Question

Basically what I’m trying to do is take a String, and replace each letter in the alphabet inside, but preserving any spaces and not converting them to a “null” string, which is the main reason I am opening this question.

If I use the function below and pass the string “a b”, instead of getting “ALPHA BETA” I get “ALPHAnullBETA”.

I’ve tried all possible ways of checking if the individual char that is currently iterated through is a space, but nothing seems to work. All these scenarios give false as if it’s a regular character.

public String charConvert(String s) {

    Map<String, String> t = new HashMap<String, String>(); // Associative array
    t.put("a", "ALPHA");
    t.put("b", "BETA");
    t.put("c", "GAMA");
    // So on...

    StringBuffer sb = new StringBuffer(0);
    s = s.toLowerCase(); // This is my full string

    for (int i = 0; i < s.length(); i++) {
        char c = s.charAt(i);

        String st = String.valueOf(c);
        if (st.compareTo(" ") == 1) {
            // This is the problematic condition
            // The script should just append a space in this case, but nothing seems to invoke this scenario
        } else {
            sb.append(st);
        }

    }

    s = sb.toString();

    return s;
}

Answer 1

compareTo() will return 0 if the strings are equal. It returns a positive number of the first string is “greater than” the second.

But really there’s no need to be comparing Strings. You can do something like this instead:

char c = s.charAt(i);

if(c == ' ') {
    // do something
} else {
    sb.append(c);
}

Or even better for your use case:

String st = s.substring(i,i+1);
if(t.contains(st)) {
    sb.append(t.get(st));
} else {
    sb.append(st);
}

To get even cleaner code, your Map should from Character to String instead of <String,String>.