code: public static boolean isAlphanumericSpace(final CharSequence cs) {
          if (N.isNullOrEmpty(cs)) {
              return false;
          }
  
          final int len = cs.length();
  
          if (cs.getClass().equals(String.class)) {
              final char[] chars = getCharsForReadOnly((String) cs);
  
              for (int i = 0; i < len; i++) {
                  if (Character.isLetterOrDigit(chars[i]) == false && chars[i] != ' ') {
                      return false;
                  }
              }
          } else {
              for (int i = 0; i < len; i++) {
                  if (Character.isLetterOrDigit(cs.charAt(i)) == false && cs.charAt(i) != ' ') {
                      return false;
                  }
              }
          }
  
          return true;
      }
docs: <p>
  Checks if the CharSequence contains only Unicode letters, digits or space
  ({@code ' '}).
  </p>
  
  <p>
  {@code null} or empty CharSequence (length()=0) will return {@code false}
  .
  </p>
  
  <pre>
  N.isAlphanumericSpace(null)   = false
  N.isAlphanumericSpace("")     = false
  N.isAlphanumericSpace("  ")   = true
  N.isAlphanumericSpace("abc")  = true
  N.isAlphanumericSpace("ab c") = true
  N.isAlphanumericSpace("ab2c") = true
  N.isAlphanumericSpace("ab-c") = false
  </pre>
  
  @param cs
  the CharSequence to check, may be null
  @return {@code true} if only contains letters, digits or space, and is
  non-null
  @since 3.0 Changed signature from isAlphanumericSpace(String) to
  isAlphanumericSpace(CharSequence)