The BigDecimal(double) constructor can have unpredictable behaviors. It is preferable to use BigDecimal(String) or BigDecimal.valueOf(double).

Use with AISystem.out.println(new BigDecimal(135.69)); //135.68999999999999772626324556767940521240234375
System.out.println(new BigDecimal("135.69")); // 135.69
System.out.println(new BigDecimal("13۵.۶9")); // 135.69
System.out.println(BigDecimal.valueOf(135.69)); // 135.69

The documentation for BigDecimal(double) explains in detail:

1. The results of this constructor can be somewhat unpredictable. One might assume that writing new BigDecimal(0.1) in Java creates a BigDecimal which is exactly equal to 0.1 (an unscaled value of 1, with a scale of 1), but it is actually equal to 0.1000000000000000055511151231257827021181583404541015625. This is because 0.1 cannot be represented exactly as a double (or, for that matter, as a binary fraction of any finite length). Thus, the value that is being passed in to the constructor is not exactly equal to 0.1, appearances notwithstanding.
2. The String constructor, on the other hand, is perfectly predictable: writing new BigDecimal("0.1") creates a BigDecimal which is exactly equal to 0.1, as one would expect. Therefore, it is generally recommended that the String constructor be used in preference to this one.
3. When a double must be used as a source for a BigDecimal, note that this constructor provides an exact conversion; it does not give the same result as converting the double to a String using the Double.toString(double) method and then using the BigDecimal(String) constructor. To get that result, use the static valueOf(double) method.

If you are bothered about having to create the BigDecimal over two lines, BigDecimal has constructors that take Int that you can call directly:

 val bigDecimalInt = BigDecimal(1)

This is fine for integer values, BUT for floating-point values like Double the constructor and toBigDecimal actually behave differently. The constructor creates a BigDecimal value of the Double value passed in, which will be "incorrect" if that value is not exactly representable in floating-point arithmetic. toBigDecimal converts the value to a String and then uses that which gives the "correct" value

val doubleNum:Double = 0.1
println(doubleNum.toBigDecimal()) // prints 0.1

val bigDecimal:BigDecimal = BigDecimal(0.1)
println(bigDecimal)               // prints 0.1000000000000000055511151231257827021181583404541015625

If none of that makes sense, you probably need to read about Floating Point Arithmetic, this is a common problem affecting all/most programming languages

So toBigDecimal is a safer option