Question

Java Assignment

Calculator with methods. My code appears below what I need to correct.

What I need to correct is

if the user attempts to divide a number by 0, the divide() method is supposed to return Double.NaN, but your divide() method doesn't do this. Instead it does this:

    public static double divide(double operand1, double operand2) {
        return operand1 / operand2;
    }

The random method is supposed to return a double within a lower limit and an upper limit, not an int type cast to a double.

public static double random(double x, double y) {
        Random generator = new Random();
        return generator.nextInt((int)(y - x) + 1) + x;
    }

Code Starts Here.

import java.util.Random;

import java.util.Scanner;

public class CalculatorWithMethods {

static Scanner input = new Scanner(System.in);

boolean mainloop = true;

public static void main(String[] args) {

double res;

int count = 0;

while(true) {

int choice = (int) getMenuOption();

switch (choice) {

case 1:

{

//Method for getting operands.

double operand1 = getOperand("What is the first number?");

double operand2 = getOperand("What is the second number?");

res = add(operand1, operand2);

System.out.println(operand1 + " + " + operand2 + " = " + res);

break;

}

case 2:

{

double operand1 = getOperand("What is the first number?");

double operand2 = getOperand("What is the second number?");

res = subtract(operand1, operand2);

System.out.println(operand1 + " - " + operand2 + " = " + res);

break;

}

case 3:

{

double operand1 = getOperand("What is the first number?");

double operand2 = getOperand("What is the second number?");

res = multiply(operand1, operand2);

System.out.println(operand1 + " * " + operand2 + " = " + res);

break;

}

case 4:

{

double operand1 = getOperand("What is the first number?");

double operand2 = getOperand("What is the second number?");

if (operand2 == 0) {

System.out.println("Double.NaN");

} else {

operand1 = getOperand("What is the first number?");

operand2 = getOperand("What is the second number?");

res = divide(operand1, operand2);

System.out.println(operand1 + " / " + operand2 + " = " + res);

}

break;

}

case 5:

{

double operand1 = getOperand("What is the lower limit ?");

double operand2 = getOperand("What is the upper limit ?");

res = random(operand1, operand2);

System.out.println("The Random Number is :" + res);

break;

}

default: {

count++;

System.out.println("** Invalid Choice **");

}

}

if(count == 3){

break;

}

}

}

//Addition.

public static double add(double operand1, double operand2) {

return operand1 + operand2;

}

//Subtraction.

public static double subtract(double operand1, double operand2) {

return operand1 - operand2;

}

//Multiplication

public static double multiply(double operand1, double operand2) {

return operand1 * operand2;

}

//Division

public static double divide(double operand1, double operand2) {

return operand1 / operand2;

}

//Random number

public static double random(double x, double y) {

Random generator = new Random();

return generator.nextInt((int)(y - x) + 1) + x;

}

//Getting the operands.

public static double getOperand(String str) {

System.out.print(str);

double num = input.nextDouble();

return num;

}

//Display menu

public static double getMenuOption() {

double choice;

System.out.println("\nMenu\n1. Add\n2. Subtract\n3. Multiply\n4. Divide\n5. Generate Random Number\n6. Quit");

System.out.println("What would you like to do?");

choice = input.nextInt();

return choice;

}

}

Answer 1

import java.util.Scanner;

public class CalculatorWithMethods {

static Scanner input = new Scanner(System.in);

boolean mainloop = true;

public static void main(String[] args) {

double res;

int count = 0;

while (true) {

int choice = (int) getMenuOption();

switch (choice) {

case 1:

{

// Method for getting operands.

double operand1 = getOperand("What is the first number?");

double operand2 = getOperand("What is the second number?");

res = add(operand1, operand2);

System.out.println(operand1 + " + " + operand2 + " = " + res);

break;

}

case 2:

{

double operand1 = getOperand("What is the first number?");

double operand2 = getOperand("What is the second number?");

res = subtract(operand1, operand2);

System.out.println(operand1 + " - " + operand2 + " = " + res);

break;

}

case 3:

{

double operand1 = getOperand("What is the first number?");

double operand2 = getOperand("What is the second number?");

res = multiply(operand1, operand2);

System.out.println(operand1 + " * " + operand2 + " = " + res);

break;

}

case 4:

{

double operand1 = getOperand("What is the first number?");

double operand2 = getOperand("What is the second number?");

if (operand2 == 0) {

System.out.println("Double.NaN");

} else {

operand1 = getOperand("What is the first number?");

operand2 = getOperand("What is the second number?");

res = divide(operand1, operand2);

System.out.println(operand1 + " / " + operand2 + " = " + res);

}

break;

}

case 5:

{

double operand1 = getOperand("What is the lower limit ?");

double operand2 = getOperand("What is the upper limit ?");

res = random(operand1, operand2);

System.out.println("The Random Number is :" + res);

break;

}

default: {

count++;

System.out.println("** Invalid Choice **");

}

}

if (count == 3) {

break;

}

}

}

// Addition.

public static double add(double operand1, double operand2) {

return operand1 + operand2;

}

// Subtraction.

public static double subtract(double operand1, double operand2) {

return operand1 - operand2;

}

// Multiplication

public static double multiply(double operand1, double operand2) {

return operand1 * operand2;

}

// Division

public static double divide(double operand1, double operand2) {

// if operand2 is 0 than return Nan

if(operand2==0)

return Double.NaN;

return operand1 / operand2;

}

// Random number

public static double random(double x, double y) {

// using random from math class to generate within range

return Math.random() * ((y - x) + 1)+ x;

}

// Getting the operands.

public static double getOperand(String str) {

System.out.print(str);

double num = input.nextDouble();

return num;

}

// Display menu

public static double getMenuOption() {

double choice;

System.out.println("\nMenu\n1. Add\n2. Subtract\n3. Multiply\n4. Divide\n5. Generate Random Number\n6. Quit");

System.out.println("What would you like to do?");

choice = input.nextInt();

return choice;

}

}