Java Round up Any Number

Question

I can't seem to find the answer I'm looking for regarding a simple question: how do I round up any number to the nearest int?

For example, whenever the number is 0.2, 0.7, 0.2222, 0.4324, 0.99999 I would want the outcome to be 1.

So far I have

int b = (int) Math.ceil(a / 100);

It doesn't seem to be doing the job, though.

yea ur right a is an int... thanks for pointing that out. 100.0 sorted it for me. — Stevanicus, Dec 27 '10 at 18:05
I'm guessing what he wants is a/100 rounded up, but yeah, the question could use some clarification. — Jay, Dec 27 '10 at 18:33
**NOTE: At [this](http://stackoverflow.com/questions/7139382/java-rounding-up-to-an-int-using-math-ceil/21830188#21830188) question better answers are provided.** — martijnn2008, May 30 '15 at 13:04

score 341 · Accepted Answer · answered Dec 27 '10 at 18:02

341

Math.ceil() is the correct function to call. I'm guessing a is an int, which would make a / 100 perform integer arithmetic. Try Math.ceil(a / 100.0) instead.

int a = 142;
System.out.println(a / 100);
System.out.println(Math.ceil(a / 100));
System.out.println(a / 100.0);
System.out.println(Math.ceil(a / 100.0));
System.out.println((int) Math.ceil(a / 100.0));

Outputs:

See http://ideone.com/yhT0l

answered Dec 27 '10 at 18:02

moinudin

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5

this only if "a" is double – L.Grillo Jan 29 '16 at 10:20
1

^^ "a" needs to be a double or cast a double. – Codeversed Jan 25 '17 at 16:15
1

`a` is an `int` in this example, and it works as suggested. When doing `int / float` the result is a `float`, as demonstrated in the output. Try out the link. – dantiston Feb 22 '17 at 19:20

score 22 · Answer 2 · answered Dec 27 '10 at 18:07

22

I don't know why you are dividing by 100 but here my assumption int a;

int b = (int) Math.ceil( ((double)a) / 100);

or

int b = (int) Math.ceil( a / 100.0);

answered Dec 27 '10 at 18:07

score 13 · Answer 3 · answered Jan 31 '16 at 09:28

13

int RoundedUp = (int) Math.ceil(RandomReal);

This seemed to do the perfect job. Worked everytime.

answered Jan 31 '16 at 09:28

Liehan Els

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score 12 · Answer 4 · answered Jan 30 '20 at 13:17

10 years later but that problem still caught me.

So this is the answer to those that are too late as me.

This does not work

int b = (int) Math.ceil(a / 100);

Cause the result a / 100 turns out to be an integer and it's rounded so Math.ceil can't do anything about it.

You have to avoid the rounded operation with this

int b = (int) Math.ceil((float) a / 100);

Now it works.

score 2 · Answer 5 · answered Sep 04 '21 at 22:24

2

Just another option. Use basics of math:

Math.ceil(p / K) is same as ((p-1) // K) + 1

answered Sep 04 '21 at 22:24

omilus

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score 0 · Answer 6 · answered Dec 31 '19 at 20:27

0

The easiest way to do this is just: You will receive a float or double and want it to convert it to the closest round up then just do System.out.println((int)Math.ceil(yourfloat)); it'll work perfectly

answered Dec 31 '19 at 20:27

LouieAdauto

1

score -2 · Answer 7 · answered Jun 02 '17 at 07:21

-2

Assuming a as double and we need a rounded number with no decimal place . Use Math.round() function.
This goes as my solution .

double a = 0.99999;
int rounded_a = (int)Math.round(a);
System.out.println("a:"+rounded_a );

Output : 
a:1

answered Jun 02 '17 at 07:21

Ankit Chauhan

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This is a wrong answer, as it is asked here to round UP if a=0.2 the result will be 0 – Mohamed23gharbi Mar 06 '18 at 11:02

Java Round up Any Number

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