Converting user input from integer to double

Question

I am trying to ask the user to enter 4 integer values followed by 4 double values. I keep getting the error "possible lossy conversion from double to int". I have tried different things but don't understand the simple conversion. Also.. might there be a better approach to this? Any advice for me is helpful. Eventually I am going to print out the values of these down the road...

import java.util.Scanner;

public class calculations {
    public static void main(String[] args) {

       Scanner keyboard = new Scanner(System.in);

       int[] intNumbers = new int[4];

       // Prompt user to enter 4 integer values here
       System.out.println("Enter 4 integer numbers below");

       // intNumbers only excepts 4 values with the for loop
       for (int i = 0; i < 4 && keyboard.hasNextInt(); i++) {
           intNumbers[i] = keyboard.nextInt();
       }

       double[] dblNumbers = new double[4];

       // Prompt users to enter 4 double values here
       System.out.println("Enter 4 double numbers below");

       // dblNumbers only excepts 4 values with the for loop
       for (double i = 0; i < 4 && keyboard.hasNextDouble(); i++) {
           dblNumbers[i] = keyboard.nextDouble();
       }

rgettman · Accepted Answer · 2015-01-07 23:28:56Z

3

You should not be using a double as an index into your array. Always use an int as an index. Change

for (double i = 0; i < 4 && keyboard.hasNextDouble(); i++) {
    dblNumbers[i] = keyboard.nextDouble();
}

to

//   vvv
for (int i = 0; i < 4 && keyboard.hasNextDouble(); i++) {
    dblNumbers[i] = keyboard.nextDouble();
}

answered Jan 7, 2015 at 23:28

rgettman

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3 Comments

Marcus Burkhart Over a year ago

So how should I go about this then because I need to prompt the user to input 4 integers and 4 doubles. Maybe an array is not the best idea?

Stack Exchange Broke The Law Over a year ago

@MarcusBurkhart do not confuse the indices and the values in the array. What do you think dblNumbers[i] means?

rgettman Over a year ago

@MarcusBurkhart Your approach was generally correct, but the index of the array is always an int, regardless of the type you need to store in the array. Note how the double is still be read from the Scanner.

Pang · Accepted Answer · 2015-01-08 00:52:12Z

0

You are using Double in your for-loop, which is not a good idea. Array indexes are always in int, so if you assign a double to it, it will give "possible loss conversion from double to int".

for (int i = 0; i < 4 && keyboard.hasNextDouble(); i++) {         
    dblNumbers[i] = keyboard.nextDouble();

edited Jan 8, 2015 at 0:52

Pang

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answered Jan 8, 2015 at 0:17

Amjad Islam Khan

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