Question

What is the type of code in line 16? The answer is supposed to be Object. Can someone give me an in depth explanation why?

What is the type of the code in line 16: 1 2 package app: import java.util.ArrayList; public class Controller { 3 4 5 6 7 8 public static void main(String[] args) { 9 BookBag my Bookbag = new BookBag(); Book myBook = new Book("123 of Java"); Phone myPhone = new Phone (14.2); 10 11 12 12 13 14 15 16 17 18 19 myBookBag.getItems ().add(myBook); myBookBag.getItems ().add(myPhone); /* myBookBag.getItems(); myBookBag.getItems().get(0); myBookBag.getItems ().get(1); (Book) myBookBag.getItems().get(0); (Phone) my Bookbag.getItems().get(1); ((Book) myBookBag.getItems().get(0)).getTitle(); ((Phone) myBookBag.getItems().get(1)).getVersion(); */ }//end main }//end class EEEEE //=========== package app; import java.util.ArrayList; public class BookBag { private ArrayList items; public BookBag() { items = new ArrayListo(); } public ArrayList getItems() { return items; } }//end class ========= //========= package app; 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 53 54 54 55 56 57 57 50 58 59 ca 00 61 CO 62 52 63 CA 64 CC 65 CC 66 67 50 68 69 70 71 72 public class Book { private String title; public Book (String title) { this.title = title; } public String getTitle() { return title; } }//end class //======== package app: public class Phone { private double version; public Phone( double version) { this.version = version; } public double getVersion(){ return version; } }//end class

Answer 1

Line 16:- myBookBag.getItems().get(0)

Explanation:- myBookBag is object of class BookBag. getItems() is a method of
class BookBag. myBookBag.getItems() return the ArrayList named
items. (ArrayList(items) is created at the time of creating an
object(myBookBag) of class BookBag)
  
myBookBag.getItems().get(0) return the first element of the
arrayList(items).

Note:- get(index) is used to access the element(present at index) of the ArrayList.