I am a new coder. Working on an assignment. This is also my first post here so I apologize if it's a little sloppy.
I'm having some troubles with my if/else statements in Java...the "if" conditions seem to work okay. But my "else" conditions do not. Take a look at the code and the build results below.
Basically, I enter an ingredient. And then I put in the number of cups needed. And the number of calories the ingredient has per x cup. That all seems to work as long as I input what I want to for "successful" results.
But when I start to input values outside of my criteria, my application doesn't seem to care. If I input 0, I should get that output of "your response is invalid" or whatever it is I coded. But it just seems to skip over that entirely.
package recipe_collection_manager;
import java.util.Scanner;
public class Ingredient {
public static void main(String[] args) {
Scanner scnr = new Scanner(System.in);
//Initializes the variables
String nameOfIngredient = "";
int numberCups = 0;
int numberCaloriesPerCup = 0;
int totalCaloriesPerCup = 0;
double totalCalories = 0.0;
// Enter the name of the ingredient.
System.out.println("Please enter the name of the ingredient: ");
nameOfIngredient = scnr.next();
// Enter the number of cups needed for the ingredient.
// If Else statements used to establish if the number of cups is valid.
System.out.println("Please enter the number of cups of "
nameOfIngredient " we'll need. The number of cups must be between 1 and 100: ");
numberCups = scnr.nextInt();
if (numberCups >= 1 || numberCups <= 100) {
System.out.println("The number of cups is valid.");
} else if (numberCups <= 1 || numberCups >= 100) {
System.out.println("The number you have entered is invalid. Please try again.");
}
// Enter the number of calories used per cup.
// If Else statements are used to establish if the number of calories is valid.
System.out.println("Please enter the number of calories per cup: ");
numberCaloriesPerCup = scnr.nextInt();
if (numberCaloriesPerCup >= 1 || numberCaloriesPerCup <= 1000) {
System.out.println("The number of calories is valid.");
} else if (numberCaloriesPerCup <= 1 || numberCaloriesPerCup >= 1000) {
System.out.println("The number you have entered is invalid. Please try again.");
}
// Calculation for totalCalories based on numberCups and numberCaloriesPerCup
if (numberCups > 0 && numberCaloriesPerCup > 0) {
totalCalories = numberCups * numberCaloriesPerCup;
}
System.out.println(nameOfIngredient " uses " numberCups
" cups and has " totalCalories " calories.");
}
}
CodePudding user response：
Problem was in line:
if (numberCups >= 1 || numberCups <= 100) {
...
}
When you entered 0, program checked if 0 is greater or equal to 1, and that was false but you had also "or" condition ( || ), and in that condition you were checking if 0 <= 100 and because that is true, false || true gives true and that's why your if statement was correct. You needed to use "and" ( && ) instead of "or". There was flaw in your logic.
Test code below, it should work now:
package recipe_collection_manager;
import java.util.Scanner;
public class Ingredient {
public static void main(String[] args) {
Scanner scnr = new Scanner(System.in);
//Initializes the variables
String nameOfIngredient = "";
int numberCups = 0;
int numberCaloriesPerCup = 0;
int totalCaloriesPerCup = 0;
double totalCalories = 0.0;
// Enter the name of the ingredient.
System.out.println("Please enter the name of the ingredient: ");
nameOfIngredient = scnr.next();
// Enter the number of cups needed for the ingredient.
// If Else statements used to establish if the number of cups is valid.
System.out.println("Please enter the number of cups of "
nameOfIngredient " we'll need. The number of cups must be between 1 and 100: ");
numberCups = scnr.nextInt();
if (numberCups >= 1 && numberCups <= 100) {
System.out.println("The number of cups is valid.");
} else if (numberCups <= 1 || numberCups >= 100) {
System.out.println("The number you have entered is invalid. Please try again.");
}
// Enter the number of calories used per cup.
// If Else statements are used to establish if the number of calories is valid.
System.out.println("Please enter the number of calories per cup: ");
numberCaloriesPerCup = scnr.nextInt();
if (numberCaloriesPerCup >= 1 || numberCaloriesPerCup <= 1000) {
System.out.println("The number of calories is valid.");
} else if (numberCaloriesPerCup <= 1 || numberCaloriesPerCup >= 1000) {
System.out.println("The number you have entered is invalid. Please try again.");
}
// Calculation for totalCalories based on numberCups and numberCaloriesPerCup
if (numberCups > 0 && numberCaloriesPerCup > 0) {
totalCalories = numberCups * numberCaloriesPerCup;
}
System.out.println(nameOfIngredient " uses " numberCups
" cups and has " totalCalories " calories.");
}
}
CodePudding user response：
Just to clarify. The following statement
if(numberCups >= 1 || numberCups <= 100) {
...
}
Is true any number of cups. Any number of cups >= 1 will be caught by the first condition. Any number of cups <= 0 will be caught by the second condition since in that case they will all be less than 100. With a logical || only one condition is required to be true for the statement to be true.
In fact,
if(numberOfCups is >= A || numberOfCups <= B) {
...
}
will always be true as long as B >= A-1.
CodePudding user response：
if (numberCups >= 1 || numberCups <= 100) {
...
}
So, here you see, 0 is not bigger than 1, but it is smaller than 100. See the problem now? So, use && in place for || if you want to code more than 1 but less than 100.