Question

I’m having an issue comparing a character in Java. I’m trying to find a valid binary number, so I’m passing a string with the binary digits into a function and making sure they’re either 0’s or 1’s. I loop through and check each character in the string, however, my function is telling me that it’s bad (even when I know I’ve given it a proper binary number).

Here is the function:

public boolean isValidBinary(String s) {
    //First we get the string length
    int strLen = s.length();
    //Now we loop through each character of the string
    for(int x = 0; x < strLen; x++) {
        //Assign the character to a variable each loopthrough
        char c = s.charAt(x);
        //Check if it's either a 0 or a 1
        if(c != '0' || c != '1') {
            return false;
        }
    }
    //This is reached when all char's have been evaluated as 0 or 1
    return true;
}

I have stared at this problem for quite some time and have been unable to figure it out, so any help would be appreciated.

Answer 1

That’s a logical error. You meant && instead of ||.

You could use a regular expression for this anyway:

// must contain at least one digit, and only 0 or 1
public boolean isValidBinary(String s)
{
    return s.matches("^[01]+$");
}