Implement two stacks in an array Java

PROGRAM TO IMPLEMENT TWO STACKS IN AN ARRAY

class TwoStacks {

    int size;

    int top1, top2;

    int arr[];

  

    // Constructor

    TwoStacks(int n)

    {

        arr = new int[n];

        size = n;

        top1 = -1;

        top2 = size;

    }

  

    // Method to push an element x to stack1

    void push1(int x)

    {

        // There is at least one empty space for

        // new element

        if (top1 < top2 - 1) {

            top1++;

            arr[top1] = x;

        }

        else {

            System.out.println("Stack Overflow");

            System.exit(1);

        }

    }

  

    // Method to push an element x to stack2

    void push2(int x)

    {

        // There is at least one empty space for

        // new element

        if (top1 < top2 - 1) {

            top2--;

            arr[top2] = x;

        }

        else {

            System.out.println("Stack Overflow");

            System.exit(1);

        }

    }

  

    // Method to pop an element from first stack

    int pop1()

    {

        if (top1 >= 0) {

            int x = arr[top1];

            top1--;

            return x;

        }

        else {

            System.out.println("Stack Underflow");

            System.exit(1);

        }

        return 0;

    }

  

    // Method to pop an element from second stack

    int pop2()

    {

        if (top2 < size) {

            int x = arr[top2];

            top2++;

            return x;

        }

        else {

            System.out.println("Stack Underflow");

            System.exit(1);

        }

        return 0;

    }

  

    // Driver program to test twoStack class

    public static void main(String args[])

    {

        TwoStacks ts = new TwoStacks(5);

        ts.push1(5);

        ts.push2(10);

        ts.push2(15);

        ts.push1(11);

        ts.push2(7);

        System.out.println("Popped element from"

                           + " stack1 is " + ts.pop1());

        ts.push2(40);

        System.out.println("Popped element from"

                           + " stack2 is " + ts.pop2());

    }

}




OUTPUT:

Popped element from stack1 is 11
Popped element from stack2 is 40

CREDITS: https://www.geeksforgeeks.org/implement-two-stacks-in-an-array/