This is in java and need a comment. Task #1 The while Loop 1. Copy the file Dice
ID: 3673000 • Letter: T
Question
This is in java and need a comment.
Task #1 The while Loop
1. Copy the file DiceSimulation.java (see Code Listing 4.1) from the Student CD or as directed by your instructor. DiceSimulation.java is incomplete. Since there is a large part of the program missing, the output will be incorrect if you run DiceSimulation.java.
2. I have declared all the variables. You need to add code to simulate rolling the dice and keeping track of the doubles. Convert the algorithm below into Java code and place it in the main method after the variable declarations, but before the output statements. You will be using several control structures: a while loop and an if-else-if statement nested inside another if statement. Use the indenting of the algorithm to help you decide what is included in the loop, what is included in the if statement, and what is included in the nested if-else-if statement.
3. To "roll" the dice, use the nextInt method of the random number generator to generate an integer from 1 to 6.
Repeat while the number of dice rolls are less than the number of times the dice should be rolled.
Get the value of the first die by "rolling" the first die
Get the value of the second die by "rolling" the second die
If the value of the first die is the same as the value of the second die
If value of first die is 1
Increment the number of times snake eyes were rolled
Else if value of the first die is 2
Increment the number of times twos were rolled
Else if value of the first die is 3
Increment the number of times threes were rolled
Else if value of the first die is 4
Increment the number of times fours were rolled
Else if value of the first die is 5
Increment the number of times fives were rolled
Else if value of the first die is 6
Increment the number of times sixes were rolled
Increment the number of times the dice were rolled
4. Compile and run. You should get numbers that are somewhat close to 278 for each of the different pairs of doubles. Run it several times. You should get different results than the first time, but again it should be somewhat close to 278.
Task #2 Using Other Types of Loops
1. Change the while loop to a do-while loop. Compile and run. You should get the same results.
2. Change the do-while loop to a for loop. Compile and run. You should get the same results.
Task #3 Writing Output to a File
1. Copy the files StatsDemo.java (see Code Listing 4.2) and Numbers.txt from the Student CD or as directed by your instructor.
2. First we will write output to a file:
a. Create a FileWriter object passing it the filename Results.txt (Don’t forget the needed import statement).
b. Create a PrintWriter object passing it the FileWriter object.
c. Since you are using a FileWriter object, add a throws clause to the main method header.
d. Print the mean and standard deviation to the output file using a three decimal format, labeling each.
e. Close the output file.
3. Compile, debug, and run. You will need to type in the filename Numbers.txt. You should get no output to the console, but running the program will create a file called Results.txt with your output. The output you should get at this point is: mean = 0.000, standard deviation = 0.000. This is not the correct mean or standard deviation for the data, but we will fix this in the next tasks.
Task #4 Calculating the Mean
1. Now we need to add lines to allow us to read from the input file and calculate the mean.
a. Create a FileReader object passing it the filename.
b. Create a BufferedReader object passing it the FileReader object.
2. Write a priming read to read the first line of the file.
3. Write a loop that continues until you are at the end of the file.
4. The body of the loop will:
a. convert the line into a double value and add the value to the accumulator
b. increment the counter
c. read a new line from the file
5. When the program exits the loop close the input file.
6. Calculate and store the mean. The mean is calculated by dividing the accumulator by the counter.
7. Compile, debug, and run. You should now get a mean of 77.444, but the standard deviation will still be 0.000.
Task #5 Calculating the Standard Deviation
1. We need to reconnect to the file so we can start reading from the top again.
a. Create a FileReader object passing it the filename.
b. Create a BufferedReader object passing it the FileReader object.
2. Reinitialize the sum and count to 0.
3. Write a priming read to read the first line of the file.
4. Write a loop that continues until you are at the end of the file.
5. The body of the loop will:
a. convert the line into a double value and subtract the mean, store the result in difference
b. add the square of the difference to the accumulator
c. increment the counter
d. read a newline from the file.
6. When the program exits the loop close the input file.
7. The variance is calculated by dividing the accumulator (sum of the squares of the difference) by the counter. Calculate the standard deviation by taking the square root of the variance (Use the Math.sqrt method to take the square root).
8. Compile, debug, and run. You should get a mean of 77.444 and standard deviation of 10.021.
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/
/
/
Modification to the Lab 4 instructions:
Task 1 says to create a while loop to implement the algorithm
Task 2 says to replace the while loop with a do/while loop. Then replace the do/while loop with a for loop.
The modification I want you to do to this lab, is to create the while loop as instructed. But then do not replace the while loop, leave it in place, but then add the do/while loop below the printout lines and then copy the printout lines below the do/while loop. Then add the for loop below that, and copy the printout lines below the for loop. Don’t forget to set the accumulator variables to 0 between each loop.
So what should happen is that when this program is run, there should be a set of printouts for the results of the while loop, then there should be a set of printouts for the do/while loop, then a set of printouts for the for loop.
So, this should get repeated 3 times, once for each type of loop:
Repeat while the number of dice rolls are less than the number of times the dice should be rolled.
Get the value of the first die by "rolling" the first die
Get the value of the second die by "rolling" the second die
If the value of the first die is the same as the value of the second die
If value of first die is 1
Increment the number of times snake eyes were rolled
Else if value of the first die is 2
Increment the number of times twos were rolled
Else if value of the first die is 3
Increment the number of times threes were rolled
Else if value of the first die is 4
Increment the number of times fours were rolled
Else if value of the first die is 5
Increment the number of times fives were rolled
Else if value of the first die is 6
Increment the number of times sixes were rolled
Increment the number of times the dice were rolled
System.out.println ("You rolled snake eyes " + snakeEyes +
" out of " + count + " rolls.");
System.out.println ("You rolled double twos " + twos +
" out of " + count + " rolls.");
System.out.println ("You rolled double threes " + threes +
" out of " + count + " rolls.");
System.out.println ("You rolled double fours " + fours +
" out of " + count + " rolls.");
System.out.println ("You rolled double fives " + fives +
" out of " + count + " rolls.");
System.out.println ("You rolled double sixes " + sixes +
" out of " + count + " rolls.");
Also, add a printout of some kind between the loop printouts to show where one loops printouts end and the next one begins. Something like:
System.out.println("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
/
/
/
/
Code Listing 4.1 (DiceSimulation.java)
import java.util.Random; // Needed for the Random class
/**
This class simulates rolling a pair of dice 10,000 times
and counts the number of times doubles of are rolled for
each different pair of doubles.
*/
public class DiceSimulation
{
public static void main(String[] args)
{
final int NUMBER = 10000; // Number of dice rolls
// A random number generator used in
// simulating the rolling of dice
Random generator = new Random();
int die1Value; // Value of the first die
int die2Value; // Value of the second die
int count = 0; // Total number of dice rolls
int snakeEyes = 0; // Number of snake eyes rolls
int twos = 0; // Number of double two rolls
int threes = 0; // Number of double three rolls
int fours = 0; // Number of double four rolls
int fives = 0; // Number of double five rolls
int sixes = 0; // Number of double six rolls
// TASK #1 Enter your code for the algorithm here Copyright © 2016 Pearson Education, Inc., Hoboken NJ
// Display the results
System.out.println ("You rolled snake eyes " +
snakeEyes + " out of " +
count + " rolls.");
System.out.println ("You rolled double twos " +
twos + " out of " + count +
" rolls.");
System.out.println ("You rolled double threes " +
threes + " out of " + count +
" rolls.");
System.out.println ("You rolled double fours " +
fours + " out of " + count +
" rolls.");
System.out.println ("You rolled double fives " +
fives + " out of " + count +
" rolls.");
System.out.println ("You rolled double sixes " +
sixes + " out of " + count +
" rolls.");
}
}
Code Listing 4.2 (StatsDemo.java)
import java.util.Scanner;
// TASK #3 Add the file I/O import statement here
/**
This class reads numbers from a file, calculates the
mean and standard deviation, and writes the results
to a file.
*/
public class StatsDemo
{
// TASK #3 Add the throws clause
public static void main(String[] args)
{
double sum = 0; // The sum of the numbers
int count = 0; // The number of numbers added
double mean = 0; // The average of the numbers
double stdDev = 0; // The standard deviation
String line; // To hold a line from the file
double difference; // The value and mean difference Copyright © 2016 Pearson Education, Inc., Hoboken NJ
// Create an object of type Scanner
Scanner keyboard = new Scanner (System.in);
String filename; // The user input file name
// Prompt the user and read in the file name
System.out.println("This program calculates " +
"statistics on a file " +
"containing a series of numbers");
System.out.print("Enter the file name: ");
filename = keyboard.nextLine();
// ADD LINES FOR TASK #4 HERE
// Create a FileReader object passing it the filename
// Create a BufferedReader object passing FileReader
// object
// Perform a priming read to read the first line of
// the file
// Loop until you are at the end of the file
// Convert the line to a double value and add the
// value to sum
// Increment the counter
// Read a new line from the file
// Close the input file
// Store the calculated mean
// ADD LINES FOR TASK #5 HERE
// Reconnect FileReader object passing it the
// filename
// Reconnect BufferedReader object passing
// FileReader object
// Reinitialize the sum of the numbers
// Reinitialize the number of numbers added
// Perform a priming read to read the first line of
// the file
// Loop until you are at the end of the file
// Convert the line into a double value and
// subtract the mean
// Add the square of the difference to the sum
// Increment the counter
// Read a new line from the file
// Close the input file
// Store the calculated standard deviation
// ADD LINES FOR TASK #3 HERE
// Create a FileWriter object using "Results.txt"
// Create a PrintWriter object passing the Copyright © 2016 Pearson Education, Inc., Hoboken NJ
// FileWriter object
// Print the results to the output file
// Close the output file
}
}
Explanation / Answer
task1:-
import java.util.Random;
public class DiceSimulation
{
public static void main(String[] args)
{
final int NUMBER = 10000;
int i=0;// Number of dice rolls
// A random number generator used in
// simulating the rolling of dice
Random generator = new Random();
int die1Value; // Value of the first die
int die2Value; // Value of the second die
int count = 0; // Total number of dice rolls
int snakeEyes = 0; // Number of snake eyes rolls
int twos = 0; // Number of double two rolls
int threes = 0; // Number of double three rolls
int fours = 0; // Number of double four rolls
int fives = 0; // Number of double five rolls
int sixes = 0; // Number of double six rolls
// TASK #1 Enter your code for the algorithm here Copyright © 2016 Pearson Education, Inc., Hoboken NJ
// Display the results
while(i<NUMBER)
{
die1Value=generator.nextInt(6);
die2Value=generator.nextInt(6);
if(die1Value==die2Value)
{
if(die1Value==1)
snakeEyes++;
else if(die1Value==2)
twos++;
else if(die1Value==3)
threes++;
else if(die1Value==4)
fours++;
else if(die1Value==5)
fives++;
else
sixes++;
}
i++;
count++;
}
System.out.println ("You rolled snake eyes " +
snakeEyes + " out of " +
count + " rolls.");
System.out.println ("You rolled double twos " +
twos + " out of " + count +
" rolls.");
System.out.println ("You rolled double threes " +
threes + " out of " + count +
" rolls.");
System.out.println ("You rolled double fours " +
fours + " out of " + count +
" rolls.");
System.out.println ("You rolled double fives " +
fives + " out of " + count +
" rolls.");
System.out.println ("You rolled double sixes " +
sixes + " out of " + count +
" rolls.");
}
}
-----------------------------------------------------------------
task2:-
-----------------------------------------------------------------
import java.util.Random;
public class DiceSimulation
{
public static void main(String[] args)
{
final int NUMBER = 10000;
int i=0;// Number of dice rolls
// A random number generator used in
// simulating the rolling of dice
Random generator = new Random();
int die1Value; // Value of the first die
int die2Value; // Value of the second die
int count = 0; // Total number of dice rolls
int snakeEyes = 0; // Number of snake eyes rolls
int twos = 0; // Number of double two rolls
int threes = 0; // Number of double three rolls
int fours = 0; // Number of double four rolls
int fives = 0; // Number of double five rolls
int sixes = 0; // Number of double six rolls
// TASK #1 Enter your code for the algorithm here Copyright © 2016 Pearson Education, Inc., Hoboken NJ
// Display the results
do
{
die1Value=generator.nextInt(6);
die2Value=generator.nextInt(6);
if(die1Value==die2Value)
{
if(die1Value==1)
snakeEyes++;
else if(die1Value==2)
twos++;
else if(die1Value==3)
threes++;
else if(die1Value==4)
fours++;
else if(die1Value==5)
fives++;
else
sixes++;
}
i++;
count++;
}while(i<NUMBER);
System.out.println ("You rolled snake eyes " +
snakeEyes + " out of " +
count + " rolls.");
System.out.println ("You rolled double twos " +
twos + " out of " + count +
" rolls.");
System.out.println ("You rolled double threes " +
threes + " out of " + count +
" rolls.");
System.out.println ("You rolled double fours " +
fours + " out of " + count +
" rolls.");
System.out.println ("You rolled double fives " +
fives + " out of " + count +
" rolls.");
System.out.println ("You rolled double sixes " +
sixes + " out of " + count +
" rolls.");
}
}
------------------------------for loop----------------
import java.util.Random;
public class DiceSimulation
{
public static void main(String[] args)
{
final int NUMBER = 10000;
int i=0;// Number of dice rolls
// A random number generator used in
// simulating the rolling of dice
Random generator = new Random();
int die1Value; // Value of the first die
int die2Value; // Value of the second die
int count = 0; // Total number of dice rolls
int snakeEyes = 0; // Number of snake eyes rolls
int twos = 0; // Number of double two rolls
int threes = 0; // Number of double three rolls
int fours = 0; // Number of double four rolls
int fives = 0; // Number of double five rolls
int sixes = 0; // Number of double six rolls
// TASK #1 Enter your code for the algorithm here Copyright © 2016 Pearson Education, Inc., Hoboken NJ
// Display the results
for(i=0;i<10000;i++)
{
die1Value=generator.nextInt(6);
die2Value=generator.nextInt(6);
if(die1Value==die2Value)
{
if(die1Value==1)
snakeEyes++;
else if(die1Value==2)
twos++;
else if(die1Value==3)
threes++;
else if(die1Value==4)
fours++;
else if(die1Value==5)
fives++;
else
sixes++;
}
count++;
}
System.out.println ("You rolled snake eyes " +
snakeEyes + " out of " +
count + " rolls.");
System.out.println ("You rolled double twos " +
twos + " out of " + count +
" rolls.");
System.out.println ("You rolled double threes " +
threes + " out of " + count +
" rolls.");
System.out.println ("You rolled double fours " +
fours + " out of " + count +
" rolls.");
System.out.println ("You rolled double fives " +
fives + " out of " + count +
" rolls.");
System.out.println ("You rolled double sixes " +
sixes + " out of " + count +
" rolls.");
}
}
------------------------writing results to file--------------------------
import java.io.BufferedWriter;
import java.io.FileWriter;
import java.io.IOException;
import java.util.Random;
/*
* To change this template, choose Tools | Templates
* and open the template in the editor.
*/
/**
*
* @author abhinay009
*/
public class WritingtoFile {
public static void main(String [] args) {
// The name of the file to open.
String fileName = "I://Results.txt";
final int NUMBER = 10000;
// This will reference one line at a time
String line = null;
int i=0;// Number of dice rolls
// A random number generator used in
// simulating the rolling of dice
Random generator = new Random();
int die1Value; // Value of the first die
int die2Value; // Value of the second die
int count = 0; // Total number of dice rolls
int snakeEyes = 0; // Number of snake eyes rolls
int twos = 0; // Number of double two rolls
int threes = 0; // Number of double three rolls
int fours = 0; // Number of double four rolls
int fives = 0; // Number of double five rolls
int sixes = 0; // Number of double six rolls
// TASK #1 Enter your code for the algorithm here Copyright © 2016 Pearson Education, Inc., Hoboken NJ
// Display the results
for(i=0;i<10000;i++)
{
die1Value=generator.nextInt(6);
die2Value=generator.nextInt(6);
if(die1Value==die2Value)
{
if(die1Value==1)
snakeEyes++;
else if(die1Value==2)
twos++;
else if(die1Value==3)
threes++;
else if(die1Value==4)
fours++;
else if(die1Value==5)
fives++;
else
sixes++;
}
count++;
}
try {
// Assume default encoding.
FileWriter fileWriter =
new FileWriter(fileName);
// Always wrap FileWriter in BufferedWriter.
BufferedWriter bufferedWriter =
new BufferedWriter(fileWriter);
// Note that write() does not automatically
// append a newline character.
bufferedWriter.write(""+snakeEyes);
bufferedWriter.newLine();
bufferedWriter.write(""+twos);
bufferedWriter.newLine();
bufferedWriter.write(""+threes);
bufferedWriter.newLine();
bufferedWriter.write(""+fours);
bufferedWriter.newLine();
bufferedWriter.write(""+fives);
bufferedWriter.newLine();
bufferedWriter.write(""+sixes);
// Always close files.
bufferedWriter.close();
}
catch(IOException ex) {
System.out.println(
"Error writing to file '"
+ fileName + "'");
// Or we could just do this:
// ex.printStackTrace();
}
}
}
----------------------------------------reading from file and caluclating mean and variance-----------------
import java.io.*;
public class Test {
public static void main(String [] args) {
// The name of the file to open.
String fileName = "I://Results.txt";
int sum=0;
// This will reference one line at a time
String line = null;
try {
// FileReader reads text files in the default encoding.
FileReader fileReader =
new FileReader(fileName);
// Always wrap FileReader in BufferedReader.
BufferedReader bufferedReader =
new BufferedReader(fileReader);
while((line = bufferedReader.readLine()) != null) {
sum=sum+Integer.parseInt(line);
}
int mean=sum/6,x;
System.out.println("Mean"+sum/6);
// Always close files.
bufferedReader.close();
FileReader fileReader2 =
new FileReader(fileName);
BufferedReader bufferedReader2 =
new BufferedReader(fileReader2);
sum=0;
while((line = bufferedReader2.readLine()) != null) {
x=mean-(Integer.parseInt(line));
sum=sum+x*x;
}
System.out.println("Variance"+sum/6);
bufferedReader2.close();
}
catch(FileNotFoundException ex) {
System.out.println(
"Unable to open file '" +
fileName + "'");
}
catch(IOException ex) {
System.out.println(
"Error reading file '"
+ fileName + "'");
// Or we could just do this:
// ex.printStackTrace();
}
}
}
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