Import javautil public interface bagadt void

A Bag is a general unordered container of items where duplicates are allowed.
import java.util.*;
public interface BagADT {
void add(Object item);
Object remove() throws NoSuchElementException;
boolean isEmpty();
}
 Why are we using the Object class in our BagADT interface?
2. Bag ADT Implementation
Steps public class ArrayBag implements BagADT {
private Object[] items;
private int numItems;
public ArrayBag() {
items = new Object[100];
numItems = 0;
}
void add(Object item) { ... }
Object remove() throws NoSuchElementException { ... }
boolean isEmpty(){ return numItems == 0; }
}

Copyright 2014-2016 Jim Skrentny CS 367 (S16): L2 - 3
Use - BagADT and Casting
Using a general ADT and its implementation to instantiate a container:
 Write a statement that makes a Bag ADT container named bag .
 Assume Die is a class representing dice and has a zero parameter constructor.
Write a code fragment that adds 6 dice to bag .
 Assume the bag has had items added to it. Why doesn’t the following code compile?
while (!bag.isEmpty()) {
Die myDie = bag.remove();
myDie.roll();
}

Copyright 2014-2016 Jim Skrentny CS 367 (S16): L2 - 4
Java Generics - A Better Way to Make a General Bag ADT
What changes are needed to make the interface below generic?
import java.util.*;
public interface BagADT {
void add(Object item);
Object remove() throws NoSuchElementException;
boolean isEmpty();
}
1.
2.

Copyright 2014-2016 Jim Skrentny CS 367 (S16): L2 - 5
Implementation - Generic BagADT
What changes are needed to make the implementation below generic?
public class ArrayBag implements BagADT {
private Object[] items;
private int numItems;
public ArrayBag() {
items = new Object[100];
numItems = 0;
}
boolean isEmpty(){ return numItems == 0; }
void add(Object item) { ... }
Object remove() throws NoSuchElementException { ... }
}
1.