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# java – Show decimal of a double only when needed

Questions:

I got this problem with double (decimals).
When a double = 1.234567 Then I use `String.format("%.3f", myString);`
So the result is 1.234

But when my double is 10
The result will be 10,000
I want this to be 10

Is their a way to say that he only needs to show the decimals when it is “usefull”?

Hope you guys can help me out with this.

Edit, for now I use something like this: `myString.replace(",000", "");`
But I think their is a more “friendly” code for this.

The DecimalFormat with the # parameter is the way to go:

``````public static void main(String[] args) {

double d1 = 1.234567;
double d2 = 2;
System.out.println(nf.format(d1));
System.out.println(nf.format(d2));
}
``````

Will result in

``````1.235
2
``````

Don’t use doubles. You can lose some precision. Here’s a general purpose function.

``````public static double round(double unrounded, int precision, int roundingMode)
{
BigDecimal bd = new BigDecimal(unrounded);
BigDecimal rounded = bd.setScale(precision, roundingMode);
return rounded.doubleValue();
}
``````

You can call it with

``````round(yourNumber, 3, BigDecimal.ROUND_HALF_UP);
``````

“precision” being the number of decimal points you desire.

Copy from Here.

``````double amount = 1.234567 ;