Error Trying to Create Array of Double Variable Type

Question

I'm trying to create a program which takes values that are doubles from the user and stores them in arrays before dividing them and rounding the answers. However I keep receiving errors trying to create double arrays.

 double n = sc.nextDouble();

    double a[] = new double[n];
    double b[] = new double[n];
    double roundedValues[] = new double[n];

    for (double i = 0; i < a.length; i++) {
        System.out.println("Please enter the values you would like to divide as pairs of two numbers: ");
        // Read pair and store it inside i-th position of a and b arrays 
        System.out.println("Enter first number: ");
        a[i] = sc.nextDouble();
        System.out.println("Enter second number you would like to divide by: ");
        b[i] = sc.nextDouble();
        roundedValues[i] = Math.round(a[i] / b[i]);
    }

The error I'm getting where I've declared the arrays says:

incompatible types: possible lossy conversion from double to int

What does an array with a double number of elements mean? I've never seen an array with 3.2734 elements. — Eran
– Eran, Commented Jul 9, 2017 at 20:40
I've changed the control variable in the loop to int and that has solved that issue but i'm still getting the same error on the lines where I have declared the arrays. Can you help me understand why? I'd like to store values that are decimal numbers within the arrays I have created. Thanks — Spartan123
– Spartan123, Commented Jul 9, 2017 at 20:45
See Eran's comment. You're still creating a[] and b[] with a "double" number of elements. Anything in the the brackets needs to be an int. — Mike
– Mike, Commented Jul 9, 2017 at 20:47
OK. I'd like to store values that are decimal numbers within the arrays I have created, hence why I tried initialising the array as a double. I think I understand where I was going wrong, I thought that the int was responsible for the type of values that could be stored within the array. Is there a way I can store values that are of the type double within the array? — Spartan123
– Spartan123, Commented Jul 9, 2017 at 20:52

Nate · Accepted Answer · 2017-07-09 23:03:19Z

Firstly, variable n, defined as double n = sc.nextDouble(); is a double. You can't make an array whose length is a double because then you might end up with half an element. Imagine an array 4.5 elements long!

Define n like one of these instead:

int n = sc.nextInt()
or
int n = (int)sc.nextDouble();

Secondly, i is also a double! Define it like this:

for (int i = 0; i < a.length; i++) {

That way the compiler knows that i is an integer and doesn't have to worry about needing to retreive an element at a double index, like the 4.2th element! (which doesn't, and shouldn't exist)

Heres the fixed code:
int n = sc.nextInt();

double a[] = new double[n];
double b[] = new double[n];
double roundedValues[] = new double[n];

for (int i = 0; i < a.length; i++) {
    System.out.println("Please enter the values you would like to divide as pairs of two numbers: ");
    // Read pair and store it inside i-th position of a and b arrays 
    System.out.println("Enter first number: ");
    a[i] = sc.nextDouble();
    System.out.println("Enter second number you would like to divide by: ");
    b[i] = sc.nextDouble();
    roundedValues[i] = Math.round(a[i] / b[i]);
}

fg78nc · Accepted Answer · 2017-07-09 20:50:50Z

1

a[i] and b[i] expect int type, but you supply double to it
Should be 
 for (int i = 0; i < a.length; i++) {

and

 double n = sc.nextDouble();
   should be changed to:
 int n = sc.nextInt();

edited Jul 9, 2017 at 20:50

answered Jul 9, 2017 at 20:42

fg78nc

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3 Comments

Araymer Over a year ago

The exception is coming from the fact that OP is using a double for n, and trying to declare that as the number of elements int he array declarations.

Spartan123 Over a year ago

I've changed the control variable in the loop to int and that has solved that issue but i'm still getting the same error on the lines where I have declared the arrays. Can you help me understand why? I'd like to store values that are decimal numbers within the arrays I have created. Thanks

Araymer Over a year ago

Change your n variable to an int and use nextInt() instead of nextDouble()

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