How to implement Java single Database thread

Question

I have made a Java program that connects to a SQLite database using SQLite4Java.

I read from the serial port and write values to the database. This worked fine in the beginning, but now my program has grown and I have several threads. I have tried to handle that with a SQLiteQueue-variable that execute database operations with something like this:

public void insertTempValue(final SQLiteStatement stmt, final long logTime, final double tempValue)
{
    if(checkQueue("insertTempValue(SQLiteStatement, long, double)", "Queue is not running!", false))
    {
        queue.execute(new SQLiteJob<Object>()
                {
                    protected Object job(SQLiteConnection connection) throws SQLiteException
                    {
                        stmt.bind(1, logTime);
                        stmt.bind(2, tempValue);

                        stmt.step();
                        stmt.reset(true);

                        return null;
                    }
                });
    }
} // end insertTempValue(SQLiteStatement, long, double)

But now my SQLite-class can't execute the statements reporting :

DB[1][U]: disposing [INSERT INTO Temperatures VALUES (?,?)]DB[1][U] from alien thread
SQLiteDB$6@8afbefd: job exception com.almworks.sqlite4java.SQLiteException: [-92] statement is disposed

So the execution does not happen.

I have tried to figure out what's wrong and I think I need a Java wrapper that makes all the database operations calls from a single thread that the other threads go through.

Here is my problem I don't know how to implement this in a good way. How can I make a method-call and ensure that it always runs from the same thread?

Answer 1

I found a solution to my problem. I have now implemented a wrapper-class that makes all operations with my older SQLite-class using an ExecutorService, inspired from Thread Executor Example and got the correct usage from Java Doc ExecutorService.