Round Double to 1 decimal place kotlin: from 0.044999 to 0.1

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Round Double to 1 decimal place kotlin: from 0.044999 to 0.1

  1. Round Double to 1 decimal place kotlin: from 0.044999 to 0.1

    Finally I did what Andy Turner suggested, rounded to 3 decimals, then to 2 and then to 1:
    Answer 1:
    val number:Double = 0.0449999 val number3digits:Double = String.format("%.3f", number).toDouble() val number2digits:Double = String.format("%.2f", number3digits).toDouble() val solution:Double = String.format("%.1f", number2digits).toDouble()

  2. Round Double to 1 decimal place kotlin: from 0.044999 to 0.1

    Finally I did what Andy Turner suggested, rounded to 3 decimals, then to 2 and then to 1:
    Answer 1:
    val number:Double = 0.0449999 val number3digits:Double = String.format("%.3f", number).toDouble() val number2digits:Double = String.format("%.2f", number3digits).toDouble() val solution:Double = String.format("%.1f", number2digits).toDouble()

Solution 1

Finally I did what Andy Turner suggested, rounded to 3 decimals, then to 2 and then to 1:

Answer 1:

val number:Double = 0.0449999
val number3digits:Double = String.format("%.3f", number).toDouble()
val number2digits:Double = String.format("%.2f", number3digits).toDouble()
val solution:Double = String.format("%.1f", number2digits).toDouble()

Answer 2:

val number:Double = 0.0449999
val number3digits:Double = Math.round(number * 1000.0) / 1000.0
val number2digits:Double = Math.round(number3digits * 100.0) / 100.0
val solution:Double = Math.round(number2digits * 10.0) / 10.0

Result:

0.045 → 0.05 → 0.1

Note: I know it is not how it should work but sometimes you need to round up taking into account all decimals for some special cases so maybe someone finds this useful.

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Original Author edited Apr 10, 2020 at 10:52 Of This Content

Solution 2

The BigDecimal rounding features several RoundingModes, including those rounding up (away from zero) or towards positive infinity. If that’s what you need, you can perform rounding by calling setScale as follows:

val number = 0.0449999
val rounded = number.toBigDecimal().setScale(1, RoundingMode.UP).toDouble()
println(rounded) // 0.1

Note, however, that it works in a way that will also round anything between 0.0 and 0.1 to 0.1 (e.g. 0.000010.1).

The .toBigDecimal() extension is available since Kotlin 1.2.

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Original Author hotkey Of This Content

Solution 3

I know some of the above solutions work perfectly but I want to add another solution that uses ceil and floor concept, which I think is optimized for all the cases.

If you want the highest value of the 2 digits after decimal use below code.

import java.math.BigDecimal 
import java.math.RoundingMode
import java.text.DecimalFormat

here, 1.45678 = 1.46

fun roundOffDecimal(number: Double): Double? {
    val df = DecimalFormat("#.##")
    df.roundingMode = RoundingMode.CEILING
    return df.format(number).toDouble()
}

If you want the lowest value of the 2 digits after decimal use below code.

here, 1.45678 = 1.45

fun roundOffDecimal(number: Double): Double? {
    val df = DecimalFormat("#.##")
    df.roundingMode = RoundingMode.FLOOR
    return df.format(number).toDouble()
}

Here a list of all available flags: CEILING, DOWN, FLOOR, HALF_DOWN, HALF_EVEN, HALF_UP, UNNECESSARY, UP

The detailed information is given in docs

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Original Author Gaurang Goda Of This Content

Solution 4

1. Method (using Noelia’s idea):

You can pass the number of desired decimal places in a string template and make the precision variable this way:

fun Number.roundTo(
  numFractionDigits: Int
) = "%.${numFractionDigits}f".format(this, Locale.ENGLISH).toDouble()

2. Method (numeric, no string conversion)

fun Double.roundTo(numFractionDigits: Int): Double {
  val factor = 10.0.pow(numFractionDigits.toDouble())
  return (this * factor).roundToInt() / factor
}

One could create an overload for Float as well.

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Original Author Willi Mentzel Of This Content

Conclusion

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So This is all About This Tutorial. Hope This Tutorial Helped You. Thank You.

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Siddharth

I am an Information Technology Engineer. I have Completed my MCA And I have 4 Year Plus Experience, I am a web developer with knowledge of multiple back-end platforms Like PHP, Node.js, Python and frontend JavaScript frameworks Like Angular, React, and Vue.

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