Fall Semester 2022-2023
INT201 Object Oriented Programming
Tutorial Sheet#1 - Solution
Week Starting, September 5, 2022
Ex#1
Write a method that takes as input a sentence and returns the number of vowels in the sentence.
Write a driver program to test your method. Vowel letters are (a, e, i, o u).
import java.util.*;
import static java.lang.Character.*;
public class TutorialSheet1_EX1 {
static Scanner keyboard = new Scanner(System.in);
public static void main(String[] args) {
String text;
int counter=0;
System.out.println("Enter a sentence:");
text = keyboard.nextLine();
counter = countVowels(text);
System.out.println("Number of vowel letters:" + counter);
}
public static int countVowels(String str) {
int len = str.length();
int count =0;
char ch;
for (int i=0; i<len; i++){
ch = str.charAt(i);
ch=toUpperCase(ch);
switch (ch) {
case 'A':
case 'E':
case 'I':
case 'O':
case 'U':count++;
break;
default:
}
}
return (count);
}//End of method countVowels
}
Ex#2
Write a method that takes three integers as parameters (, int a, int b, and int c ) that represent the
coefficients of a quadratic equation and return the largest of the two roots of the quadratic equation.
The roots are computed using the following formulas:
x1 = (-b + square root (b2 – 4*a*c))/(2*a)
x2 = (-b - square root (b2 – 4*a*c))/(2*a)
Write a driver program to test your method.
In running your program, use the following values for the coefficients:
Case 1: a = 1, b = -8, c = 15
Case 2: a = 1, b = -4, c = 4
Case 2: a = 10, b = -17, c = 6
import java.util.*;
import static java.lang.Math.*;
public class TutorialSheet1_EX2{
public static Scanner user = new Scanner(System.in);
public static void main(String[] args){
int a, b, c;
double maxRoot;
System.out.println("Enter a, b, and c coefficients of quadratic
equation: ");
a = user.nextInt();
b = user.nextInt();
c = user.nextInt();
maxRoot = findMaxRoot(a, b, c);
if(maxRoot != -9999)
System.out.println("Max root: " + maxRoot);
else
System.out.println("Roots are complex");
}
public static double findMaxRoot(int ca, int cb, int cc){
double x1, x2, max;
double dis;
dis = cb*cb-4.0*ca*cc;
if(dis >=0){
x1 = (-cb - sqrt(dis))/(2.0*ca);
x2 = (-cb + sqrt(dis))/(2.0*ca);
max = x1;
if(x2 > max)
max = x2;
}
else
max=-9999.0;
return(max);
}
}
Ex#3
Write a method that takes two words as parameters (passed as of type String) and returns the
number of characters in the smaller of the two words. Write a driver program to test your method.
import java.util.Scanner;
import java.lang.*;
public class TutorialSheet1_EX3
{
static Scanner s = new Scanner(System.in);
public static void main(String[] args) {
String word1, word2;
int numChar;
System.out.println("Enter first word: ");
word1 = s.next();
System.out.println("Enter second word: ");
word2 = s.next();
numChar = countSmallerWord(word1,word2);
System.out.println("The number of characters in the smaller
word: " + numChar);
} // End of main
public static int countSmallerWord(String str1, String str2)
{
if(str1.length() < str2.length())
return str1.length();
else
return str2.length();
} // End of method compareStrings
}
Ex#4
Write a method that generates three random integers between 1 and 50 and returns the average of
the three integers. Write a driver program to test your method.
import java.util.Scanner;
import static java.lang.Math.*;
public class TutorialSheet1_EX4
{
public static void main(String[] args)
{
System.out.printf("Average of three random numbers: %2.4f
\n",averageRandom());
}
public static double averageRandom() {
int n1, n2, n3;
double avg;
n1 = (int)(random()*50)+1;
n2 = (int)(random()*50)+1;
n3 = (int)(random()*50)+1;
avg = (n1+n2+n3)/3.0;
return avg;
}// End of method averageRandom
}
Ex#5
Write a method that takes two parameters of type double (the first represents interest rate and the
second represents investment) and returns the value of the investment after n years where n is an
integer parameter passed to the method (the method has three parameters). Write a driver program
to test your method.
Note: In = I1*(1+interestRate)n, where In: investment after n years, I1 : initial investment
Test your method with the following data:
Interest rate = 0.065, investment =10,000, and n = 10.
import java.util.*;
import static java.lang.Math.*;
public class TutorialSheet1_EX5
{
public static Scanner user = new Scanner(System.in);
public static void main(String[] args)
{
double investment, rate;
double final_amount;
int years;
double maxRoot;
System.out.println("Enter initial investment, interest rate, and
years: ");
investment = user.nextDouble();
rate = user.nextDouble();
years = user.nextInt();
final_amount = computeAmount(investment, rate, years);
System.out.printf("Amount after %3d years is %10.2f\nx",
years,final_amount);
}
public static double computeAmount(double invest, double intRate,
int numYears){
double amount;
amount = invest *pow(1.0+intRate,numYears);
return amount;
}
}