Warning: java.lang.IndexOutOfBoundsException

Question

when calling the following function I get an error. The HQL query functions downloading data from the database, but unfortunately I get an error:

java.lang.IndexOutOfBoundsException: Index: 1, Size: 0
    at java.util.ArrayList.RangeCheck(Unknown Source)
    at java.util.ArrayList.get(Unknown Source)
    at com.example.server.RaportGenerator.checkParam(RaportGenerator.java:103)
    at com.example.server.RaportGenerator.doGet(RaportGenerator.java:58)
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:617)
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:717)
    at org.mortbay.jetty.servlet.ServletHolder.handle(ServletHolder.java:487)
    at org.mortbay.jetty.servlet.ServletHandler.handle(ServletHandler.java:362)
    at org.mortbay.jetty.security.SecurityHandler.handle(SecurityHandler.java:216)
    at org.mortbay.jetty.servlet.SessionHandler.handle(SessionHandler.java:181)
    at org.mortbay.jetty.handler.ContextHandler.handle(ContextHandler.java:729)
    at org.mortbay.jetty.webapp.WebAppContext.handle(WebAppContext.java:405)
    at org.mortbay.jetty.handler.HandlerWrapper.handle(HandlerWrapper.java:152)
    at org.mortbay.jetty.handler.RequestLogHandler.handle(RequestLogHandler.java:49)
    at org.mortbay.jetty.handler.HandlerWrapper.handle(HandlerWrapper.java:152)
    at org.mortbay.jetty.Server.handle(Server.java:324)
    at org.mortbay.jetty.HttpConnection.handleRequest(HttpConnection.java:505)
    at org.mortbay.jetty.HttpConnection$RequestHandler.headerComplete(HttpConnection.java:829)
    at org.mortbay.jetty.HttpParser.parseNext(HttpParser.java:513)
    at org.mortbay.jetty.HttpParser.parseAvailable(HttpParser.java:211)
    at org.mortbay.jetty.HttpConnection.handle(HttpConnection.java:380)
    at org.mortbay.io.nio.SelectChannelEndPoint.run(SelectChannelEndPoint.java:395)
    at org.mortbay.thread.QueuedThreadPool$PoolThread.run(QueuedThreadPool.java:488)

And this is my function:

protected boolean checkParam(String login, String sid) {
    boolean result = false;
    List listOfData;
    try {
        Session session = HibernateUtil.getSessionFactory().openSession();
        Query query = session.createQuery("Select u.login, u.sid from User u Where u.login = :login");
        query.setParameter("login",login);
        listOfData = query.list();
        String sidDb = listOfData.get(1).toString();
        if (sid == sidDb) {
            result = true;  
        }
        session.close();
    } catch (HibernateException e) {
        e.printStackTrace();
    }
    return result;
}

RaportGenerator.java:103 is:


String sidDb = listOfData.get(1).toString();

Answer 1

There are multiple things wrong with this code:

• You're asking for element 1, which is the second element. I suspect you actually meant get(0) to get the first element.
• That will still fail if the user's login doesn't exist, of course... you should use listOfData.size() first to check.
• You don't need the result variable - just return when you know the answer.
• The listOfData variable can be declared in a tighter scope, which is generally good practice.
• You should probably be closing the session in a finally block, from what I remember.
• You shouldn't be testing string equality with == .
• You probably shouldn't be catching HibernateException at this point in your code, and even if you do , you should probably use a better logging mechanism.

Here's a code sample with most of this cleaned up.

protected boolean checkParam(String login, String sid) {
    Session session = null;
    try {
        session = HibernateUtil.getSessionFactory().openSession();
        Query query = session.createQuery
            ("Select u.login, u.sid from User u Where u.login = :login");
        query.setParameter("login",login);
        List listOfData = query.list();
        return listOfData.size() == 1 
               && listOfData.get(0).toString().equals(sidDb);
    } catch (HibernateException e) {
        // Do you really just want to print the stack trace to stdout?
        // I would probably change the method to allow the exception
        // to bubble up...
        e.printStackTrace();
    } finally {
        if (session != null) {
            session.close();
        }
    }
}

Answer 2

You should check the size of listOfData before trying to get the first item. In this case your query is returning 0 or 1 result. If you mean to get the first item you should change to get(0) . Regardless you should code to handle the query returning nothing.

It looks like you also have a mistake in how you are comparing the result.

        String sidDb = listOfData.get(1).toString();
        if (sid == sidDb) {
            result = true;  
        }

Should be changed to.

     String sidDb = listOfData.get(0).getSid()
     if (sid.equals(sidDb)) {
         result = true;  
     }

Answer 3

Your query is not returning any rows from the database, therefore listofData does not contain any objects and its length =0 . When you make the call to

String sidDb = listOfData.get(1).toString();

Your asking the array to return an object that does not exist, therefore there is no index for the object in the array.