Question

write a program that first asks the user to enter three real numbers using GUI input. Print the sum if all three numbers are positive, print the product of the two positive numbers if only one is negative - use a nested if. Then, ask the user to enter two real numbers from the console. If both numbers are negative, print the quotient.

Answer 1

Answer:

Here is the complete program:

import javax.swing.JOptionPane;  //to use GUI in JAVA application

import java.util.Scanner;  //to take input from user at console

public class Main {

public static void main(String[] args) {  //start of main function body

 String num1, num2,num3;  //declare three variables to store strings of numbers for input dialog

 double number1, number2, number3, sum,product; //declare three double type variables to hold the real numbers  

 num1 = JOptionPane.showInputDialog("num1");  //shows a dialog box prompting user to enter value of first number i.e. num1

 number1 = Double.parseDouble(num1);  //scans and reads the value of first input number i.e. number1    

 num2 = JOptionPane.showInputDialog("num2");  //shows a dialog box prompting user to enter value of second number i.e. num2

 number2 = Double.parseDouble(num2);   //reads number2  

               num3 = JOptionPane.showInputDialog("num3");  //shows a dialog box prompting user to enter value of third number i.e. num3

 number3 = Double.parseDouble(num3);   //reads number3  

   if(number1>0&& number2>0 && number3>0){  //checks if all three numbers are positive

   sum = number1 + number2+ number3;  //displays the sum by adding all three positive numbers

   JOptionPane.showMessageDialog(null, "the sum is : " + sum , "Results", JOptionPane.PLAIN_MESSAGE );      }   // displays the result of sum in a message dialog box

 

    if(number1<0 && number2>0 && number3>0)      {  //checks if number2 and number3 are positive

   product = number2*number3;  //computes product

   JOptionPane.showMessageDialog(null, "the product is : " + product , "Results", JOptionPane.PLAIN_MESSAGE );      }  //displays the result

   else if (number2<0&&number1>0&&number3>0){  //checks if number1 and number3 are positive

    product = number1*number3;  //computes product

JOptionPane.showMessageDialog(null, "the product is : " + product , "Results", JOptionPane.PLAIN_MESSAGE );      }  //displays the result

   else if (number3<0 && number1>0 && number2>0)     {  //checks if number1 and number2 are positive

     product = number1*number2;  //computes product of 2 positive numbers

     JOptionPane.showMessageDialog(null, "the product is : " + product , "Results", JOptionPane.PLAIN_MESSAGE );      }  //displays the result

   else     {  /.if all the numbers are positive.

/*However this part is optional. You can just use else part for above else if statement and exclude this else part. In this way the product of all three positive numbers is not computed and product is only computed when only two numbers of the three are positive */

     product = number1*number2*number3;  //computes product of all three positive numbers

     JOptionPane.showMessageDialog(null, "the product is : " + product , "Results", JOptionPane.PLAIN_MESSAGE );      }   //displays the result

Scanner scan = new Scanner(System.in);  //creates a Scanner class object

double value1 , value2, quotient;  //declares variables to hold the values of two real numbers and the result of division of the two real numbers is stored in quotient variable

System.out.println("Enter the first real number: ");  //prompts user to enter the value of first real number from the console

value1 = scan.nextDouble();  //reads the first number from user

System.out.println("Enter the second real number : ");  //prompts user to enter the value of second real number from the console

value2 = scan.nextDouble();  //reads the second number from user

if(value1<0&&value2<0)  {  //checks if both the numbers are negative

quotient = value1/value2;  //compute the quotient

JOptionPane.showMessageDialog(null, "the quotient is : " + quotient , "Results", JOptionPane.PLAIN_MESSAGE );    }  //displays result

 else  //if both numbers are not negative

JOptionPane.showMessageDialog(null, "Both numbers are not negative" );   //displays this message in a dialog box

  }  }

Explanation:

In the above given code if you want to display the outputs in console then alter the following statements as follows:

   if(number1>0&& number2>0 && number3>0){

   sum = number1 + number2+ number3;

  System.out.println("the sum is :  " + sum); }      

 

    if(number1<0 && number2>0 && number3>0)      {

    product = number2*number3;

      System.out.println("the product is :  " + product); }          

   else if (number2<0&&number1>0&&number3>0){

          product = number1*number3;

System.out.println("the product is :  " + product);      }

   else if (number3<0 && number1>0 && number2>0)     {

     product = number1*number2;

     System.out.println("the product is :  " + product);     }

   else     {

     product = number1*number2*number3;

      System.out.println("the product is :  " + product);      }

Scanner scan = new Scanner(System.in);

double value1 , value2, quotient;

System.out.println("Enter the first real number: ");

value1 = scan.nextDouble();

System.out.println("Enter the second real number : ");

value2 = scan.nextDouble();

if(value1<0&&value2<0)  {

quotient = value1/value2;

 System.out.println("the quotient is :  " + quotient);   }

 else  

System.out.println("Both numbers are not negative");

Notice that all the JOptionPane.showMessageDialog statement are changed with System.out.println which prints the results on the console.