class Test {

    String use(String[] list) {
    for(String str : list) {
        String s = str;
        if (s == null) break;
        s = s.trim();
        if (s.isEmpty()) break;
        int i;
        try {
          i = Integer.parseInt(s);
        }
        catch (NumberFormatException ex) {
            break;
        }
        if (i <= 0) {
            break;
        }
        System.out.println("Ok string: "+str);
    }
  }
}