Java decimal formatting using String.format?

Question

I need to format a decimal value into a string where I always display at lease 2 decimals and at most 4.

So for example

"34.49596" would be "34.4959" 
"49.3" would be "49.30"

Can this be done using the String.format command?
Or is there an easier/better way to do this in Java.

Solution 1

You want java.text.DecimalFormat.

DecimalFormat df = new DecimalFormat("0.00##");
String result = df.format(34.4959);

Solution 2

Yes you can do it with String.format:

String result = String.format("%.2f", 10.0 / 3.0);
// result:  "3.33"

result = String.format("%.3f", 2.5);
// result:  "2.500"

Solution 3

Here is a small code snippet that does the job:

double a = 34.51234;

NumberFormat df = DecimalFormat.getInstance();
df.setMinimumFractionDigits(2);
df.setMaximumFractionDigits(4);
df.setRoundingMode(RoundingMode.DOWN);

System.out.println(df.format(a));

Solution 4

java.text.NumberFormat is probably what you want.

Solution 5

NumberFormat and DecimalFormat are definitely what you want. Also, note the NumberFormat.setRoundingMode() method. You can use it to control how rounding or truncation is applied during formatting.

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Comments

[Adeel Ansari]

Follow the same example you will get the wrong result. You need to use the RoundingMode.DOWN for this particular example. Otherwise, it uses HALF_EVEN. No, negative though.

[Adeel Ansari]

No negatives, but your code fails for the very first example, given by the original poster. Need to use RoundingMode.DOWN, otherwise it uses HALF_EVEN by default, I suppose.

[milosmns]

This may not be the correct answer to the question asked, but it's the answer I came here to find. Thanks!