How to ask the user for an input that effects another variable

Question

I need to create a way for the user to enter the weather (snowy, rainy, or sunny) and after they do this it effects the MPG (Miles Per Gallon) of the car. Snowy minuses 4, rainy minuses 2 and sunny has no effect. The hint I had was to use in.equals but I know my code is far off. So my question is how do I ask the user for a input that effects another variable with three possible answers?

 import java.util.Scanner;

public class AdvancedTripCalc {

    public static void main(String[] args) {
        // New Trip Calc.
        String firstname;
        int mpg;
        int miles;
        double price;
        double totalcost;

        Scanner in = new Scanner(System.in);
        System.out.println("Please enter your First Name");
        firstname = in.nextLine();
        System.out.println("Please enter the MPG of your car");
mpg = in.nextInt();
boolean city;
System.out.println("Enter true if trip is in the city false if the trip is on the highway");
city = in.nextBoolean();
if (city){
    mpg = mpg - 2;
}
else { 
    mpg = mpg + 5;
}
boolean weather;
double snowy = 0;
double rainy = 0;
double sunny = 0;
System.out.println("What is the weather like?");
weather = in.equals(snowy);
{
    mpg = mpg - 4;
}
weather = in.equals(rainy);{
    mpg = mpg - 1;
}
weather = in.equals(sunny);{
    mpg = mpg;
}
System.out.println("Please enter the Miles to be traveled");
miles = in.nextInt();
System.out.println("Please enter the price per gallon of gas");
price = in.nextDouble();

totalcost = miles * price / mpg;
System.out.println("Your name is " +firstname);
System.out.println("Your MPG is " +mpg);
System.out.println("Your miles to be traveled is " +miles);
System.out.println("Your price per gallon of gas is " +price);
System.out.println("Your total cost is " +totalcost);

    }

}

This is what I have so far.

score 0 · Answer 1 · answered May 26 '16 at 12:49

Comparing Strings in java is done with a.equals(b) if a and b are Strings.

a == b would test if a and b are the same Object. So what you need to do is: Read weather as a String (String weather = in.readLine() for example) and then you can compare it with:

if(weather.equals("snowy"){..}

else if(weather.equals("rainy"){..}

and so on

score 0 · Answer 2 · answered May 26 '16 at 12:51

What you can do is take the user's input and compare it using a case statement (or even an if statement) like so:

System.out.println("What is the weather like?");
Scanner read = new Scanner(System.in);
string weather = read.next()
if (weather.equals("snowy")){
    mpg -= 4;}
else if (weather.equals("rainy")){
    mpg -= 2;}

score -1 · Answer 3 · edited May 23 '17 at 12:07

There is a pretty good example here Reading in from System.in - Java which I dont have time to write out for you. But essentially you need to create a Scanner for system.in this will block the application at that point and wait for some input on System in, before continuing. It is general a good idea to do a System.out.print before this so that the user knows they need to enter something.

Idos · Accepted Answer · 2016-05-26T12:51:58.853

-1

You can just use if statements after reading the user input with next() on the Scanner object you have (in):

String weather = in.next();
if (weather.equals("snowy"))
    mpg -= 4;
else if (weather.equals("rainy"))
    mpg -= 1;
...
else System.out.println("Wrong input");

edited May 26 '16 at 12:51

answered May 26 '16 at 12:46

Idos

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Downvoter please explain – Idos May 26 '16 at 12:48
Well it was wrong as you know. But fixed now so will change. – weston May 26 '16 at 12:50
You are right but give a man a chance to edit since it was just an oversight ;) – Idos May 26 '16 at 12:51
Sure and I would have explained but you deleted it before I could. – weston May 26 '16 at 13:01
1

I used this method and it worked! Thank you so much for the help, I know this is probably extremely basic. – Slowwork May 26 '16 at 13:02

score -1 · Answer 5 · answered May 26 '16 at 12:50

-1

You can't use in.equals, but you can read a string and then to .equals:

String weather = in.next();
if("sunny".equals(weather)) {
    mpg = mpg - 4;
} else if("rainy".equals(weather)) {
    mpg = mpg - 1;
}

answered May 26 '16 at 12:50

weston

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How to ask the user for an input that effects another variable

5 Answers5