code: public static boolean isPrintableChar(char ch) {
          if (ch >= 'a' && ch <= 'z') {
              return true;
          }
          if (ch >= 'A' && ch <= 'Z') {
              return true;
          }
          if (ch >= '0' && ch <= '9') {
              return true;
          }
  
          // loop thru our PRINTABLE string
          for (int i = 0; i < PRINTABLE.length(); i++) {
              if (ch == PRINTABLE.charAt(i)) {
                  return true;
              }
          }
  
          return false;
      }
docs: Return true if the character is printable in ASCII. Not using
  Character.isLetterOrDigit(); applies to all unicode ranges.