JNumberSpinner 
    abstract class JNumberSpinner<T : Number, Comparable<T>>(value: T, minValue: T?, maxValue: T?, stepSize: T) : JSpinner(source)
An abstract JSpinner for numbers that contains common logic for its subclasses.
Parameters
T
the type of number
value
the default value
minValue 
the smallest number that may be represented, or null if there is no limit
maxValue 
the largest number that may be represented, or null if there is no limit
stepSize 
the default value to increment and decrement by