Displaying decimal values with a predefined format - kotlin

Question

I am getting below sample values from my calculation result and I have to display is in 2 decimal points without rounding it.
-0.00123,
-2.222154,
-23.154,
-2.13,
-0.10001,
-10.0012,
-1.0023,
0.23,
0.56474,
1.000,
11.1111,
1.89566
I am using Decimal Format : 0.00 so,
while using "0.00" , its displaying value for -0.00128 but not displaying for -2.2386
Which should be the proper decimal format as per my need ? I have gone through the documentation here : https://developer.android.com/reference/java/text/DecimalFormat#:~:text=A%20DecimalFormat%20comprises%20a%20pattern,read%20from%20localized%20ResourceBundle%20s.
But, Still having confusion so posted question here.

Answer 1

You can use BigDecimal with the desired scale (e.g. 2) and rounding mode (e.g HALF_UP) like so:
import java.math.BigDecimal
import java.math.RoundingMode
fun main() {
val roundingMode = RoundingMode.HALF_UP
val doubles: List<Double> = listOf(
-0.00123, -2.222154, -23.154, -2.13, -0.10001, -10.0012,
-1.0023, 0.23, 0.56474, 1.000, 11.1111, 1.89566
)
doubles.map { BigDecimal(it).setScale(2, roundingMode) }.also { println(it) }
// [0.00, -2.22, -23.15, -2.13, -0.10, -10.00, -1.00, 0.23, 0.56, 1.00, 11.11, 1.90]
}
Same approach in a more functional flavour (partial function instead of constants):
val fancyRound: (scale: Int, roundingMode: RoundingMode) -> (Double) -> BigDecimal =
{ scale, roundingMode ->
{ d -> BigDecimal(d).setScale(scale, roundingMode) }
}
fun main() {
...
val myRound = fancyRound(2, RoundingMode.HALF_UP)
doubles.map { myRound(it) }.also { println(it) }
}

Answer 2

You could try:
import java.math.RoundingMode;
import java.text.DecimalFormat;
class Scratch {
public static void main(String[] args) {
String srcNumber = "-2.2386";
DecimalFormat formatter = new DecimalFormat("0.00");
formatter.setRoundingMode(RoundingMode.DOWN);
srcNumber = formatter.format(Double.valueOf(srcNumber));
System.out.println(srcNumber);
}
}