java.sql.SQLException: database connection closed

Question

I have a problem with the SQLite driver for Java (JDBC). When I want to load a database, it says that it was loaded, but instatly it was closed. I seperated my code in different files:

SQLite.java

package net.jeddsan;

import java.sql.Connection;
import java.sql.DatabaseMetaData;
import java.sql.DriverManager;
import java.sql.SQLException;

public class SQLite {
    public static Connection createOrOpenDatabase(String database) {

        String url = "jdbc:sqlite:" + database;

        try (Connection conn = DriverManager.getConnection(url)) {
            if (conn != null) {
                System.out.println("A new database has been created.");
                conn.setAutoCommit(false);
                return conn;
            }else{
                return null;
            }

        } catch (SQLException e) {
            System.out.println(e.getMessage());
            return null;
        }
    }
}

MainController.java

@Override
    public void initialize(URL url, ResourceBundle rb) {
        c = SQLite.createOrOpenDatabase("test.db");

        try {
            sta = c.createStatement();
            sta.executeQuery("INSERT INTO token (token) VALUES ('123')");
            sta.close();
        } catch (SQLException ex) {
            Logger.getLogger(MainController.class.getName()).log(Level.SEVERE, null, ex);
        }
        try {
            c.close();
        } catch (SQLException ex) {
            Logger.getLogger(MainController.class.getName()).log(Level.SEVERE, null, ex);
        }
    }

Log

SCHWERWIEGEND: null
java.sql.SQLException: database connection closed
    at org.sqlite.core.CoreConnection.checkOpen(CoreConnection.java:336)
    at org.sqlite.jdbc4.JDBC4Connection.createStatement(JDBC4Connection.java:38)
    at org.sqlite.jdbc3.JDBC3Connection.createStatement(JDBC3Connection.java:193)
    at net.jeddsan.MainController.initialize(MainController.java:103)
    at javafx.fxml.FXMLLoader.loadImpl(FXMLLoader.java:2548)
    at javafx.fxml.FXMLLoader.loadImpl(FXMLLoader.java:2441)
    at javafx.fxml.FXMLLoader.loadImpl(FXMLLoader.java:3214)
    at javafx.fxml.FXMLLoader.loadImpl(FXMLLoader.java:3175)
    at javafx.fxml.FXMLLoader.loadImpl(FXMLLoader.java:3148)
    at javafx.fxml.FXMLLoader.loadImpl(FXMLLoader.java:3124)
    at javafx.fxml.FXMLLoader.loadImpl(FXMLLoader.java:3104)
    at javafx.fxml.FXMLLoader.load(FXMLLoader.java:3097)
    at net.jeddsan.koradesktop.start(koradesktop.java:22)
    at com.sun.javafx.application.LauncherImpl.lambda$launchApplication1$162(LauncherImpl.java:863)
    at com.sun.javafx.application.PlatformImpl.lambda$runAndWait$175(PlatformImpl.java:326)
    at com.sun.javafx.application.PlatformImpl.lambda$null$173(PlatformImpl.java:295)
    at java.security.AccessController.doPrivileged(Native Method)
    at com.sun.javafx.application.PlatformImpl.lambda$runLater$174(PlatformImpl.java:294)
    at com.sun.glass.ui.InvokeLaterDispatcher$Future.run(InvokeLaterDispatcher.java:95)
    at com.sun.glass.ui.win.WinApplication._runLoop(Native Method)
    at com.sun.glass.ui.win.WinApplication.lambda$null$148(WinApplication.java:191)
    at java.lang.Thread.run(Thread.java:745)

Not related to your problem, but some advice: in your initialize method, don't assign the connection to an instance field, but to a local variable, and use a try-with-resources instead of a handwritten finally-block with a close(). Using an instance field for the connection will only give you pain the long run. — Mark Rotteveel
– Mark Rotteveel, Commented Feb 27, 2017 at 19:43

hoaz · Accepted Answer · 2017-02-27 19:33:07Z

15

This try-with-resources construct will invoke method close on Connection when you leave its scope:

try (Connection conn = DriverManager.getConnection(url)) {
    return conn;
}

So, you effectively return closed connection.

Change it to regular try construct to return live connection:

try {
    Connection conn = DriverManager.getConnection(url);
    return conn;
} catch (SQLException e) {
    return null;
}

answered Feb 27, 2017 at 19:33

hoaz

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2 Comments

Julian Over a year ago

Thank you very much. That was the solution.

Mark Rotteveel Over a year ago

It would probably be better to remove the try-catch entirely and just add throws SQLException to the method. That will save you from unclear NullPointerExceptions, and you will need to handle SQLException anyway when executing queries on that connection.

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