public static String replaceChars(String str, char searchChar, char replaceChar) {
        if (str == null) {
            return null;
        }
        return str.replace(searchChar, replaceChar);
    }
<p>Replaces all occurrences of a character in a String with another.
This is a null-safe version of {@link String#replace(char, char)}.</p>

<p>A {@code null} string input returns {@code null}.
An empty ("") string input returns an empty string.</p>

<pre>
StringUtils.replaceChars(null, *, *)        = null
StringUtils.replaceChars("", *, *)          = ""
StringUtils.replaceChars("abcba", 'b', 'y') = "aycya"
StringUtils.replaceChars("abcba", 'z', 'y') = "abcba"
</pre>

@param str  String to replace characters in, may be null
@param searchChar  the character to search for, may be null
@param replaceChar  the character to replace, may be null
@return modified String, {@code null} if null string input
@since 2.0
android/android_framework/base/src/main/java/lang3/StringUtils.java