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Java Forum / General / March 2007Please, I am going insane: First element access causing ArrayIndexOutOfBoundsException:0
Hello there, Please God can someone help me before I break my PC. I have a class that runs a query against an Oracle 10g database. The query is returning the results I want. I get two users which is what I want. I have an array created that has a length of two. I feed the results of the query into the array... <code> int[] engineers = new int[2]; String sql = "select USERID from g_user where role='Engineer'"; PreparedStatement pstmt = tempConn.prepareStatement(sql); ResultSet rs = pstmt.executeQuery(); while (rs.next()) { engineers[i] = rs.getInt("USERID"); // find result of count i++; } </code> The very next thing if i try <code> System.out.println("engineer array length is " + engineers.length); System.out.println("engineer array 0 is " + engineers[0]); System.out.println("engineer array 1 is " + engineers[1]); </code> I get.... <code> engineer array length is 2 java.lang.ArrayIndexOutOfBoundsException: 0 engineer array 0 length is 85 engineer array 1 length is 123 </code> If i take out the first print message to find the length i get the same error when i try to access the first element. If i take out the message to access the length and the first element i get no error whatsoever! but obviously i cannot do anything useful with my program because i cannot access the first element. I thought i was losing my mind, so i created a tiny program with just this code on its own and it runs perfectly which is making me even crazier! What in the name of all that is good could be causing this?! I mean it is printing out the correct contents and length of the array even after it shows an error to say outofbounds! Any help at all is very much appreciated... Thank you, J. > Hello there, > [quoted text clipped - 43 lines] > is printing out the correct contents and length of the array even > after it shows an error to say outofbounds! A few things: There's a slight disconnect between the code you say you're executing and the output you're getting, so either you just typed it into this message wrong, or you're not executing the code you think you are. For instance, you reference a code line of this: System.out.println("engineer array 0 is " + engineers[0]); and an output line of this: engineer array 0 length is 85 In the code, you don't say "length", but it's in the output. Again, this could be a trivial error in the input of this message, or it could be telling. Figure that out. Second, you don't see the stack trace from that exception, so it's hard to tell for certain where it's coming from. You could wrap all of your code in a specific try/catch for that exception and print out the stack trace. That might give you more information. If you add that code, and the output doesn't change at all, then somehow that exception is happening somewhere else entirely. Third, if you say you've extracted this code into an isolated test case, and it doesn't demonstrate the problem, then what are you doing differently? Is the code that creates and populates the "engineers" list really right before the code that prints out the values, or are they perhaps in two different scopes (or threads?) where the "engineers" list isn't populated yet? homerjk wrote On 03/08/07 14:53,: > Hello there, > [quoted text clipped - 43 lines] > is printing out the correct contents and length of the array even > after it shows an error to say outofbounds! No, it's not. The final two lines of output must be coming from somewhere else altogether, for two reasons: First, when the exception is thrown (from whereever it is thrown) the normal flow of control in your code is broken off and execution resumes in a catch clause somewhere further up the stack. This means your second and third println() calls never execute at all (or if the exception is thrown while constructing the String to be printed by the first, that call is aborted and produces no output). Either way, none of the output comes from the second two println()s. Second, another and perhaps easier way to see that the second two println()s don't produce the output is to note that the output contains the substring "length " which the println() calls do not generate. The output comes from some entirely different piece of code. Since the mysterious output comes from something you haven't revealed, I'm at a loss to explain it.  SignatureEric.Sosman@sun.com > No, it's not. The final two lines of output must > be coming from somewhere else altogether, for two reasons: [quoted text clipped - 19 lines] > -- > Eric.Sos...@sun.com Hi Guys, Thanks for the replies. Apologies for the mix up over what was being printed out, I typed that out myself and just copied the first statement and pasted it out the other two times and changed it to have the right output. Its sorted now anyway. I re-wrote the whole thing from scratch and I think the problem may have been coming from the use/re-use of the prepared statements and resultsets. I gave each section its own prepared statement and resultset and they problem now does not occur at all. Still not too sure why though as before hand I was clearing out the prepared statements each time... Regardless, it is working now and I will be able to sleep tonight! Thank you for you suggestions, J. > homerjk wrote On 03/08/07 14:53,: > [quoted text clipped - 69 lines] > -- > Eric.Sos...@sun.com Guys, thanks for your replies, I wrote a long winded reply but it got lost somewhere along the way. Apologies for the confusion over the println's, this was a mistake, I typed these out myself and this was not the actual program output. The problem is now fixed, I re-wrote the program from scratch and I suspect the problem was coming from the use/re-use of the prepared statements and resultsets. On re-writing the code I gave each section its own prepared statement and resultset and it fixed the problem. I'm still not 100% sure as to why this was causing the problem as I was clearing out the prepared statements before re-using them. Regardless, the program is working now and I will be able to sleep tonight. Thank you, J. Free MagazinesGet these publications absolutely FREE for up to 12 months. There are no hidden fees and no obligation. Simply choose a title, complete the application form and submit it. Read more ...
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