code: public static boolean isAsciiPrintable(String str) {
          if (str == null) {
              return false;
          }
          int sz = str.length();
          for (int i = 0; i < sz; i++) {
              if (CharUtils.isAsciiPrintable(str.charAt(i)) == false) {
                  return false;
              }
          }
          return true;
      }
docs: <p>Checks if the string contains only ASCII printable characters.</p>
  
  <p><code>null</code> will return <code>false</code>.
  An empty String (length()=0) will return <code>true</code>.</p>
  
  <pre>
  StringUtils.isAsciiPrintable(null)     = false
  StringUtils.isAsciiPrintable("")       = true
  StringUtils.isAsciiPrintable(" ")      = true
  StringUtils.isAsciiPrintable("Ceki")   = true
  StringUtils.isAsciiPrintable("ab2c")   = true
  StringUtils.isAsciiPrintable("!ab-c~") = true
  StringUtils.isAsciiPrintable("\u0020") = true
  StringUtils.isAsciiPrintable("\u0021") = true
  StringUtils.isAsciiPrintable("\u007e") = true
  StringUtils.isAsciiPrintable("\u007f") = false
  StringUtils.isAsciiPrintable("Ceki G\u00fclc\u00fc") = false
  </pre>
  
  @param str the string to check, may be null
  @return <code>true</code> if every character is in the range
  32 thru 126
  @since 2.1