Julian Schmuckli Julian Schmuckli -4 years ago 263
Java Question

java.sql.SQLException: database connection closed

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)

Answer Source

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;
}
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