public static String toString(char ch) {
        if (ch < 128) {
            return CHAR_STRING_ARRAY[ch];
        }
        return new String(new char[] {ch});
    }
<p>Converts the character to a String that contains the one character.</p>

<p>For ASCII 7 bit characters, this uses a cache that will return the
same String object each time.</p>

<pre>
  CharUtils.toString(' ')  = " "
  CharUtils.toString('A')  = "A"
</pre>

@param ch  the character to convert
@return a String containing the one specified character
android/android_framework/base/src/main/java/lang3/CharUtils.java