xiv. What is "this" in Java? xv. Briefly describe the two uses of this in a constructor. xvi. Briefly describe what an activation record is and what it is used for. xvii. Java provides eight primitive wrapper classes. Explain what they are. xvili. Strings are immutable in Java. W hat does this mean? xix. Can a Java class have no constructors? (Explain yes or no.) xx, Given String s = new String( "cat"); and String t = "cat"., draw the box & arrow diagram for these two variables