Java Stack ADT

You all are familiar with the data structure 'Stack'. The Stack ADT is same as Stack. It is a LIFO data structure where insertions and deletions always occur at the same end. This end is called the top of the stack and contains the element most recently inserted. The top of the stack is also the only element that can be inspected. Here we have designed a Java interface for ADT Stack.

Here is the code:

import java.lang.*;
import java.io.*;
import java.util.*;

interface MyInterface {
	int n = 20;

	public void pop();

	public void push();

	public void peek();

	public void display();
}

class StackImplementation implements MyInterface {
	int arr[] = new int[n];
	int top = -1;

	public void push() {
		try {
			DataInputStream dis = new DataInputStream(System.in);
			System.out.println("Enter Element");
			int ele = Integer.parseInt(dis.readLine());
			arr[++top] = ele;
		} catch (Exception e) {
			System.out.println("e");
		}
	}

	public void pop() {
		int popper = arr[top];
		top--;
		System.out.println("popped element " + popper);
	}

	public void peek() {
		int popper = arr[top];
		System.out.println("popped element " + popper);
	}

	public void display() {
		if (top < 0) {
			System.out.println("Stack is empty");
			return;
		} else {
			String str = " ";
			for (int i = 0; i <= top; i++)
				str = str + " " + arr[i];
			System.out.println("Elements are " + str);
		}
	}
}

class StackADT {
	public static void main(String arg[]) throws IOException {
		DataInputStream dis = new DataInputStream(System.in);
		StackImplementation stk = new StackImplementation();
		int menu = 0;
		do {
			System.out.println("1.push \n2.pop \n3.peek \n4.display \n5.Exit");
			System.out.println();
			System.out.print("Enter your choice: ");
			menu = Integer.parseInt(dis.readLine());
			switch (menu) {
			case 1:
				stk.push();
				break;
			case 2:
				stk.pop();
				break;
			case 3:
				stk.peek();
				break;
			case 4:
				stk.display();
				break;
			case 5:
				System.exit(0);
			}
		} while (menu <= 5);
		System.out.println();
	}
}

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