Creating a variable whose data type is ArrayListRectangle and adding 3 Rectangle objects I have them as r1,r2,r3.

Hello I need help doing the following:

Creating a variable whose data type is ArrayList<Rectangle> and adding 3 Rectangle objects I have them as r1,r2,r3. r1 having length and width of 1, r2 having length of 15 width of 30 and r3 having length of 15 width of 20. I also need to then make a loop to show the ArrayList for every element like the length,width and perimeter of the 3 rectangles. I'm just having the most trouble creating the variable with data ArrayList.