Question

• JAVA
• Write a class to implement the Stack ADT using an array as the underlying structure.
• Implement the pop function so that pop not only removes the top item from the stack, but also reports that value.

Answer 1

CODE

import java.util.*;

class ArrayBasedStack
{
    protected int arr[];
    protected int top, size, len;
  
    public ArrayBasedStack(int n)
    {
        size = n;
        len = 0;
        arr = new int[size];
        top = -1;
    }
  
    public boolean isEmpty()
    {
        return top == -1;
    }
  
    public boolean isFull()
    {
        return top == size -1 ;      
    }
  
    public int getSize()
    {
        return len ;
    }
  
    public int peek()
    {
        if( isEmpty() )
            throw new NoSuchElementException("Underflow Exception");
        return arr[top];
    }
  
    public void push(int i)
    {
        if(top + 1 >= size)
            throw new IndexOutOfBoundsException("Overflow Exception");
        if(top + 1 < size )
            arr[++top] = i;
        len++ ;
    }
  
    public int pop()
    {
        if( isEmpty() )
            throw new NoSuchElementException("Underflow Exception");
        len-- ;
        return arr[top--];
    }
}