Java: Trying to get the percentage of integers, how to round up?

Question

I have two integer values, x and total. I am trying to find the percentage of x in total as an integer. This is how I am doing it right now:

percentage = (int)((x*100)/total);

The percentage must be an integer. When I do this it always rounds the decimal point down. Is there a simple way to calculate the percentage as an integer so it rounds up if the decimal is .5 or higher?

Solution 1

Use Math.round(x * 100.0/total). But note that this returns a long, so a simple cast to int will be required.

I put 100.0 to force it to use floating point arithmetic prior to the rounding.

Solution 2

(int)Math.round(100.0 / total * x);

should work.

Solution 3

Just use Math.round(100.0 / total * x);

Solution 4

Use the standard math library in Java.

percentage = Math.round(*your expression here*);

Solution 5

Why not use Math.round((x*100)/total);

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Comments

[Dharini Chandrasekaran]

There is an overloaded method which returns int. So a cast isn't absolutely necessary.

[joshuahealy]

@DhariniChandrasekaran I believe it returns an int if you pass in a float? The way I've written it it will pass in a double and return a long.

[joshuahealy]

@Churk actually I edited my answer because x, 100 and total were all ints so the arithmetic would've all been integers and the call to round would've been a waste of time. I changed to 100.0 to make it use floating point arithmetic and then added an explanation for it.

[joshuahealy]

@Churk perhaps you should take a look at the revisions of my answer before making silly false accusations.

[joshuahealy]

This answer doesn't solve the problem as x and total are both integers. The expression will be evaluated using integer arithmetic and will be "rounded" down before being passed into the round function.

[Stephane Delcroix]

It only partially answer the question. could you elaborate to form a complete answer ?

[Andrew Barber]

It's also not correct; you may want to read the question more carefully, and check out the many existing answers which correctly answer it.