generating id for a row
<p>i have called the return values nextId on a button click event but whenever i am trying to execute the button click event it initialses it to start and then it generates next can you please help me with this??</p>

<pre><code>package util;

import java.sql.Connection;
import java.sql.ResultSet;
import java.text.SimpleDateFormat;
import java.util.Date;

public class CalendarUtil {

    private static String buffer = "";
    private static int counter = 1;

    public String nextID() {
        final String datePrefix = new SimpleDateFormat("yyyyMMdd").format(new Date());

        if (Long.parseLong(returnMaxId()) &gt; 0) {
            CalendarUtil.counter = Integer.parseInt(returnMaxId().substring(8, returnMaxId().length()));
        }

        if (buffer.equals(datePrefix)) {
            CalendarUtil.counter++;
        } else {
            CalendarUtil.buffer = datePrefix;
            CalendarUtil.counter = 1;
        }

        String suffix = "";

        if (CalendarUtil.counter &lt;= 1000) {

            if (validateRange(0, 9, CalendarUtil.counter)) {
                suffix += "00" + counter;
            } else if (validateRange(10, 99, CalendarUtil.counter)) {
                suffix += "0" + counter;
            } else if (validateRange(99, 999, CalendarUtil.counter)) {
                suffix += counter;
            }
        }

        return (datePrefix + suffix);
    }

    public boolean validateRange(int min, int max, int field) {
        return field &gt;= min &amp;&amp; field &lt;= max;
    }

    public String returnMaxId() {
        String result = "";
        try {
            DBUtil util = new DBUtil();
            Connection connection = util.getConnection();
            ResultSet rs = connection.createStatement().executeQuery("SELECT MAX(id) AS 'lastId' FROM crap ");
            if (rs.next()) {
                result = (rs.getString(1) != null) ? rs.getString(1) : "0";
            }
        } catch (Exception e) {
            e.printStackTrace();
            System.out.println("Error : " + e.getMessage());
        }
        return result;
    }
    public static void main(String[] args) {

    }
}
</code></pre>
