Question

I need the following code to have a default constructor of BalancedString that initializes str to the empty string and resets a counter to 0 The class’s one arguement constructor passes a string s to str and resets counter to zero. The BalancedString class also provides a boolean method which is boolean balanced() that returns true if a string contains a balanced amount of parenthesis

import java.util.*;
public class BalancedString {
    private static String str;


    public BalancedString()
    {
        str = "";

    }

    public BalancedString(String s)
    {
        s = "";
        str = s;

}



public boolean balanced(){

    return true;

}
public static void main(String[] args) {
    int n = 0;
    CounterFancy.setCounter(n);
    Scanner input = new Scanner(System.in);
    System.out.println("Enter a string that has any number of Left and right Parenthesis");
    String s = input.next();


        if (s.indexOf('(') != -1)

            CounterFancy.incCounter();

        if (s.indexOf(')') != -1)

            CounterFancy.decCounter();


    int counterValue = CounterFancy.getCounter();
    if (counterValue == 0)
        System.out.println("The string is Balanced");
    else 
        System.out.println("The string is NOT Balanced");
    input.close();
}

public String getStr()
{
    return str;
}
public String setStr(String s)
{
    str = s;
    return str;
}

}

AND the following is the other project that i got the CounterFancy classes from, but the problem is above^^ why is this only outputing that it is balanced

//Joe D'Angelo
//CSC 131-03
//Chapter 10 Programming Assignment 5a.
//Takes the user's input of whether they want the counter to be negative or positive and outputs
//10 values of the user's selected input, then restarts the counter at 0
import java.util.*;
public class CounterFancy { //I messed up the first time and had to change FancyCounter to CounterFancy that is why this is changed

    private static int counter;

    public CounterFancy()
    {
        counter = 0;        
    }

    public  CounterFancy(int n){
        counter = n;
    }

    public static int incCounter() //inc stands for increment
    {
            counter++;
        return counter;
    }
    public static int decCounter() //dec stands for decrement
    {
        counter--;
        return counter;
    }

    public static void main(String[] args){
        Scanner input = new Scanner(System.in);
        System.out.println("Press 1 for Possitive or Press 2 for Negative");
        int reply = input.nextInt();

        if (reply == 1)
        {
        for (int i = 1; i <=10; i ++)
        System.out.println("counter: " + CounterFancy.incCounter());
        CounterFancy.setCounter(5);
        System.out.println("Counter: " + CounterFancy.getCounter());

        }

        if (reply == 2)
        {
            for (int i = 1; i <=10; i ++)
                System.out.println("counter: " + CounterFancy.decCounter());
            CounterFancy.setCounter(5);
            System.out.println("Counter: " + CounterFancy.getCounter());

        }
        input.close();
        }



    public static int getCounter()
    {
        return counter;
    }

    public static void setCounter(int n)
    {
        counter = 0;
    }

}

Answer 1

You are making a couple of mistakes in your BalancedString class definition. First, the str field should not be static. By making it static, all instances share the same str field.

Second, and perhaps more critical, you are not constructing your BalancedString properly. You are setting the argument back to the empty string every time!

public BalancedString(String s) {
        s = ""; // THIS LINE SHOULD NOT BE HERE!
        str = s;
}

Finally, your balanced() method is simply returning true regardless of the string. You need to implement some logic here.

Regarding the main program: you need to loop through all the characters, increment for each '(' and decrement for each ')' character. Instead of this:

if (s.indexOf('(') != -1)

        CounterFancy.incCounter();

if (s.indexOf(')') != -1)

    CounterFancy.decCounter();

You should have a loop like this:

for (int i = 0; i < s.length(); ++i) {
    char c = s.charAt(i);
    if (c == '(')
        CounterFancy.incCounter();
    else if (c == ')')
        CounterFancy.decCounter();
}