4.Lab4.2 Modified XML code (Solved)

import java.io.BufferedReader;
import java.io.InputStreamReader;
import java.util.NoSuchElementException;

interface Stack<E> {

    // The elements of the Stack are any kind of objects

    // Access methods:

    public boolean isEmpty();
    // Returns true only if the stack is empty.

    public E peek();
    // Returns the element on the top od the stack.

    // Transformation methods:

    public void clear();
    // Clears the stack.

    public void push(E x);
    // Adds x on the top of the stack.

    public E pop();
    // Removes and returns the element on the top.
}

class ArrayStack<E> implements Stack<E> {
    private E[] elems;
    private int depth;

    @SuppressWarnings("unchecked")
    public ArrayStack(int maxDepth) {
        // Creating new empty stack
        elems = (E[]) new Object[maxDepth];
        depth = 0;
    }


    public boolean isEmpty() {
        // Returns true only if the stack is empty.

        return (depth == 0);
    }


    public E peek() {
        // Returns the element on the top od the stack.
        if (depth == 0)
            throw new NoSuchElementException();
        return elems[depth - 1];
    }


    public void clear() {
        // Clears the stack.
        for (int i = 0; i < depth; i++) elems[i] = null;
        depth = 0;
    }


    public void push(E x) {
        // Adds x on the top of the stack.
        elems[depth++] = x;
    }


    public E pop() {
        // Removes and returns the element on the top.
        if (depth == 0)
            throw new NoSuchElementException();
        E topmost = elems[--depth];
        elems[depth] = null;
        return topmost;
    }
}

public class CheckXML {

    public static void main(String[] args) throws Exception {

        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
        String s = br.readLine();
        int n = Integer.parseInt(s);
        String[] redovi = new String[n];

        for (int i = 0; i < n; i++)
            redovi[i] = br.readLine();

        int isValid = 1;
        ArrayStack<String> stackOpenTags = new ArrayStack<String>(1000);

        for (int i = 0; i < redovi.length; i++) {
            if (redovi[i].charAt(0) == '[' &&
                redovi[i].charAt(1) != '/' &&
                redovi[i].charAt(redovi[i].length() - 1) == ']') {
                stackOpenTags.push(redovi[i]);
            }
            if (redovi[i].charAt(1) == '/') {
                if (!stackOpenTags.isEmpty()){
                    String temp = stackOpenTags.pop();
                    String opening = temp.substring(1, temp.length()-1);

                    String closing = redovi[i].substring(2, redovi[i].length()-1);

                    if (!opening.equals(closing)){
                        isValid = 0;
                        break;
                    }

                } else {
                    isValid = 0;
                    break;
                }
            }
        }


        System.out.println(isValid);

        br.close();
    }
}