Using loops to Ensure Correct Variable Type from User Input - Programmers Heaven

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Using loops to Ensure Correct Variable Type from User Input

First off, sorry if my title is a little misleading.

What I mean to ask, is if I am asking a user to input something, say a dollar amount, and they enter it in type double when I want type int, it'll either mess my program up or result in a run time error.

How would I use loops to ensure that this doesn't happen and instead gives the user an error message and asks them to re-input the value? Or is there another way to do it that I do not know of?

I am a very basic beginner taking classes at college when I ran into this problem. I figure I would ask the forums rather then my teacher because I know she doesn't want me to jump ahead of the curriculum too much.

Thanks for all the help!

p.s Here is the program I built where I was thinking I could implement this idea.
Scanner scan = new Scanner(;

int tens, fives, ones;
double money, quarters, dimes, nickels, pennies;

System.out.print("Enter the amount of money you have and I'll tell you how much change you can get
money = scan.nextDouble();

tens = (int)money/10;
money = money%10;
fives = (int)money/5;
money = money%5;
ones = (int)money/1;
money = money%1;
quarters = money/0.25;
money = money%0.25;
dimes = money/0.10;
money = money%0.10;
nickels = money/0.05;
money = money%0.05;
pennies = money/0.01;

System.out.println(tens + " ten dollar bills");
System.out.println(fives + " five dollar bills");
System.out.println(ones + " one dollar bills");
System.out.println((int)quarters + " quarters");
System.out.println((int)dimes + " dimes");
System.out.println((int)nickels + " nickels");
System.out.println((int)pennies + " pennies");
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