Question

1. In Lecture 8(ArrayList, Generics) , we discussed about creating a MyStack<E> class using the ArrayList<E> class that has the stack methods ( isEmpty(), getSize(), peek(), pop(), push(Object o), and toString( ) ) as shown in the following:

public class MyStack<E> {

private ArrayList<E> list = new ArrayList<>();

public int getSize() {

    return list.size();

}

public E peek() {

    return list.get(getSize() - 1);

}

public void push(E o) {

    list.add(o);

}

public E pop() {

    E o = list.get(getSize() - 1);

    list.remove(getSize() - 1);

    return o;

}

public boolean isEmpty() {

    return list.isEmpty();

}

@Override

public String toString() {

    return "stack: " + list.toString();

}

}

For this exercise, rewrite the MyStack <E> to the GenericStack<E> class that extends from ArrayList<E>.

import java.util.ArrayList;
import java.util.Iterator;

public class A6Q2 {
   public static void main(String[] args) {
/* After building your GenericStack from the ArrayList, add codes here to build the two Stacks
* (String and Integer) here
*/      
      
      
   }

   // Build a static class GenericStack<E> extends ArrayList

   static class GenericStack<E> extends ArrayList<E> {
  
         
         
   }
   }
Since this is a GenericStack<E> class, show that you can build a String (names) and Integer (Integer) stack using the same generic class.

In java please. Thank You

Answer 1

Given below is the code for the question. Please do rate the answer if it helped. Thank you.

import java.util.ArrayList;

public class A6Q2 {
   public static void main(String[] args) {
       /* After building your GenericStack from the ArrayList, add codes here to build the two Stacks
       * (String and Integer) here
       */
      
       GenericStack<String> fruits = new GenericStack<String>();
       fruits.push("apple");
       fruits.push("mango");
       fruits.push("banana");
       System.out.println("Top of fruits stack: " + fruits.peek());
       System.out.println("Size of fruits stack: " + fruits.size());
       System.out.println("Popped " + fruits.pop());
       System.out.println("Fruits stack contents: " + fruits);
      
       System.out.println("-------");
       GenericStack<Integer> nums = new GenericStack<Integer>();
       nums.push(2);
       nums.push(3);
       nums.push(4);
       System.out.println("Top of number stack: " + nums.peek());
       System.out.println("Size of number stack: " + nums.size());
       System.out.println("Popped " + nums.pop());
       System.out.println("Number stack contents: " + nums);

   }

   // Build a static class GenericStack<E> extends ArrayList

   static class GenericStack<E> extends ArrayList<E> {
      
       public E peek() {
           return get(size()-1);

       }

       public void push(E o) {
           add(o);
       }

       public E pop() {
           return remove(size() - 1);
       }

      
       @Override

       public String toString() {
           String s = "stack: ";
           for(int i = size()-1; i >= 0; i--) {
               if(i != size() - 1)
                   s += ", ";
               s += get(i);
           }
           return s;
          
       }

   }
}

output
----
Top of fruits stack: banana
Size of fruits stack: 3
Popped banana
Fruits stack contents: stack: mango, apple
-------
Top of number stack: 4
Size of number stack: 3
Popped 4
Number stack contents: stack: 3, 2