Java DecimalFormat-使用整数

Question

I have a currency in pennies, as an integer (ex: 1234 ). I need the output to be: $12.34 . We are not allowed to use doubles or floats on this assignment, only Integers.

Here is what I have:

totalChange = 1234;
DecimalFormat ourFormat = new DecimalFormat("$#,###.00");
String totalString = ourFormat.format(totalChange);
System.out.println("Your change of " + totalString + " is as follows:");

I would assume that the DecimalFormat would go from right to left, assigning 34 to be after the decimal point, and the 12 should be placed before.

I'm getting an output of Your change of $1234.00 is as follows:

Answer 1

Format will not artificially introduce decimal places not present in the input.

You could try converting to dollars and cents first, then combining the two with '.'

int dollars = totalChange / 100;
int cents = totalChange % 100;

Hint (Based on comment from @DanielFischer)

Cents can be 1 or 2 digits, but you probably want to output them always as 2 digits.

Answer 2

This problem is probably trying to teach you about integer division and modulus.

When you divide integers, the remainder is completely discarded, so you need to use the modulo operator if you want that information. The modulo operator (%) gives you only the remainder from division. For example 5 / 3 = 1 and 5 % 3 = 2.

These operations lend themselves very nicely to your problem.

Say I want to figure out how many nickels and pennies I need to make exact change for some amount.

int totalChange = 27; //I have 27¢
int nickels = totalChange / 5; //This gives 5 and discards the remainder
int pennies = totalChange % 5; //This gives 2, the remainder from your previous division

Answer 3

For formatting, use Formatter.format(), giving it the dollars and cents as arguments and formatting it with the leading $ and exactly 2 digits for the cents (as suggested by someone above). Since it's homework, i won't give away how to do this, but the javadocs should help:

http://docs.oracle.com/javase/1.5.0/docs/api/java/util/Formatter.html#syntax

Answer 4

I don't know if this violates your rules (which sound really weird, but hay). You could try

int totalChange = 1234;
DecimalFormat ourFormat = new DecimalFormat("$#,###.00");
String totalString = ourFormat.format(totalChange / 100f);
System.out.println("Your change of " + totalString + " is as follows:");

Otherwise, I think you'd need to provide your own formatter.