Question: Please heo me with this questions please thank you so much

Question 1: Write java statements that use a for each loop to cycle through all the elements in an ArrayList of doubles named grades.

Question 2: Write a java method named average. The method should take an ArrayList of Integers as a parameter, compute the average of the elements in the ArrayList and return the average to the calling method

Question 3: What is the main disadvantage of an ArrayList

Solve these problems in details and provide examples to support your rationale.