code: public static boolean isNumericSpace(String str) {
        if (str == null) {
            return false;
        }
        int sz = str.length();
        for (int i = 0; i < sz; i++) {
            if ((Character.isDigit(str.charAt(i)) == false) && (str.charAt(i) != ' ')) {
                return false;
            }
        }
        return true;
    }
docs: <p>Checks if the String contains only unicode digits or space
  (<code>' '</code>).
  A decimal point is not a unicode digit and returns false.</p>
  
  <p><code>null</code> will return <code>false</code>.
  An empty String ("") will return <code>true</code>.</p>
  
  <pre>
  GosuStringUtil.isNumeric(null)   = false
  GosuStringUtil.isNumeric("")     = true
  GosuStringUtil.isNumeric("  ")   = true
  GosuStringUtil.isNumeric("123")  = true
  GosuStringUtil.isNumeric("12 3") = true
  GosuStringUtil.isNumeric("ab2c") = false
  GosuStringUtil.isNumeric("12-3") = false
  GosuStringUtil.isNumeric("12.3") = false
  </pre>
  
  @param str  the String to check, may be null
  @return <code>true</code> if only contains digits or space,
  and is non-null