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Using resultset data after closing the connection

I'm trying to write a small code snippet where I need to get some data from a database and then process the result in some other java file. I tried writing a program and the execution for the same was failing with error "Cannot access resultset as the connection was already closed".
Is there any way can we store the result fetched from database some where (Ex.some arraylist) and use it for computation after closing the connection? If yes, can someone please explain it with example?
Slightly handicapped since I'm new to it.
Class A {
public Map<String, Object> loadDat(int acc,Map<String,Object> result)
throws Exception {
Class.forName("com.teradata.jdbc.TeraDriver");
Connection conn = DriverManager.getConnection(connectionString, user, password);
query = "select * from mytable where id="+acc;
PreparedStatement stmt = conn.prepareStatement(query);
ResultSet rs=stmt.executeQuery();
result.put(" Result", rs) ;
return result;
}
}

In general,
don't code JDBC database access by hand.
Libraries already exist that do all the low level JDBC handling now and
they do it correctly.
You will never do it better than an one of the mature,
open source projects already do it.
Instead,
learn and use something like MyBatis.
If you use Spring,
here is a link to the Mybatis-Spring project.
MyBatis conceals all of the data conversion and JDBC junk.
Instead, you define your query in a simple XML file and receive a List
as the result of a query.

Just to add to #DwB's answer that is correct.
You can 1) retrieve all rows from your query into a Java List, 2) then close the connection, and 3) then use the Java List in another class (for further processing).
If you close the connection after retrieving only part of the result set, you'll lose the rest of it and will receive the error you mention. Don't do it this way.

Why is my executeQuery hanging up?

I'm running what would seem as an otherwise simple piece of code. On its simplified form, it looks like this:
public class ReadDB throws SQLException {
private Connection conn;
private PreparedStatement myStmt;
public ReadDB(Connection connection) {
conn = connection;
}
public List<GameEvent> getEvents(int gameId) {
List<GameEvent> ret = new ArrayList<GameEvent>();
myStmt = conn.prepareStatement("select * from logs where gameid=? order by id");
myStmt.setInt(1, gameId);
myStmt.setQueryTimeout(10); // Wasn't there before, doesn't really help
ResultSet rs = myStmt.executeQuery();
while( rs.next() ) {
// Do stuff, using "rs.getString()"
}
rs.close();
myStmt.close()
return ret;
}
}
And this is what the database initialization looks like (the connection parameter):
String url=“jdbc:mysql://server.example.com/database_name”;
cProperties = new Properties();
cProperties.put(“user”, user);
cProperties.put(“password”, password);
// truncate field values that are too long
cProperties.put(“jdbcCompliantTruncation”, “false”);
connection=DriverManager.getConnection(url,cProperties);
Now, my problem is: after calling the getEvents method several times (around 30), executeQuery() will just hang. No exception, no return value, nothing - it just stops there, probably in some kind of loop.
The database is read only, so there are no INSERT of any kind. Connecting to the (MySQL) database, show processlist lists the connection as Sleep while the connection time goes up. Of course, I can run the query just fine in a parallel window, but the Java program for some reason cannot. Also, it always hangs in a different gameId, so it's not related to that particular set.
Given that a very similar piece of code used to run just fine, I'm guessing that either I'm not opening/closing the connection the right way, or a network-related problem.
Ideas, anyone?
Edit: I updated the code according to address some of the comments, still with no positive results. Regarding debugging, the code seems to be stuck at the deepest level in
n = socketRead0(fd, b, off, length, timeout);
inside the read() function from java.net.SocketInputStream. The trace would be: an instance of java.sql.PreparedStatement (the one in the code) calls executeQuery, which calls executeInternal, which calls several MysqlIO functions, the deepest of which is MysqlIO.readFully (called by MysqlIO.nextRowFast). I can't peek inside this functions, but I can see them being called. I suspect, however, that this is too much detail, and that the error must be somewhere else.

I have also faced similar issue. The program actually stops and waits at the executeQuery() command.
But my issue gets resolved when I do the following :
Commit my Oracle Database after I deleted the Table directly from Oracle
Client(Toad).

How to enter SQL instruction in controller with play 2 and java

I'm developing a web application with Play 2.1.0 and programming it with Java and I need to have access to data already saved in a DB to modify them.
I tried to create a new instance without the new operator and reference it to my object saved in the database, but even if there is no pointer error, it won't change values of attributes. I couldn't figure out why, so I've decided to enter SQL queries directly.
Same thing, it does not seems to have any mistake, but it won't change anything... I think this comes from a bad link to the database :
Here is my code in application.java :
public static Result modifyQuestionnaire(Long id) throws SQLException {
Statement stmt = null;
Connection con = DB.getConnection();
try {
stmt = con.createStatement(ResultSet.TYPE_SCROLL_SENSITIVE, ResultSet.CONCUR_UPDATABLE);
String query = "SELECT * FROM WOQ.questionnaire WHERE id=id";
ResultSet uprs = stmt.executeQuery(query);
uprs.updateString("name", "baba");
uprs.updateRow();
} catch(Exception e) {
e.printStackTrace();
} finally {
if (stmt!=null) {
stmt.close();
}
}
return redirect(routes.Application.questionnaire(id));
}
And I also try to enter an UPDATE query directly, still the same..
I've looked everywhere and did not find any solution (except Anorm but it seems to work with Scala language)
Btw, if anyone knows a solution with a second instance that refers to the same object (it seems possible but as I say, there is no error but no actions neither), it's fine for me.

Huh, you showed as that you are trying to create totally new connection, so I supposed, that you don't want to use Ebean, but in case when you are already use it, you can just use its methods for the task:
(copied) There are some options in Ebean's API, so you should check it and choose one:
Update<T> - check in the sample for #NamedUpdates annotation
Ebean.createUpdate(beanType, updStatement)
SqlUpdate - you can just perform raw SQL update, without need for giving the entity type

Why Java MySQL connection can't detect change that made by trigger?

I have a problem and need some enlightenment here..
I am using trigger to detect change made to my database, means that I set all my table with trigger for insert, update, and delete (MySQL)
Then I write that change into a table that I have made specifically to contain all information about the change. Let's name it xtable. (This table is not equipped with trigger)
My Java program need to continuously read that xtable to let other application know about the change.
Well the problem is, when I read the xtable in a loop, I can only read the initial value of the xtable that is when I established the connection to the database. (connection is established outside the loop)
If a change has been made to the database which will lead to new row in xtable, this new row which is produced by the trigger is not detected no matter how many times I read it with executing "select * from xtable" query..
The code look like this:
public static void main(String[] args) {
Connection conn = null;
try {
conn = database.getConnection();
Statement state = conn.createStatement();
String query = "select * from `xtable`;";
while (true) {
ResultSet rs = state.executeQuery(query);
while(rs.next){
// Some code for letting the other application know of the change
}
}
} catch (SQLException ex) {
} finally {
if (conn != null) {
conn.close();
}
}
}
So basically if I run the program while the xtable is empty, I always gain an empty ResultSet even when there is a new row after sometimes.
Actually this problem can be solved by established the connection inside the loop, but then it will lead to another problem because it will consume more and more resource as the loop go around. (I have already try this and it will eventually use all resource on my computer after sometimes even when I have already properly closed it)
So can anyone please give me some suggestion what to do?
This is my first time posting a question here, I am sorry if there is some rule that I don't follow and please give me the right direction.

Thereis such thing as transaction isolation. It could be possible that your connection does not see changes because you did not commited transaction coming from trigger, or you did not started new one on client side. Impossible to tell without seeing your database set up.
PS: Message queuing is way better alternative

I think you'd better consider trigger instead of querying to the DBMS by looping.
If you use trigger you don't have to use that 'while' loop from Java side to check the change of DB.
Instead, trigger mechanism which is embedded in the DBMS will notify the Java side when the change happens.
For Oracle, you can call Java method from PL/SQL.
For PostgreSQL, you can call Java method from PL/Java.
For CUBRID, you can call Java method from Java stored procedure.
For MySQL, you can call Java method but I don't think it is as easy as above.
I wish this link would help you out. http://code.rocksol.it/call-java-from-mysql-trigger
Or google this keyword, "mysql java user defined functions"

Connection connection=getConnection();
statement="query";
try {
stmt = connection.prepareStatement(statement);
ResultSet rs = stmt.executeQuery();
while (rs.next()) {
}
} catch (SQLException e) {
e.printStackTrace();
} finally {
if (connection != null && stmt != null) {
stmt.close();
}
}

Mysql read data immediately after writing?

I am using a MySQL DB and a Java JDBC client to access it.
I have a Table that contains session information. Each session is associated with a SessionToken. This token is a Base64 encoded String of a Hash of some of the session values. It should be unique. And is defined as varchar(50) in the db.
When I try to lookup a session by its token I query the database using an sql statement like this:
select SessionId, ClientIP, PersonId, LastAccessTime, SessionCreateTime from InkaSession where SessionToken like 'exK/Xw0imW/qOtN39uw5bddeeMg='
I have a UnitTest that tests this functionality, and it consistently fails, because the query does not return any Session, even tough, I have just written the session to the DB.
My Unit test does the following:
Create Connection via DriverManager.getConnection
Add a session via Sql Insert query
close the connection
create Connection via DriverManager.getConnection
look for the session via sql select
unit test fails, because nothing found
When I step through this UnitTest with the debugger and copy past the select sql that is about to be sent to the db into a mysql command line, it works fine, and I get the session row back.
I also tried to retrive an older session from the db by asking for an older SessionToken. This works fine as well. It only fails, if I ask for the SessionToken immediately after I inserted it.
All connections are on AutoCommit. Nevertheless I tried to set the Transaction Level to "Read Uncommited". This did not work either.
Has anyone any further suggestions?

This is typically caused by the connection not being committed between insert and select.
Did you basically do the following?
statement.executeUpdate("INSERT INTO session (...) VALUES (...)");
connection.commit();
resultSet = statement.executeQuery("SELECT ... FROM session WHERE ...");
Edit I tried the following SSCCE on MySQL 5.1.30 with Connector/J 5.1.7:
public static void main(String[] args) throws Exception {
Class.forName("com.mysql.jdbc.Driver");
Connection connection = null;
Statement statement = null;
ResultSet resultSet = null;
try {
connection = DriverManager.getConnection("jdbc:mysql://localhost/javabase", "root", null);
statement = connection.createStatement();
statement.executeUpdate("INSERT INTO foo (foo) VALUES ('foo')");
resultSet = statement.executeQuery("SELECT id FROM foo WHERE foo = 'foo'");
if (resultSet.next()) {
System.out.println(resultSet.getLong("id"));
} else {
System.out.println("Not inserted?");
}
} finally {
SQLUtil.close(connection, statement, resultSet);
}
}
Works flawlessly. Maybe an issue with your JDBC driver. Try upgrading.

Solved: The two token strings where not identical. One of them had a couple of Zero bytes at the end. (Due to the encrypting and decrypting and padding...) The two strings where visually identical, but MySQL and Java both said, they where not. (And they where right as usual)