The task in Java seems to work well, and I believe you are handling some edge case incorrectly.

Check if you account for this part of the description:

Three conditions must be met for a valid experiment:

• Float parameter "h" in meters must be greater than 0
• Float parameter "bounce" must be greater than 0 and less than 1
• Float parameter "window" must be less than h.

If all three conditions above are fulfilled, return a positive integer, otherwise return -1.