How to floor a number to two decimal places?

Question

I'm trying to floor a double data type number to two decimal places but I only get one instead when I enter a number like 150.

For example if I type this :

double num = 150.52152;

Math.floor(num * 100) / 100;

I get 150.52 and that's okay!

But If I enter double num = 150 I get 150.0 instead of 150.00

How do I solve this?

150.0 is the same as 150.00, it's just a matter of how the value is presented. You need to use a number formatter if you want a specific output — Joakim Danielson, Mar 07 '21 at 14:49

score 3 · Answer 1 · edited Mar 07 '21 at 15:24

You could do it in two ways

Using String.format

String.format("%.2f",floorValue)

Using DecimalFormat

new DecimalFormat("#,##0.00").format(floorValue)

I recommend you store new DecimalFormat("#,##0.00") into a final variable and use it whenever required rather than creating a new DecimalFormat object every time formatting is required.

Demo:

import java.text.DecimalFormat;
import java.text.NumberFormat;

public class Main {
    public static void main(String[] args) {
        final NumberFormat format = new DecimalFormat("#,##0.00");// Do it once

        double floorValue = 150;
        System.out.println(format.format(floorValue));// Use it wherever you need to

        // Alternatively
        System.out.printf(String.format("%.2f", floorValue));
    }
}

Output:

150.00
150.00

score 1 · Answer 2 · answered Mar 07 '21 at 14:49

1

Controlling the number of decimal places is a function of converting the decimal to a String. Remember you are viewing a value in base 10 from base 2. Not every such value is representable (for example System.out.println(0.05+0.1);). Instead, use String formatting. Like,

System.out.printf("%.02f%n", 150.0);

or

System.out.printf("%.02f%n", 0.05 + 0.1);

answered Mar 07 '21 at 14:49

Elliott Frisch

198,278
20
158
249

Thank you very much. I forgot to mention I want to print it in a return statemen like "Purchase value : " + num... How do I apply the same thing then? – Mar 07 '21 at 14:56
`return String.format("Purchase value : %.02f", 150.0);` – Elliott Frisch Mar 07 '21 at 14:58
1

@PohovaniVodokotlic see this https://stackoverflow.com/help/someone-answers. – Dren Mar 07 '21 at 15:02

Rabbitminers · Answer 3 · 2021-03-07T15:12:01.343

0

To display your awnser at all times with two values displayed after the decimal point you have two output methods. Your first is as follows:

System.out.printf("%.2f", <YOUR VALUE>);

%.2F calls two decimals in a float which is first defined by printf (print float) this cannot be removed as a integer cannot be a decimal.

Yours second option is to use a decimal format. For example:

// First define your fromat as decimalFormat
DecimalFormat decimalFormat = new DecimalFormat();
// Define number of digits after the decimal point in your case two
decimalFormat.setMaximumFractionDigits(2);
// Print out our result now formated in what we have just defined
System.out.println(decimalFormat.format(<YOUR VALUE>));

Although you output a string it can take a float (you may need to put "f" after your value to make sure it is defined).

Hope this is informative.

edited Mar 07 '21 at 15:12

answered Mar 07 '21 at 14:49

Rabbitminers

315
3
11

What is `round`, how will this display 2 decimals when rounding 150? – Joakim Danielson Mar 07 '21 at 14:52
Just use this its easier `System.out.printf("%.2f", val);` – Rabbitminers Mar 07 '21 at 14:54
What is `val`? (I know what it is but please post a complete and useful answer) – Joakim Danielson Mar 07 '21 at 14:56
Please see this here https://stackoverflow.com/questions/2538787/how-to-print-a-float-with-2-decimal-places-in-java#:~:text=In%20short%2C%20the%20%25.,the%20format%20specifier%20(%20%25%20). It goes into far more detail than I could in a comment – Rabbitminers Mar 07 '21 at 14:56
2

It’s not my question and I know exactly how to handle this problem. I am asking of _you_ to edit your answer so it is a correct and meaningful answer. – Joakim Danielson Mar 07 '21 at 14:59
Right give me a few minutes – Rabbitminers Mar 07 '21 at 15:03
Let us [continue this discussion in chat](https://chat.stackoverflow.com/rooms/229618/discussion-between-rabbitminers-and-joakim-danielson). – Rabbitminers Mar 07 '21 at 15:20
1

This answer is now a duplicate so please remove it. – Joakim Danielson Mar 07 '21 at 15:22

score 0 · Answer 4 · answered Mar 07 '21 at 16:07

You can also do it like this (but I would prefer String.format or System.out.printf). Note that trailing zeroes won't be displayed so 100.10230 would show as 100.1.

Generate some data

Random r =  new Random();
double[] dbls = r.doubles(10).map(d->d*1000).toArray();

Print the values

for (double d : dbls) {
    double df = (int)(d*100+.5)/100.;
    System.out.println(d + " --> " + df);
}

Prints something similar to this.

738.2358190119878 --> 738.24
902.7752505591593 --> 902.78
467.26349962571953 --> 467.26
503.2049813704648 --> 503.2
20.288046322504805 --> 20.29
409.10379837674714 --> 409.1
559.2821881121522 --> 559.28
288.5513513499909 --> 288.55
124.07583289719682 --> 124.08
535.1799354550361 --> 535.18

The trailing zeroes are what the question is about... – Joakim Danielson Mar 07 '21 at 17:33 — Joakim Danielson, Mar 07 '21 at 17:33

How to floor a number to two decimal places?

4 Answers4