Issue with Program that builds strings

Question

I wrote a program that performs certain operations (AND, OR, NOR, NAND, NOT, XOR) on two binary numbers and returns the result. I used a stringbuilder to produce the result. The program's method uses a for loop to look through each character in BinaryA (because they both have the same length) and then uses an algorithim based on a truth table to get the result.

The only issue i'm having is that the result keeps outputting either 00000000 or 11111111 as a result. I'm not sure what my logic issue is:

public class Driver {

public static void main(String[] args) {
    String Operator = "AND";
    String binA = "10110101";
    String binB = "00110001";

    System.out.println(Operator + " and binary numbers " + binA + " and " + binB + " result in the output " + doOperation(Operator, binA, binB));

}

public static StringBuilder doOperation(String Operator, String BinaryA, String BinaryB)
{
    StringBuilder result = new StringBuilder();

    for(int i = 0; i < BinaryA.length(); i++)
    {
        if(Operator.equals("AND"))
        {
            if(BinaryA.equals("1") && BinaryB.equals("1"))
                result.append('1');
            else
                result.append('0');
        }
        else if (Operator.equals("OR"))
        {
            if(BinaryA.equals("0") && BinaryB.equals("0"))
                result.append('0');
            else
                result.append('1');

        }
        else if (Operator.equals("NAND"))
        {
            if(BinaryA.equals("1") && (BinaryB.equals("1")))
                result.append('0'); 
            else
                result.append('1');
        }
        else if (Operator.equals("NOR"))
        {
            if(BinaryA.equals("0") && (BinaryB.equals("0")))
                result.append('1');
            else
                result.append('0');
        }
        else if (Operator.equals("XOR"))
        {
            if(BinaryA.equals("1") && BinaryB.equals("0") || (BinaryA.equals("0")) && BinaryB.equals("1"))
                result.append('1');
            else
                result.append('0');

        }
    }
    return result;

}

}

OUTPUT: AND and binary numbers 10110101 and 00110001 result in the output 00000000

Parsing them as numbers would be a lot more efficient and less error-prone. — initramfs
– initramfs, Commented Feb 7, 2015 at 21:02

Óscar López · Accepted Answer · 2015-02-07 20:58:27Z

4

This won't work, BinaryA and BinaryB are Strings, but you want to compare individual chars:

if (BinaryA.equals("1") && BinaryB.equals("1"))

Instead, you should do a char-by-char traversal, something like this:

if (BinaryA.charAt(i) == '1' && BinaryB.charAt(i) == '1')

Change all the comparisons so they operate on the single char pointed by the current i index.

answered Feb 7, 2015 at 20:58

Óscar López

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1 Comment

c0der Over a year ago

Perfect!!!!! I made Such a silly mistake, but it happens to the best of us I suppose.

Saimir · Accepted Answer · 2015-02-07 21:06:42Z

2

You should try this :

if(Operator.equals("AND"))
    {
        if(BinaryA.charAt(i)=='1'&&  BinaryB.charAt(i)=='')
            result.append('1');
        else
            result.append('0');
    }
    else if (Operator.equals("OR"))
    {
        if(BinaryA.charAt(i)=='0' && BinaryB.charAt(i)=='0')
            result.append('0');
        else
            result.append('1');

    }

answered Feb 7, 2015 at 21:06

Saimir

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1 Comment

Saimir Over a year ago

you are right but i think is 1 not 0, any way. you are welcomed @c0der!

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