/*
============================================================
Convert a decimal-like value to Long in Scala.
This program demonstrates:
• Conversion using Math.round() for rounding.
• Conversion using toLong for truncation.
• Conversion using BigDecimal.toLongExact for strict conversion.
• A helper method that prints all conversion styles.
Notes:
• Scala does not have a separate "decimal" type; Double and BigDecimal
are used for decimal values.
• Math.round returns a Long.
• toLong truncates the fractional part.
• BigDecimal.toLongExact throws if the value is fractional or out of range.
============================================================
*/
object DecimalToLongDemo {
// Rounds a Double to Long
def convertDoubleToLong(value: Double): Long =
Math.round(value)
// Truncates a Double to Long
def castDoubleToLong(value: Double): Long =
value.toLong
// Converts BigDecimal using truncation
def convertBigDecimalToLong(value: BigDecimal): Long =
value.toLong
// Converts BigDecimal strictly (throws if fractional)
def convertBigDecimalExact(value: BigDecimal): Either[String, Long] =
try {
Right(value.toLongExact)
} catch {
case _: ArithmeticException =>
Left("ERROR — fractional or out of range")
}
// Prints conversion styles for Double
def showDoubleConversions(value: Double): Unit = {
println(s"Input decimal (Double): $value")
println(s"Rounded (Math.round): ${convertDoubleToLong(value)}")
println(s"Truncated (toLong): ${castDoubleToLong(value)}")
println()
}
// Prints conversion styles for BigDecimal
def showBigDecimalConversions(value: BigDecimal): Unit = {
println(s"Input decimal (BigDecimal): $value")
println(s"Truncated (toLong): ${convertBigDecimalToLong(value)}")
convertBigDecimalExact(value) match {
case Right(v) => println(s"Exact (toLongExact): $v")
case Left(err) => println(s"Exact (toLongExact): $err")
}
println()
}
def main(args: Array[String]): Unit = {
// Double examples
showDoubleConversions(12.7)
showDoubleConversions(12.3)
showDoubleConversions(-5.8)
showDoubleConversions(42.0)
// BigDecimal examples
showBigDecimalConversions(BigDecimal("12.7"))
showBigDecimalConversions(BigDecimal("42"))
showBigDecimalConversions(BigDecimal("-5.8"))
}
}
/*
run:
Input decimal (Double): 12.7
Rounded (Math.round): 13
Truncated (toLong): 12
Input decimal (Double): 12.3
Rounded (Math.round): 12
Truncated (toLong): 12
Input decimal (Double): -5.8
Rounded (Math.round): -6
Truncated (toLong): -5
Input decimal (Double): 42.0
Rounded (Math.round): 42
Truncated (toLong): 42
Input decimal (BigDecimal): 12.7
Truncated (toLong): 12
Exact (toLongExact): ERROR — fractional or out of range
Input decimal (BigDecimal): 42
Truncated (toLong): 42
Exact (toLongExact): 42
Input decimal (BigDecimal): -5.8
Truncated (toLong): -5
Exact (toLongExact): ERROR — fractional or out of range
*/
