Units conversion program

[minterman]

1. the program needs to convert btu to jules
2. Convert calories to joules
3. Convert joules to joules
4 exit the program.
if the user type anything other than 1-4 the program should print a error message.

here is my code.

import java.util.Scanner;
 
public class joules {
    public static void main (String [] args) {
        final double BTUs = 1056;
        final double calories = 4.184;
        final double joule = 1;
        Scanner stdin = new Scanner(System.in);
        System.out.println ("1. Convert BTUs to joules");
        System.out.println ("2. Convert Calories to joules");
        System.out.println ("3. Convert joules to joules");
        System.out.println ("4. Exit program");
        int choice = stdin.nextInt();
        while (choice != 4)
            if (choice < 1 || choice > 3)
            //converting to joules using constants
            if (choice = 1) {
            double amount = stdin.nextDouble();
            double joules = amount * BTUs;
        System.out.println (amount + " BTUs is " + joules  "joules");
                }
        if (choice = 1) {double amount = stdin.nextDouble();
            double joules = amount * calories;
        System.out.println (amount + " Calories is " + joules + "joules");
                }
            if (choice = 1) {
            double amount = stdin.nextDouble();
            double joules = amount * joule;
            System.out.println (amount + " joules is " + joules + "joules");
                }
            //statement for wrong entries
            else {
        System.out.println ("That is not a valid entry.  Try again");
            }
 

[horace1]

what is your problem?

[DeMan]

You do, of course realise that you only ever check for option 1 (and doesn't java require ==)

[minterman]

what is your problem?

I started writing the code to convert btu to joules. This code is not working for me

[r035198x]

1. the program needs to convert btu to jules
2. Convert calories to joules
3. Convert joules to joules
4 exit the program.
if the user type anything other than 1-4 the program should print a error message.

here is my code.

import java.util.Scanner;
 
public class joules {
    public static void main (String [] args) {
        final double BTUs = 1056;
        final double calories = 4.184;
        final double joule = 1;
        Scanner stdin = new Scanner(System.in);
        System.out.println ("1. Convert BTUs to joules");
        System.out.println ("2. Convert Calories to joules");
        System.out.println ("3. Convert joules to joules");
        System.out.println ("4. Exit program");
        int choice = stdin.nextInt();
        while (choice != 4)
            if (choice < 1 || choice > 3)
            //converting to joules using constants
            if (choice = 1) {
            double amount = stdin.nextDouble();
            double joules = amount * BTUs;
        System.out.println (amount + " BTUs is " + joules "joules");
                }
        if (choice = 1) {double amount = stdin.nextDouble();
            double joules = amount * calories;
        System.out.println (amount + " Calories is " + joules + "joules");
                }
            if (choice = 1) {
            double amount = stdin.nextDouble();
            double joules = amount * joule;
            System.out.println (amount + " joules is " + joules + "joules");
                }
            //statement for wrong entries
            else {
        System.out.println ("That is not a valid entry. Try again");
            }
 

You should be using a switch for this.

 int choice = stdin.nextInt(); 
switch(choice) {
       case 1: {
 
               break;
        }
        case 2: {
 
               break;
        }
        .
        .
        .
       default : {
        //wrong input 
 
       }
 

What error did you get?

[horace1]

your logic in the following statement where you test if choice is between 1 and 3 inclusive is incorrect

        while (choice != 4)
            if (choice < 1 || choice > 3)
 

you test if choice is less than 1 or greater than 3
you need to test if choice is greater than or equal to 1 AND less than or equal to 3, e.g.

                while (choice != 4)
                        if (choice >= 1 && choice <= 3)
 

also as DeMan indicated statements such as

            if (choice = 1) {
 

should use ==

            if (choice == 1) {
 

however, as indicated by r035198x, it would be better to use a switch statement

[minterman]

1. the program needs to convert btu to jules
2. Convert calories to joules
3. Convert joules to joules
4 exit the program.
if the user type anything other than 1-4 the program should print a error message.


I can not get this code to execute Please hellp
here is my code.
Code:

import java.util.*;
public class Project_2 {
// main(): application entry point
public static void main (String [] args) {
final double BTUs =1056;
final double calories =4.184;
final double joule =1;
int choice;
// set up input stream
Scanner stdin = new Scanner(System. in);
System.out.prin tln ("1. Convert BTUs to Joules");
System.out.prin tln ("2. Convert Calories to Joules");
System.out.prin tln ("3. Convert Joules to Joules");
System.out.prin tln ("4. Exit program");
int choice=stdin.ne xtInt();
//converting BTUS to Joules
switch (choice){
case 1:
double amount = stdin.nextDoubl e();
double joules = amount * BTUs;
System.out.prin tln (amount + "BTUs is " + joules + "joules");
break;
// converting Calories to Joules
case 2:
double joules = amount * calories;
System.out.prin tln (amount + "Calories is " + joules + "joules");
break;
// converting Joules to Joules
case 3:
double joules = amount * joule;
System.out.prin tln (amount + "joules is " + joules + "joules");
break;
// exit program
case 4:
System.exit(0)
break;
default:
System.out.prin tln ("You have entered an incorrect number, Please try again.");
}
}
}

[r035198x]

1. the program needs to convert btu to jules
2. Convert calories to joules
3. Convert joules to joules
4 exit the program.
if the user type anything other than 1-4 the program should print a error message.


I can not get this code to execute Please hellp
here is my code.
Code:

import java.util.*;
public class Project_2 {
// main(): application entry point
public static void main (String [] args) {
final double BTUs =1056;
final double calories =4.184;
final double joule =1;
int choice;
// set up input stream
Scanner stdin = new Scanner(System. in);
System.out.prin tln ("1. Convert BTUs to Joules");
System.out.prin tln ("2. Convert Calories to Joules");
System.out.prin tln ("3. Convert Joules to Joules");
System.out.prin tln ("4. Exit program");
int choice=stdin.ne xtInt();
//converting BTUS to Joules
switch (choice){
case 1:
double amount = stdin.nextDoubl e();
double joules = amount * BTUs;
System.out.prin tln (amount + "BTUs is " + joules + "joules");
break;
// converting Calories to Joules
case 2:
double joules = amount * calories;
System.out.prin tln (amount + "Calories is " + joules + "joules");
break;
// converting Joules to Joules
case 3:
double joules = amount * joule;
System.out.prin tln (amount + "joules is " + joules + "joules");
break;
// exit program
case 4:
System.exit(0)
break;
default:
System.out.prin tln ("You have entered an incorrect number, Please try again.");
}
}
}

 
import java.util.*;
public class Project_2 {
// main(): application entry point
 public static void main (String [] args) {
  final double BTUs =1056;
  final double calories =4.184;
  final double joule =1;
  // set up input stream
  Scanner stdin = new Scanner(System.in);
  System.out.println ("1. Convert BTUs to Joules");
  System.out.println ("2. Convert Calories to Joules");
  System.out.println ("3. Convert Joules to Joules");
  System.out.println ("4. Exit program");
  int choice=stdin.nextInt();
  //converting BTUS to Joules
  switch (choice){
   case 1: {
    System.out.println ("Enter the BTUs");
    double amount = stdin.nextDouble();
    double joules = amount * BTUs;
    System.out.println (amount + "BTUs is " + joules + "joules");
    break;
   }
   // converting Calories to Joules
   case 2: {
    System.out.println ("Enter the Calories");
    double amount = stdin.nextDouble();
    double joules = amount * calories;
    System.out.println (amount + "Calories is " + joules + "joules");
    break;
   }
   // converting Joules to Joules
   case 3: {
    System.out.println ("Enter the Joules");
    double amount = stdin.nextDouble();
    double joules = amount * joule;
    System.out.println (amount + "joules is " + joules + "joules");
    break;
   }
   // exit program
   case 4: {
    System.exit(0);
   }
   default: {
    System.out.println ("You have entered an incorrect number, Please try again.");
   }
  }
 }
}
 
 

You were missing declarations for amount in the other case statements. Now make it possible to make many conversions before the program exits. Currently you can do only one conversion and then the program exits. You will need to use a while loop.

[minterman]

Thanks a Lot this got me on the right track. I added a while (true){
to get the program to keep looping but I want to make it pause after each calulations. How do I do that.

Thanks
Minterman

[r035198x]

Thanks a Lot this got me on the right track. I added a while (true){
to get the program to keep looping but I want to make it pause after each calulations. How do I do that.

Thanks
Minterman

How do you want it to pause? Pause until the user does something or pause for a specific period of time?