

22. Lab 4

23. Project Discussion (section 01+02) • Loan class: public class Loan{ // data members // constructor(s) // Methods() }

24. Project Discussion (section 01) • Loan class: public class Loan{ // data members private int loanPeriod; private double loanAmount; private double monthlyInterestRate; private double monthlyAmortization; // optional }

26. Project Discussion (section 01) • Loan class: public class Loan{ //Constructor(s) public Loan(double loanAmt, double interest, int months ) { // this is a stub loanAmount = loanAmt; // should initialize monthlyInterestRate and //loanPeriod the same way } }

27. Project Discussion (section 01) • Loan class: public class Loan{ // Methods public void setLoanAmount(double loanAmt) { // this is stub } public double getLoanAmount() { return loanAmount; } }

28. Project Discussion (section 01) • Loan class: public class Loan{ // Methods public void setMonthlyInterestRate(double interest) { // this is stub } public double getMonthlyInterestRate() { return monthlyInterestRate; } }

29. Project Discussion (section 01) • Loan class: public class Loan{ // Methods public void set(int months) { // this is stub } public double getLoanPeriod() { return loanPeriod; } }

30. Project Discussion (section 01) • Loan class: public class Loan{ // Methods public double computeAmortization() { // this is a stub // The formula should be put here // Make sure to change the names to the data // member name // Don’t forget return ……; } }

31. Project 2 (Section 01) public class Amortization{ // data member; private Loan loan; // constructor public Amortization () { } }

32. Project 2 (Section 01) public class Amortization{ // Methods: public void start() { // This is a stub } public void describeProgram() { // This is a stub } }

33. Project 2 (Section 01) public class Amortization{ // Methods: public void getInput () { // This is a stub // You should use Loan class here } public void displayOutput() { // This is a stub // You should use Loan class here } }

34. Lesson plan • Arrays

35. Section 02 public class Loan { // data members private double monthlyInterestRate; private double loanAmount; private int numberOfMonths; }

36. Section 02 public class Loan { // Constructor(s) public Loan(double borrowedAmt, double interest, int months) { // this is a stub loanAmount= borrowedAmt; // similarly, you can initialize monthlyInterestRate // and numberOfMonths accordingly } }

37. Project 2 (Section 02) public class Amortization{ // data member private Loan loan; }

38. Project 2 (Section 02) public class Amortization{ // constructor public Amortization() { // this is a stub loan = new Loan(1000,0.1,12); } }

39. Project 2 (Section 02) public class Amortization{ // methods public void start() { // this is a stub } private/public void describeProgram() { // this is a stub // Cut and paste System.out.print describe what // this program is doing from project 1 to here } }

40. Project 2 (Section 02) Import javax.swing.*; public class Amortization{ // methods public/private void getInput() { // this is a stub // Cut and paste the while loop to get inputs users in part e (project 1) here // Use Loan Class loan.setBorrowedMoney( …..); } }

41. Project 2 (Section 02) Import javax.swing.*; public class Amortization{ // methods public/private void printOutput() { // This is a stub // print out loan. // getAmortizationPayment() } }

42. Section 02 public class Loan { //Methods public void setBorrowedMoney(double principle) { // this is a stub } public double getBorrowedMoney() { return loanAmount; } }

43. Section 02 public class Loan { //Methods public void setMonthlyInterestRate(double interest) { // this is a stub } public double getMonthlyInterestRate() { return monthlyInterestRate; } }

44. Section 02 public class Loan { //Methods public void setNumberOfMonths(int months) { // this is a stub } public double getNumberOfMonths() { return months; } }

45. Section 02 public class Loan { //Methods public double getAmortizationPayment() { // this is a stub // You should put the formula in project 1 here // Don’t forget to change the variable names // and don’t forget to return the value; return ……; } }

46. Arrays • We often need to group together related items of data. • Cards in a pack. • Ships in a port. • Java provides two distinct facilities: • Traditional array. • Flexible-size collection classes (java.util).

47. Problems That Arrays Solve …… minValue = firstNumber; if (secondNumber < minValue) minValue = secondNumber; if (thirdNumber < minValue) minValue = thirdNumber; if (fourthNumber < minValue) minValue = fourthNumber; if (fifthNumber < minValue) minValue = fifNumber; …… What is this code doing? Finding minimum value from a set of 5 values

48. Arrays for Numerical data type (primitive data types) int[] number = new int [5]; int minValue; String inputStr; for (int i=0; i<5; i++) { inputStr = JOptionPane.showInputDialog(null,"Please enter the value for element "+i); number[i] = Integer.parseInt(inputStr); } minValue = number[0]; for (int i=1; i<5; i++) { if (minValue > number[i]) minValue = number[i]; } System.out.println(" minValue ="+ minValue); Array declaration & allocation memory

49. Arrays for Numerical data type (primitive data types) Getting values for all elements in the array int[] number = new int [5]; int minValue; String inputStr; for (int i=0; i<5; i++) { inputStr = JOptionPane.showInputDialog(null,"Please enter the value for element "+i); number[i] = Integer.parseInt(inputStr); } minValue = number[0]; for (int i=1; i<5; i++) { if (minValue > number[i]) minValue = number[i]; } System.out.println(" minValue ="+ minValue);

50. Arrays for Numerical data type (primitive data types) int[] number = new int [5]; int minValue; String inputStr; for (int i=0; i<5; i++) { inputStr = JOptionPane.showInputDialog(null,"Please enter the value for element "+i); number[i] = Integer.parseInt(inputStr); } minValue = number[0]; for (int i=1; i<5; i++) { if (minValue > number[i]) minValue = number[i]; } System.out.println(" minValue ="+ minValue); Access each element of an array