caesar cipher java
public static String incode(String strIn, int delta) {
String strOut = "";
// bring delta to positive value
while (delta < 0) {
delta += 26;
}
for (int i = 0; i < strIn.length(); i++) {
char c = strIn.charAt(i);
if (Character.isAlphabetic(c)) {
char startLetter = Character.isUpperCase(c) ? 'A' : 'a'; // convert [a, z] to [0, 25]
strOut += (char) ((c - startLetter + delta) % 26 + startLetter);
} else {
strOut += c;
}
}
return strOut;
}
public static String decode(String strIn, int delta) {
return incode(strIn, -delta);
}