java stack

JAVA STACK OPERATIONS:-

1. Object push(Object element) : Pushes an element on the top of the stack.

2. Object pop() : Removes and returns the top element of the stack. An ‘EmptyStackException’ exception is thrown if we call pop() when the invoking stack is empty.

3. Object peek( ) : Returns the element on the top of the stack, but does not remove it.

4. boolean empty() : It returns true if nothing is on the top of the stack. Else, returns false.

5. int search(Object element) : It determines whether an object exists in the stack. If the element is found, it returns the position of the element from the top of the stack. Else, it returns -1.

package com.elegant.ds.stack;

import java.util.Scanner;

public class StackDemo {

    @SuppressWarnings("resource")
    public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);
        System.out.println("Enter the size of stack");
        int size = scanner.nextInt();
        StackDemoTest stack = new StackDemoTest(size);
        boolean yes = true;
        do {
            System.out.println("1. Push");
            System.out.println("2. Pop");
            System.out.println("3. Check Full");
            System.out.println("4. Check Empty");
            System.out.println("5. Delete Middle");
            System.out.println("6. Peek");
            System.out.println("7. Display");
            System.out.println("8. Exit");

            int choice = scanner.nextInt();
            switch (choice) {
            case 1:
                stack.push(scanner.nextInt());
                break;

            case 2:
                stack.pop();
                break;

            case 3:
                System.out.println(stack.isFull());
                break;

            case 4:
                System.out.println(stack.isEmpty());
                break;

            case 5:
                stack.deleteMiddle();
                break;

            case 6:
                stack.peek();
                break;

            case 7:
                stack.display();
                break;
            case 8:
                yes = false;
                break;

            default:
                System.out.println("Invalid Choice!");
                break;
            }
        } while (yes);
    }
}

class StackDemoTest {

    int top = -1;
    int size = 0;
    int[] stackArray = null;

    public StackDemoTest() {

    }

    public StackDemoTest(int size) {
        stackArray = new int[size];
        top = -1;
        this.size = size;
    }

    public void push(int item) {
        if (isFull()) {
            System.out.println("Stack is Full");
            return;
        }
        stackArray[++top] = item;
        display();
    }

    public void pop() {
        if (isEmpty()) {
            System.out.println("Stack is Empty");
            return;
        }
        System.out.println("poped item is " + stackArray[top]);
        --top;
        display();
    }

    public void display() {

        if (isEmpty()) {
            System.out.println("Stack is Empty");
            return;
        }
        System.out.println("Items in stack is :-");
        for (int i = 0; i <= top; i++) {
            System.out.print(stackArray[i] + " ");
        }
        System.out.println();
    }

    public void deleteMiddle() {
        if (isEmpty()) {
            System.out.println("Stack is Empty ");
            return;
        }
        System.out.println("Deleted Element is : " + stackArray[top / 2]);
        for (int i = top / 2; i < top; i++) {
            stackArray[i] = stackArray[i + 1];
        }
        top--;
        display();
    }

    public void peek() {
        if (isEmpty()) {
            System.out.println("Stack is empty ");
            return;
        }
        System.out.println("Peek item is : " + stackArray[top]);
    }

    public boolean isEmpty() {
        return top <= -1;
    }

    public boolean isFull() {
        return top + 1 >= size;
    }
}