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java.sql.SQLException: Access denied for user ''#'localhost' (using password: NO)

So I'm getting the error java.sql.SQLException: Access denied for user ''#'localhost' (using password: NO) when I try to connect to MySQL Database from Java code. Everything I was able to find didn't solve the Problem at all and the code is very basic. I used it in projects before and found it like that in many tutorials. So first the relevant code:
//Inside class that manages SQLConnection
public SQLTransceiver(String url){
this.connectionURL = url;
this.reconnect();
}
public void reconnect(){
try {
Connection connection = DriverManager.getConnection(this.connectionURL); //Where the error occurs
this.currentConnection = connection;
} catch (SQLException e) {
e.printStackTrace();
}
}
//Inside main class I call this for testing purpose
String s = "jdbc:mysql://localhost:3306/tableName" +
"?user=user" +
"&password=thePassword" +
"&serverTimezone=MET";
DataTransreciever transreciever = new SQLTransceiver(s);
NOTE: I can perfectly log into the DB in MySQL workbench and do everything there from creating/altering tables to inserting and all that stuff.
The whole Stacktrace looks like this:
java.sql.SQLException: Access denied for user ''#'localhost' (using password: NO)
at com.mysql.cj.jdbc.exceptions.SQLError.createSQLException(SQLError.java:129)
at com.mysql.cj.jdbc.exceptions.SQLError.createSQLException(SQLError.java:97)
at com.mysql.cj.jdbc.exceptions.SQLExceptionsMapping.translateException(SQLExceptionsMapping.java:122)
at com.mysql.cj.jdbc.ConnectionImpl.createNewIO(ConnectionImpl.java:836)
at com.mysql.cj.jdbc.ConnectionImpl.<init>(ConnectionImpl.java:456)
at com.mysql.cj.jdbc.ConnectionImpl.getInstance(ConnectionImpl.java:246)
at com.mysql.cj.jdbc.NonRegisteringDriver.connect(NonRegisteringDriver.java:197)
at java.sql.DriverManager.getConnection(DriverManager.java:664)
at java.sql.DriverManager.getConnection(DriverManager.java:208)
at main.data.SQLTransceiver.reconnect(SQLTransceiver.java:31)
at main.data.SQLTransceiver.<init>(SQLTransceiver.java:20)
at main.ui.toDoPane.ToDoPane.<init>(ToDoPane.java:208)
at main.ui.Window.start(Window.java:40)
at com.sun.javafx.application.LauncherImpl.lambda$launchApplication1$161(LauncherImpl.java:863)
at com.sun.javafx.application.PlatformImpl.lambda$runAndWait$174(PlatformImpl.java:326)
at com.sun.javafx.application.PlatformImpl.lambda$null$172(PlatformImpl.java:295)
at java.security.AccessController.doPrivileged(Native Method)
at com.sun.javafx.application.PlatformImpl.lambda$runLater$173(PlatformImpl.java:294)
at com.sun.glass.ui.InvokeLaterDispatcher$Future.run(InvokeLaterDispatcher.java:95)
at com.sun.glass.ui.win.WinApplication._runLoop(Native Method)
at com.sun.glass.ui.win.WinApplication.lambda$null$147(WinApplication.java:177)
at java.lang.Thread.run(Thread.java:748)
So what did I do to fix this:
It made me wonder why it doesn't state which user was denied note it statets "denied for user ''#'localhost'. So I did put in wrong password and this error came:
java.sql.SQLException: Access denied for user 'root'#'localhost' (using password: YES)
at com.mysql.cj.jdbc.exceptions.SQLError.createSQLException(SQLError.java:129)
at com.mysql.cj.jdbc.exceptions.SQLError.createSQLException(SQLError.java:97)
at com.mysql.cj.jdbc.exceptions.SQLExceptionsMapping.translateException(SQLExceptionsMapping.java:122)
at com.mysql.cj.jdbc.ConnectionImpl.createNewIO(ConnectionImpl.java:836)
at com.mysql.cj.jdbc.ConnectionImpl.<init>(ConnectionImpl.java:456)
at com.mysql.cj.jdbc.ConnectionImpl.getInstance(ConnectionImpl.java:246)
at com.mysql.cj.jdbc.NonRegisteringDriver.connect(NonRegisteringDriver.java:197)
at java.sql.DriverManager.getConnection(DriverManager.java:664)
at java.sql.DriverManager.getConnection(DriverManager.java:208)
at main.data.SQLTransceiver.reconnect(SQLTransceiver.java:31)
at main.data.SQLTransceiver.<init>(SQLTransceiver.java:26)
at main.Main.main(Main.java:29)
So it looks like it at some point does check the user and password. It just gives the first error if user and password are correct.
So I did some lookup and got the solution that is stated for this question a few times (Although often it does state the "Using password: Yes" insted of "No"):
java.sql.SQLException: Access denied for user 'root'#'localhost' (using password: YES)
It states I should run following statement:
GRANT ALL PRIVILEGES ON *.* TO 'root'#'localhost' IDENTIFIED BY '%password%' WITH GRANT OPTION;
The Problem is I can't run that. When I try to run it in MySQL Workbench I get the following error:
0 5 01:12:32 GRANT ALL PRIVILEGES ON *.* TO 'user'#'localhost' IDENTIFIED BY 'password' WITH GRANT OPTION Error Code: 1064. You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near 'IDENTIFIED BY 'password' WITH GRANT OPTION' at line 1 0.000 sec
Additionally I tried to remove MySQL completely and reinstall it. This didn't help.
Disclaimer:
Password and user was changed for privacy reasons.
In terms of errors it doesn't make a difference calling the DriverManager with connection String and Properties class I did try that to.
Sorry for more basic and maybe bad englisch.
I am using MySQL Server 8.0.20 Community with InnoDB Engine. The J/Connector and MySQL Notifier are for the same Version. I installed all (including the workbench) with the Windows Installer downloaded from: https://dev.mysql.com/downloads/mysql/
I am using Windows 10.
When I remove the "serverTimezone" parameter I get the following error:
java.sql.SQLException: The server time zone value 'Mitteleurop�ische Sommerzeit' is unrecognized or represents more than one time zone. You must configure either the server or JDBC driver (via the 'serverTimezone' configuration property) to use a more specifc time zone value if you want to utilize time zone support.
at com.mysql.cj.jdbc.exceptions.SQLError.createSQLException(SQLError.java:129)
at com.mysql.cj.jdbc.exceptions.SQLError.createSQLException(SQLError.java:97)
at com.mysql.cj.jdbc.exceptions.SQLError.createSQLException(SQLError.java:89)
at com.mysql.cj.jdbc.exceptions.SQLError.createSQLException(SQLError.java:63)
at com.mysql.cj.jdbc.exceptions.SQLError.createSQLException(SQLError.java:73)
at com.mysql.cj.jdbc.exceptions.SQLExceptionsMapping.translateException(SQLExceptionsMapping.java:76)
at com.mysql.cj.jdbc.ConnectionImpl.createNewIO(ConnectionImpl.java:836)
at com.mysql.cj.jdbc.ConnectionImpl.<init>(ConnectionImpl.java:456)
at com.mysql.cj.jdbc.ConnectionImpl.getInstance(ConnectionImpl.java:246)
at com.mysql.cj.jdbc.NonRegisteringDriver.connect(NonRegisteringDriver.java:197)
at java.sql.DriverManager.getConnection(DriverManager.java:664)
at java.sql.DriverManager.getConnection(DriverManager.java:208)
at main.data.SQLTransceiver.reconnect(SQLTransceiver.java:31)
at main.data.SQLTransceiver.<init>(SQLTransceiver.java:26)
at main.Main.main(Main.java:28)
I don't know if that helps, but it's possible.
Thanks very much in advance :)

So what at least fixed the problem was to reinstall MySQL Server again.
The difference was this time I made sure to choose the 'new' password encryption ("caching_sha2_password") for every component (Server, Connector/J, Notifier and Workbench).
Altough I don't understand how this would cause an error like this or if that even was the error it fixed it.
Thanks for everyone who did there best to help :D

Please use the following connection url:
String s = "jdbc:mysql://localhost:3306/databasename?user=user&password=password&useUnicode=true&useJDBCCompliantTimezoneShift=true&useLegacyDatetimeCode=false&serverTimezone=UTC";
I hope it's help you, thanks.

Local and Remote connection pools, Java DBCP

I have the following use-case:
I have a system that needs to use two different connection pools, One is for 'local' database (Meaning a database running on the local machine) and the other one is a 'remote' database. (Meaning a database that is running on a remote different server)
The remote database is a configuration sharing database, while the local one is has different kinds of data.
I've created two classes in order to connect to those datababase:
public class ConnectionPool {
private static BasicDataSource ds = createNewDatasource();
private static BasicDataSource createNewDatasource() {
BasicDataSource ds = new BasicDataSource();
String url = "jdbc:mysql://127.0.0.1:3306/SOME_DB"
ds.setUrl(url);
ds.setUsername(...);
ds.setPassword(...);
return ds;
}
public static Connection getConnection() throws SQLException {
return ds.getConnection();
}
}
The other class looks exactly the same, Only it's called RemoteConnection and the url is changed to:
String url = "jdbc:mysql://<REMOTE_IP>:3306/SOME_DB_2"
Running the above classes, I keep receiving the following message in my logs:
ERROR (RemoteConnection.java:40) - Failed on getConnection
java.sql.SQLException: Cannot create PoolableConnectionFactory (Access denied for user '...'#'<MACHINE_LOCAL_IP>' (using password: YES))
at org.apache.commons.dbcp2.BasicDataSource.createPoolableConnectionFactory(BasicDataSource.java:2291)
at org.apache.commons.dbcp2.BasicDataSource.createDataSource(BasicDataSource.java:2038)
at org.apache.commons.dbcp2.BasicDataSource.getConnection(BasicDataSource.java:1533)
at Censored.RemoteConnection.getConnection(RemoteConnection.java:59)
...
Caused by: java.sql.SQLException: Access denied for user '...'#'<MACHINE_LOCAL_IP>' (using password: YES)
at com.mysql.jdbc.SQLError.createSQLException(SQLError.java:965)
at com.mysql.jdbc.MysqlIO.checkErrorPacket(MysqlIO.java:3973)
at com.mysql.jdbc.MysqlIO.checkErrorPacket(MysqlIO.java:3909)
at com.mysql.jdbc.MysqlIO.checkErrorPacket(MysqlIO.java:873)
at com.mysql.jdbc.MysqlIO.proceedHandshakeWithPluggableAuthentication(MysqlIO.java:1710)
at com.mysql.jdbc.MysqlIO.doHandshake(MysqlIO.java:1226)
at com.mysql.jdbc.ConnectionImpl.coreConnect(ConnectionImpl.java:2188)
at com.mysql.jdbc.ConnectionImpl.connectOneTryOnly(ConnectionImpl.java:2219)
at com.mysql.jdbc.ConnectionImpl.createNewIO(ConnectionImpl.java:2014)
at com.mysql.jdbc.ConnectionImpl.<init>(ConnectionImpl.java:776)
at com.mysql.jdbc.JDBC4Connection.<init>(JDBC4Connection.java:47)
at sun.reflect.GeneratedConstructorAccessor31.newInstance(Unknown Source)
at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:57)
at java.lang.reflect.Constructor.newInstance(Constructor.java:437)
at com.mysql.jdbc.Util.handleNewInstance(Util.java:425)
at com.mysql.jdbc.ConnectionImpl.getInstance(ConnectionImpl.java:386)
at com.mysql.jdbc.NonRegisteringDriver.connect(NonRegisteringDriver.java:330)
at org.apache.commons.dbcp2.DriverConnectionFactory.createConnection(DriverConnectionFactory.java:39)
at org.apache.commons.dbcp2.PoolableConnectionFactory.makeObject(PoolableConnectionFactory.java:256)
at org.apache.commons.dbcp2.BasicDataSource.validateConnectionFactory(BasicDataSource.java:2301)
at org.apache.commons.dbcp2.BasicDataSource.createPoolableConnectionFactory(BasicDataSource.java:2287)
...
Firstly, The error above is weird. I've never used the machine local IP. So I don't understand where it came from. In addition, It doesn't seems like a privilege problem since I've tried logging into remote database through cli, using:
mysql -u'...' -p'...' -h <REMOTE_IP> SOME_DB_2
And it connected successfully. It smells to me like a JDBC Driver or connection definition problem but I can't seem to find the problematic spot.
Any idea what I'm doing wrong?

I've found the problem. It was an SSL issue.
The user I've used had to connect with SSL certificate.
That's also the reason why I've seen the local machine IP in the error.
A way to check is:
Select * from mysql.user where user='...';
What I've found was that:
ssl_type != ''
So I had to define:
jdbc:mysql://<REMOTE_IP>:3306/SOME_DB_2&useSSL=true
Configure the relevant certificates, and all was well.

Error when accesing MySQL database remotely using public IP

I have a MySQL database. My friend is trying to access it from a different computer using my public IP.
This is the program he used to test the connection:
public class Main {
public static void main(String args[]) {
String url = "jdbc:mysql://IPadresss:3307/javabase";
String username = "bob";
String password = "bob";
Properties properties = new Properties();
properties.setProperty("bob", "bob");
properties.setProperty("bob", "bob");
properties.setProperty("useSSL", "false");
properties.setProperty("autoReconnect", "true");
System.out.println("Connecting database...");
try (Connection connection = DriverManager.getConnection(url, properties)) {
System.out.println("Database connected!");
} catch (SQLException e) {
throw new IllegalStateException("Cannot connect the database!", e);
}
}
}
This is the error my friend, who is the client, gets:
Connecting database...
Exception in thread "main" java.lang.IllegalStateException: Cannot connect the database!
at SQLConnector.Main.main(Main.java:23)
Caused by: com.mysql.jdbc.exceptions.jdbc4.MySQLNonTransientConnectionException: Could not create connection to database server. Attempted reconnect 3 times. Giving up.
at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)
at sun.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:62)
at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:45)
at java.lang.reflect.Constructor.newInstance(Constructor.java:423)
at com.mysql.jdbc.Util.handleNewInstance(Util.java:425)
at com.mysql.jdbc.Util.getInstance(Util.java:408)
at com.mysql.jdbc.SQLError.createSQLException(SQLError.java:918)
at com.mysql.jdbc.SQLError.createSQLException(SQLError.java:897)
at com.mysql.jdbc.SQLError.createSQLException(SQLError.java:886)
at com.mysql.jdbc.SQLError.createSQLException(SQLError.java:860)
at com.mysql.jdbc.ConnectionImpl.connectWithRetries(ConnectionImpl.java:2163)
at com.mysql.jdbc.ConnectionImpl.createNewIO(ConnectionImpl.java:2088)
at com.mysql.jdbc.ConnectionImpl.<init>(ConnectionImpl.java:806)
at com.mysql.jdbc.JDBC4Connection.<init>(JDBC4Connection.java:47)
at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)
at sun.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:62)
at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:45)
at java.lang.reflect.Constructor.newInstance(Constructor.java:423)
at com.mysql.jdbc.Util.handleNewInstance(Util.java:425)
at com.mysql.jdbc.ConnectionImpl.getInstance(ConnectionImpl.java:410)
at com.mysql.jdbc.NonRegisteringDriver.connect(NonRegisteringDriver.java:328)
at java.sql.DriverManager.getConnection(DriverManager.java:664)
at java.sql.DriverManager.getConnection(DriverManager.java:208)
at SQLConnector.Main.main(Main.java:20)
Caused by: java.sql.SQLException: Access denied for user ''#'Freinds ip' (using password: NO)
at com.mysql.jdbc.SQLError.createSQLException(SQLError.java:964)
at com.mysql.jdbc.MysqlIO.checkErrorPacket(MysqlIO.java:3970)
at com.mysql.jdbc.MysqlIO.checkErrorPacket(MysqlIO.java:3906)
at com.mysql.jdbc.MysqlIO.checkErrorPacket(MysqlIO.java:873)
at com.mysql.jdbc.MysqlIO.proceedHandshakeWithPluggableAuthentication(MysqlIO.java:1710)
at com.mysql.jdbc.MysqlIO.doHandshake(MysqlIO.java:1226)
at com.mysql.jdbc.ConnectionImpl.coreConnect(ConnectionImpl.java:2253)
at com.mysql.jdbc.ConnectionImpl.connectWithRetries(ConnectionImpl.java:2104)
... 13 more
Please help me find out what is wrong with my method of connecting to the server, I have remotely given privileges to my friend (user "bob").

So, you have the following error:
com.mysql.jdbc.exceptions.jdbc4.CommunicationsException: Communications link failure java.net.ConnectException: Connection
refused
This could happen for a variety of reasons, and I'm quoting from this answer
If you get a SQLException: Connection refused or Connection timed out
or a MySQL specific CommunicationsException: Communications link
failure, then it means that the DB isn't reachable at all.
This can have one or more of the following causes:
IP address or hostname in JDBC URL is wrong.
Hostname in JDBC URL is not recognized by local DNS server.
Port number is missing or wrong in JDBC URL. [Assuming the one you mentioned is correct]
DB server is down.
DB server doesn't accept TCP/IP connections.
DB server has run out of connections.
Something in between Java and DB is blocking connections, e.g. a firewall or proxy.
To solve the one or the other, follow the following advice:
Verify and test them with ping.
Refresh DNS or use IP address in JDBC URL instead.
Verify it based on my.cnf of MySQL DB.
Start the DB.
Verify if mysqld is started without the --skip-networking option.
Restart the DB and fix your code accordingly that it closes connections in finally.
Disable firewall and/or configure
firewall/proxy to allow/forward the port.

Issue connecting to sql database from eclipse project? [duplicate]

I am trying to connect with database using jdbc in java file. It is not connecting at all and giving me the error constantly "Something went wrong"; I guess it is because of the port number because all other data such as username, password and other code seems correct.
I want to check the default port number so that I can try it properly. I did try using all three of these 8080, 80 and 3306 but it shows me error.
Here port 8080 is used for HTTP server, 3306 is supposed to be default from the research and 80 randomly.
try {
Class.forName("com.mysql.jdbc.Driver");
System.out.println("Driver found");
} catch (ClassNotFoundException e) {
System.out.println("Driver not found");
}
String url="jdbc:mysql://localhost:8080 or 80 or 3306 or without port number/test";
String user="user";
String password="";
Connection con=null;
try {
con=DriverManager.getConnection(url, user, password);
System.out.println("Success");
} catch (SQLException e){
e.printStackTrace();
}
}
The error is giving below when used String url="jdbc:mysql://localhost:3306/test";
Driver found
com.mysql.jdbc.exceptions.jdbc4.CommunicationsException: Communications link failure
The last packet sent successfully to the server was 0 milliseconds ago. The driver has not received any packets from the server.
at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)
at sun.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:39)
at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:27)
at java.lang.reflect.Constructor.newInstance(Constructor.java:513)
at com.mysql.jdbc.Util.handleNewInstance(Util.java:377)
at com.mysql.jdbc.SQLError.createCommunicationsException(SQLError.java:1036)
at com.mysql.jdbc.MysqlIO.<init>(MysqlIO.java:338)
at com.mysql.jdbc.ConnectionImpl.coreConnect(ConnectionImpl.java:2232)
at com.mysql.jdbc.ConnectionImpl.connectOneTryOnly(ConnectionImpl.java:2265)
at com.mysql.jdbc.ConnectionImpl.createNewIO(ConnectionImpl.java:2064)
at com.mysql.jdbc.ConnectionImpl.<init>(ConnectionImpl.java:790)
at com.mysql.jdbc.JDBC4Connection.<init>(JDBC4Connection.java:44)
at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)
at sun.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:39)
at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:27)
at java.lang.reflect.Constructor.newInstance(Constructor.java:513)
at com.mysql.jdbc.Util.handleNewInstance(Util.java:377)
at com.mysql.jdbc.ConnectionImpl.getInstance(ConnectionImpl.java:395)
at com.mysql.jdbc.NonRegisteringDriver.connect(NonRegisteringDriver.java:325)
at java.sql.DriverManager.getConnection(DriverManager.java:582)
at java.sql.DriverManager.getConnection(DriverManager.java:185)
at com.town.connect.Dbconnection.main(Dbconnection.java:26)
Caused by: java.net.ConnectException: Connection refused
at java.net.PlainSocketImpl.socketConnect(Native Method)
at java.net.PlainSocketImpl.doConnect(PlainSocketImpl.java:382)
at java.net.PlainSocketImpl.connectToAddress(PlainSocketImpl.java:241)
at java.net.PlainSocketImpl.connect(PlainSocketImpl.java:228)
at java.net.SocksSocketImpl.connect(SocksSocketImpl.java:431)
at java.net.Socket.connect(Socket.java:527)
at com.mysql.jdbc.StandardSocketFactory.connect(StandardSocketFactory.java:213)
at com.mysql.jdbc.MysqlIO.<init>(MysqlIO.java:297)
... 15 more

You can access those settings via
mysql> show variables;

DriverManager.getConnection("jdbc:mysql://"+dbaddress+"/"+dbname+"?user=" + username + "&password=" + password)
This statement can help you. No need to define any other port. Just define the following variables as per your mysql configuration.
dbaddress
dbname
username
password
And if this doesn't works can you post the stacktrace or a screenshot for your error ?

If you want to know the port number you can use following command
SHOW VARIABLES WHERE Variable_name = 'port';

Unable to connect to MySQL on localhost from a Java program on Ubuntu

Following is the code.
import java.sql.*;
public class ActivityReader {
public static void main(String[] args) {
System.out.println("MySQL Connect Example.");
Connection conn = null;
String url = "jdbc:mysql://localhost:3306/";
String dbName = "jdbctutorial";
String driver = "com.mysql.jdbc.Driver";
String userName = "root";
String password = "password";
try {
Class.forName("com.mysql.jdbc.Driver").newInstance();
conn = DriverManager.getConnection(url,userName,password);
System.out.println("Connected to the database");
conn.close();
System.out.println("Disconnected from database");
} catch (Exception e) {
e.printStackTrace();
}
}
}
I have already added mysql-connector-java-5.1.20-bin.jar in project from this url.
Mysql service is already running.
mysql start/running, process 25326
MySQL Connect Example.
com.mysql.jdbc.exceptions.jdbc4.CommunicationsException: Communications link failure
The last packet sent successfully to the server was 0 milliseconds ago. The driver has not received any packets from the server.
at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)
at sun.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:39)
at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:27)
at java.lang.reflect.Constructor.newInstance(Constructor.java:513)
at com.mysql.jdbc.Util.handleNewInstance(Util.java:411)
at com.mysql.jdbc.SQLError.createCommunicationsException(SQLError.java:1116)
at com.mysql.jdbc.MysqlIO.<init>(MysqlIO.java:348)
at c
om.mysql.jdbc.ConnectionImpl.coreConnect(ConnectionImpl.java:2391)
at com.mysql.jdbc.ConnectionImpl.connectOneTryOnly(ConnectionImpl.java:2428)
at com.mysql.jdbc.ConnectionImpl.createNewIO(ConnectionImpl.java:2213)
at com.mysql.jdbc.ConnectionImpl.<init>(ConnectionImpl.java:797)
at com.mysql.jdbc.JDBC4Connection.<init>(JDBC4Connection.java:47)
at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)
at sun.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:39)
at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:27)
at java.lang.reflect.Constructor.newInstance(Constructor.java:513)
at com.mysql.jdbc.Util.handleNewInstance(Util.java:411)
at com.mysql.jdbc.ConnectionImpl.getInstance(ConnectionImpl.java:389)
at com.mysql.jdbc.NonRegisteringDriver.connect(NonRegisteringDriver.java:305)
at java.sql.DriverManager.getConnection(DriverManager.java:582)
at java.sql.DriverManager.getConnection(DriverManager.java:185)
at ActivityReader.main(ActivityReader.java:45)
Caused by: java.net.ConnectException: Connection refused
at java.net.PlainSocketImpl.socketConnect(Native Method)
at java.net.PlainSocketImpl.doConnect(PlainSocketImpl.java:351)
at java.net.PlainSocketImpl.connectToAddress(PlainSocketImpl.java:213)
at java.net.PlainSocketImpl.connect(PlainSocketImpl.java:200)
at java.net.SocksSocketImpl.connect(SocksSocketImpl.java:366)
at java.net.Socket.connect(Socket.java:529)
at java.net.Socket.connect(Socket.java:478)
at java.net.Socket.<init>(Socket.java:375)
at java.net.Socket.<init>(Socket.java:218)
at com.mysql.jdbc.StandardSocketFactory.connect(StandardSocketFactory.java:257)
at com.mysql.jdbc.MysqlIO.<init>(MysqlIO.java:298)
... 15 more
Any idea.... ??????

Connect using 127.0.0.1 instead localhost, maybe a clue of what is happening on your system:
MySQL will try to connect to the unix socket if you tell it to connect
to "localhost". If you tell it to connect to 127.0.0.1 you are forcing
it to connect to the network socket. So probably you have MySQL
configured to only listen to the network socket and not to the file
system socket.
https://serverfault.com/questions/295285/mysql-cannot-connect-via-localhost-only-127-0-0-1

try
>telnet localhost 3306
You are supposed to see some server response similar to
"5.5.19☺(:*b2p`p!☻ǧ4Oph7xxsV5C5mysql_native_password"
Most probably problem will be fixed by replacing hostname with ip, check https://serverfault.com/a/90055

I think you are not specified your db name in your connection URL try this conn = DriverManager.getConnection(url +"/"+ dbName ,userName,password); And be sure that you have created the database with same name.

I face the same issue on a VPS linux server. I solve it by replacing localhost or 127.0.0.1 by the real IP address.

If you are trying to run your code on a Linux Machine or Windows Server.
You can change the server from 'localhost' to specific IP 'xx.xx.xx.xx'
and it should work fine.