Question

Random Number Generation and Static Methods

Write a program that simulates the flipping of a coin n-times to see how often it comes up heads or tails. Ask the user to type in the number of flips (n) and print out the number of times the coin lands on head and tail. Use the method ‘random()’ from the Math class to generate the random numbers, and assume that a number less than 0.5 represents a tail, and a number bigger than or equal to 0.5 represents a head. Demo this before moving on to the next part.

Next, you are going to simulate rolling a 6-sided die several times and computing the sum of all the landings. Follow the steps below:

a- Write a static method called ‘sum_of_rolls’ that takes the number of times (m) you want to roll the die as an argument and returns the sum of all the landings. Set-up a loop inside this method that iterates exactly m times, and each time through the loop generate a random integer between 1 and 6, print that number out and also add it to the running total. Return the running total when the loop ends. This method doesn’t print the running total.

b- Now, add a couple of lines of code at the bottom of your main method to do the following: prompt for and read in the number of rolls; call the method ‘sum_of_rolls’; and then print out the returned value.

Include a loop in the program to allow the user to repeat the above steps as often as (s)he wishes. Demo this before moving on to the next part.

Sample Input/Output:

Programmer: Name of the programmer (your name) Course: COSC 111

Due date: 4-3-2019

Lab#: 8, part #1

Enter the number of flips: 20

Number of heads: 13

Number of tails: 7

Enter the number of rolls: 10

3 4 2 5 1 1 5 2 5 4

Sum of rolls = 32

Do it again, (yes or no)? Yes

Answer 1

import java.util.Random;

import java.util.Scanner;

public class Flipcoin {

static boolean flipCoin() {

if (Math.random() < 0.5)

return false;

else

return true;

}

static int sum_of_rolls(int n) {

Random r = new Random();

int sum = 0;

for (int i = 0; i < n; ++i) {

int roll = r.nextInt(6) + 1;

System.out.print(roll + " ");

sum = sum + roll;

}

System.out.println();

return sum;

}

public static void main(String[] args) {

Scanner keyboard = new Scanner(System.in);

int n, heads = 0, tails = 0;

String str;

do {

System.out.print("Enter the number of flips: ");

n = keyboard.nextInt();

for (int i = 0; i < n; ++i) {

if (flipCoin())

++heads;

else

++tails;

}

System.out.println("Number of heads: " + heads);

System.out.println("Number of tails: " + tails);

System.out.print("Enter the number of rolls: ");

n = keyboard.nextInt();

System.out.println("Sum of rolls = " + sum_of_rolls(n));

System.out.println("Do it again, (yes or no)? ");

keyboard.nextLine();

str = keyboard.nextLine();

heads = 0; tails = 0;

} while (str.toLowerCase().equals("yes"));

}

}

===========================================
SEE OUTPUT

19 20 21 for Cint i-0; i< n; ++i)i <terminated> Flipcoin [Java Application] /Library/Java/JavaVirtualMac Enter the number of flips: 20 Number of heads: 11 Number of tails: 9 Enter the number of rolls: 10 3 261651461 Sum of rolls35 Do it again, (yes or no)? yes Enter the number of flips: 10 Number of heads: 4 Number of tails: 6 Enter the number of rolls: 5 4 15 5 1 Sum of rolls 16 Do it again, (yes or no)? int rollr.nextInt(6)+1; System. out.print(roll " "); sum = sum + roll; 23 System.out.printlnO; return sum; 25 26 27 28 public static void main(String[] args) [ 29 0,30 31 32 Scanner keyboardnew Scanner(System. in); int n, heads -0, tails-0; String str; 34 35 36 37 38 39 40 41 42 43 do System.out.print("Enter the number of flips: " 0 nkeyboard.nextIntO); for (inti-0; i < n; +-i) if (flipCoin)) ++heads; else ++tails; System. out.println(" Number of heads: " + heads) System. out.printlnC"Number of tails:" + tails) 45 46 47 48 49 50 System. out.printC"Enter the number of rolls: " nkeyboard.nextIntO; 52 53 54 System.out.printlnC" Sum of rolls "Sum_of_r System.out.printlnC"Do it again, Cyes or no)? keyboard.nextLine str-keyboard.nextLineO; heads 0; tails0; ł while (str.toLowerCase(.equalsC"yes")); 56 57 58 59


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