Java and please explain the steps

Q2 (40 marks): Write a method called extract Triples. The method should take an ArrayList of integers as an input and extract only the numbers divisible by 3 in an ArrayList. Test your method in main method. For example, if the input ArrayList contained the values {4, 9, 8, 2, 18, 17, 72} then the method should return an ArrayList with the values 9, 18, 72}