How to handle error number format exception :For input string: “”

Question

I'm doing a simple insert in one form.

1. no_text & no_text_external were choose from drop down
2. I'm saving the id for no_text & no_text_external in another table which is

dbname_m_db

and would like to view it back. So i'm doing 4 test which are

test1: insert no_text

test2: insert no_text_external

test3: insert no_text & no_text_external

test4: not insert both

so the result is, only test3 is success to view it back. while the other 3 return error number format exception :For input string: "" . I don't know the best way to filter it. Here the code that im working for. Any idea?

    public void getDataById(Connection con){

    try{
        ps = con.createStatement();

        rs = ps.executeQuery("SELECT * FROM "+ dbname_m_db +" WHERE id_m_db ='"+ this.getId_m_db() +"' AND status_data ='1'");

        while (rs.next()) {
            this.setNo_text(rs.getString("no_text"));
            this.setNo_text_external(rs.getString("no_text_external"));
        }
            int int_no_text = Integer.valueOf(this.getNo_text());
            int int_no_text_external = Integer.valueOf(this.getNo_text_external());
            this.setNo_text_value(au.getTextById(con, int_no_text));
            this.setNo_text_external_value(au.getTextExternalById(con, int_no_text_external));

    } catch (Exception e) {
        throw new RuntimeException(e);
    }
}

Answer 1

In order to handle the NumberFormatException error, you should validate your String before executing Integer.valueOf() .

You could validate if your string is empty:

int int_no_text;

if (!this.getNo_text().isEmpty) {
    int_no_text = Integer.valueOf(this.getNo_text());
}

Honestly, I'm not really fond of this approach because one is neither validating if the string is null or if it contains, in fact, an integer.

Therefore, one could make use of a really good utility class, NumberUtils , and validate if we're on a presence of a number:

int int_no_text;

if (NumberUtils.isNumber(this.getNo_text())) {
    int_no_text = Integer.valueOf(this.getNo_text());
}

Basically, this way one checks whether the string is a valid Java number hence null and empty/blank strings will return false.

Answer 2

It looks like you're passing an empty string when you are getting the integer value from the table. I would check to make sure that you're getting he expected return from the table before converting it into an int