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POHow to avoid setting variable in a try statement
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  1. POHow to avoid setting variable in a try statement
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    copied!<p>My problem is that I have to set a variable in a try statement otherwise I get a compile error.</p> <p>Later on I need to use that variable but it is now out of scope, or so I believe. I initialise the variable outside the try statement and set it to null, I thought that it might then be accessible outside, but I still get a <code>NullPointerException</code>.</p> <p>The code is below, with lots of it taken out to make reading easier - I know it's bad code, but I am new to Servlets and just wanted to see it running with all the moving parts doing what they are supposed to.</p> <p>I have created another class that calls createDocs(...) and passes in the required parameters, and it works fine. So that is making me curious as to why when I call <code>rs.getString("name")</code> I get the <code>NullPointerException</code>, as this is exactly what I do from the other class (run from a main method for convenience) and it works as expected.</p> <p>The variable in question is the ResultSet variable "rs" -</p> <pre><code>public class AgReportServlet extends HttpServlet { private static final long serialVersionUID = 1L; public AgReportServlet() { super(); } public void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { ResultSet rs = null; try { rs = docs.getDocs(con, start, end, zone, locality); } catch (SQLException e) { // TODO Auto-generated catch block e.printStackTrace(); } catch (InstantiationException e) { // TODO Auto-generated catch block e.printStackTrace(); } catch (IllegalAccessException e) { // TODO Auto-generated catch block e.printStackTrace(); } catch (ClassNotFoundException e) { // TODO Auto-generated catch block e.printStackTrace(); } response.setContentType("text/xml"); PrintWriter out = response.getWriter(); out.println("&lt;!DOCTYPE html PUBLIC \"-//W3C//DTD XHTML 1.0 Transitional//EN\" \"http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd\"&gt;\n" + out.println( "&lt;table border=\"0\" cellspacing=\"0\" cellpadding=\"6\"&gt;\n"); // I have a resultset object need to iterate through it to display the file names try { while (rs.next()) { // page through the result set out.println( " &lt;tr&gt;\n" + " &lt;td&gt;: " + rs.getString("name") + "&lt;/td&gt;\n" + " &lt;/tr&gt;\n" ); } } catch (SQLException e) { // TODO Auto-generated catch block e.printStackTrace(); } out.println( "&lt;/table&gt;&lt;/body&gt;\n" + "&lt;/html&gt;" ); out.flush(); out.close(); } } </code></pre>
 

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