Introduction to Java Programming Solutions Chapter 3 and 4

Exercises book

Review Questions

4.7

Computing a sales commission given the sales amount and the commission rateAnswer: non-void method with return type double

Printing a calendar for a monthAnswer: void method

Computing a square rootAnswer: non-void method with return type double

Testing whether a number is even and return true if it isAnswer: non-void method with return type boolean

Printing a message for a specified number of timesAnswer: void method

Computing the monthly payment, given the loan amount, number of years, annual interest rate.Answer: non-void method with return type double.

Finding the corresponding uppercase letter given a lowercase letter.Answer: non-void method with return type char.

4.8

Line 2: method1 is not defined correctly. It does not have a return type or void.Line 2: type int should be declared for parameter m.Line 8: parameter type for n should be double to match xMethod(3.4).Line 11: if (n

4.15

Line 8: int n = 1 is wrong since n is already declared in the method signature.

4.20

The output is 15 (5+ 4+ 3+ 2+ 1 = 15).

Programming Questions

3.30

public class Exercise3_30 {

public static void main(String[] args) {int n = 1000;

// useful variablesdouble num = 1.0;double denom = 1.0;// initialisation:double pi = 0.0;

for (int i = 0; i

3.31

public class Exercise3_31 {

public static void main(String[] args) {int n = 1000;

double denom = 1.0;// initialisation:double e = 1.0;

for (int i = 1; i 0) {

sum += (int) (n % 10);n = n / 10;

}return sum;

}

public static void main(String[] args) {long number = 13209643;System.out.println("Sum of digits of " + number + " is: "

+ sumDigits(number));}

}

3

4.6

public class Exercise4_6 {

public static int min(int m, int n) {if (m < n) return m;else return n;

}

public static int gcd(int m, int n) {int gcd = min(m, n);while (m % gcd != 0 || n % gcd != 0) {

gcd--;}return gcd;

}

public static void main(String[] args) {int number1 = 25;int number2 = 20;System.out.println("gcd of " + number1 + " and "+ number2 + " is: " + gcd(number1, number2));

}}

4

4.22

public class Exercise4_22 {

public static int min(int m, int n) {if (m < n) return m;else return n;

}

public static int max(int m, int n) {if (m > n) return m;else return n;

}

public static int gcd(int m, int n) {int min = min(m, n);int max = max(m, n);if (max % min == 0) return min;else return gcd(min, max % min);

}

public static void main(String[] args) {int number1 = 25;int number2 = 20;System.out.println("gcd of " + number1 + " and "+ number2 + " is: " + gcd(number1, number2));

}}

4.24

public class Exercise4_24 {

public static int sumDigits(long n) {if (n / 10 == 0) return (int) n;else return (int)(n % 10) + sumDigits(n / 10);

}

public static void main(String[] args) {long number = 13209643;System.out.println("Sum of digits of " + number + " is: "

+ sumDigits(number));}

}

5

Extra exercise

/*** This class contains a solution to the Extra Exercise of chapter 4.

* @author Marko Boon

*/

public class TaylorExercise {

/*** Computes sin(x) using a Taylor series approximation of order n.

* @param x the coordinate where the sinus function should be evaluated

* @param n the order of the Taylor series.

* @return sin(x) using a Taylor series approximation

*/

public static double sin(double x, int n) {double s = 0;// PRECONDITION: ratio = +/- x^k / k!double ratio = x;for (int k = 1; k