jodd-core/src/main/java/jodd/util/StringUtil.java
public static String replaceChar(final String s, final char sub, final char with) {
		int startIndex = s.indexOf(sub);
		if (startIndex == -1) {
			return s;
		}
		char[] str = s.toCharArray();
		for (int i = startIndex; i < str.length; i++) {
			if (str[i] == sub) {
				str[i] = with;
			}
		}
		return new String(str);
	}
public static String replaceChar(final String s, final char sub, final char with) {
		int startIndex = s.indexOf(sub);
		if (startIndex == -1) {
			return s;
		}
		char[] str = s.toCharArray();
		for (int i = startIndex; i < str.length; i++) {
			if (str[i] == sub) {
				str[i] = with;
			}
		}
		return new String(str);
	}
Replaces all occurrences of a character in a string.

@param s      input string
@param sub    character to replace
@param with   character to replace with