Java balanced expressions check {[()]}

Question

I am trying to create a program that takes a string as an argument into its constructor. I need a method that checks whether the string is a balanced parenthesized expressio

Answer 1

Please try this I checked it. It works correctly

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.util.HashMap;
import java.util.Map;
import java.util.Stack;
public class CloseBrackets {
    private static Map leftChar = new HashMap<>();
    private static Map rightChar = new HashMap<>();

    static {
        leftChar.put('(', '(');
        rightChar.put(')', '(');
        leftChar.put('[', '[');
        rightChar.put(']', '[');
        leftChar.put('{', '{');
        rightChar.put('}', '{');
    }

    public static void main(String[] args) throws IOException {
        BufferedReader bf = new BufferedReader(new InputStreamReader(System.in));
        String st = bf.readLine();
        System.out.println(isBalanced(st));
    }

    public static boolean isBalanced(String str) {

        boolean result = false;
        if (str.length() < 2)
            return false;
        Stack stack = new Stack<>();
        /* For Example I gave input 
         * str = "{()[]}" 
         */

        for (int i = 0; i < str.length(); i++) {

            char ch = str.charAt(i);
            if (!rightChar.containsKey(ch) && !leftChar.containsKey(ch)) {
                continue;
            }
            // Left bracket only add to stack. Other wise it will goes to else case 
            // For both above input how value added in stack 
            // "{(" after close bracket go to else case
            if (leftChar.containsKey(ch)) {
                stack.push(ch);
            } else {
                if (!stack.isEmpty()) {
                    // For both input how it performs
                    // 3rd character is close bracket so it will pop . pop value is "(" and map value for ")" key will "(" . So both are same . 
                    // it will return true. 
                    // now stack will contain only "{" , and travers to next up to end.
                    if (stack.pop() == rightChar.get(ch).charValue() || stack.isEmpty()) {
                        result = true;
                    } else {
                        return false;
                    }
                } else {
                    return false;
                }
            }

        }
        if (!stack.isEmpty())
            return result = false;
        return result;
    }
}