ICollection and decimal.Divide for Java

Question

I imported a program from Github. It is written in C# and I convert the codes to Java. Everything works except one, the method that needs ICollection and decimal.Divide.

Are there ICollection and decimal.Divide for Java? Or alternatives?

I opened Apache NetBeans and it shows:

cannot find symbol
  symbol:   class ICollection
  location: class MathFormulas


cannot find symbol
  symbol:   variable decimal
  location: class MathFormulas