This question already has answers here:
Connect Java to a MySQL database
(14 answers)
What is a classpath and how do I set it?
(10 answers)
Closed 2 years ago.
I'm trying to connect to a database on localhost. Mysql is running and the database name is employees. I confirmed that the port, username, and password are correct.
The java, class, and jar file are in the same folder. I tried adding the jar file to my CLASSPATH in the system environment variables and I tried adding it using -cp like below.
javac -cp . relearnjdbc.java
javac -cp ./mysql-connector-java-8.0.20.jar relearnjdbc.java
javac -cp *.jar relearnjdbc.java
I also tried separating the files into their own folders src, class, and bin.
javac -cp ../bin -d ../class relearnjdbc.java
This is my code
public class relearnjdbc {
public static String url = "jdbc:mysql://localhost:3306/employees";
public static String username = "root";
public static String password = "root";
public static void main(String[] args){
System.out.println("Connecting to DB...");
try{
//Class.forName("com.mysql.jdbc.Driver");
Class.forName("com.mysql.jdbc.Driver").newInstance();
//Connection connection = DriverManager.getConnection(url, username, password);
DriverManager.getConnection(url, username, password);
System.out.println("Connected!");
}catch (Exception e){
throw new IllegalStateException("cannot connect to DB ", e);
}
}
}
These give java.lang.ClassNotFoundException. I know its deprecated, but it was in a lot of answers to similar questions.
Class.forName("com.mysql.jdbc.Driver").newInstance();
Class.forName("com.mysql.jdbc.Driver");
I'm not using an IDE, tomcat, netbeans, apache, phpadmin, or anything else. As far as I can tell a lot of other people that have asked this question were using one of these or they didn't have the jar file in their classpath.
The name of the class that implements java.sql.Driver in MySQL Connector/J has changed from com.mysql.jdbc.Driver to com.mysql.cj.jdbc.Driver. The old class name has been deprecated docs
try Class.forName("com.mysql.cj.jdbc.Driver").newInstance();
Related
I can't start "Hellow World, JDBC" app.
public static void main(String[] args) {
String username = "user";
String password = "pass";
String databaseUrl = "jdbc:mariadb://localhost:3306/example";
try{
Class.forName("org.mariadb.jdbc.Driver");
ClassLoader.getSystemClassLoader();
Connection connection = DriverManager.getConnection(databaseUrl, username, password);
} catch (ClassNotFoundException | SQLException throwables) {
throwables.printStackTrace();
}
}
I know then the error in this string. JVM can't find and load class by name, but idea seen this class.
I add mariadb connector as a jar lib. It means then idea will feed classpass to jvm when it compiling.
I also add requires org.mariadb.jdbc; in module-info.java , but I have the same error.
I've already tried creating new project. It's don't help me too. I really don't know why the JVM can't reached Driver class
The issue was in JDBC driver for mariadb v.2.7.2, 2.7.3, 2.7.4. I solved this problem by simply downgrading to an older version 2.4.4
This question already has answers here:
Connect Java to a MySQL database
(14 answers)
Closed 1 year ago.
I am currently making a backend reporting system (for a voting system assignment) using Java on VS Code, I am connecting to a MySQL database using the JDBC library in order to do calculations and stats and so on. So what happens is that once I create a project file and include the mysql-connector-java-8.0.25.jar in the referenced libraries, I can connect to the DB and retrieve data from the tables just fine, but after a few executions I no longer get output and it shows me the error "java.lang.ClassNotFoundException: com.mysql.cj.jdbc.Driver".
Can anyone tell me why this is happening and how to fix this? There are no changes that I know of taking place in the Environment Variables (at least from what I can see in Windows path list) unless something is being overwritten somewhere or that it's a bug of some sort. Any advice would be greatly helpful, I've been unable to figure this out all day
This is what my ReportSystem.java looks like...
import java.sql.*;
public class ReportSystem
{
public static void main(String[] args)
{
//Test driver connection/registration
try
{
Class.forName("com.mysql.cj.jdbc.Driver");
Connection conn = DriverManager.getConnection("jdbc:mysql://localhost:3306/ElectionDB","<username>","<password>");
Statement stmt = conn.createStatement();
ResultSet result = stmt.executeQuery("SELECT * FROM ElectionDB.Votes");
int typeColumn = 1;
int districtColumn = 2;
//Output results line by line
while(result.next())
{
System.out.println(result.getString(typeColumn));
System.out.println(result.getString(districtColumn));
}
//Remember to close the connection
conn.close();
}
catch (Exception e)
{
System.out.println(e);
}
}
}
My file structure as in the directory is as follows:
ReportSystem
>src > ReportSystem.java
> ReportSystem.class
>lib
>.vscode > settings.json
The JRE system library used is: [jdk-16.0.1]
The Referenced Libraries contains: [mysql-connector-java-8.0.25.jar]
Screenshot for context Project Setup in VS Code
I'm able to get result after running code 20 times continuously by clicking the run button. The only difference is the JDBC connection string, which is copied directly by right clicking the MYSQL connection:
So in my project, the connection string is like:
Connection conn = DriverManager.getConnection("jdbc:mysql://localhost:3306/?user=username","<username>","<password>");
OR
You could try
String url="jdbc:mysql://localhost:3306/ElectionDB?useSSL=false&allowPublicKeyRetrieval=true&serverTimezone=UTC"
For your reference, OS Infomation:
MySQL: 8.0 // mysql-connector-java-8.0.25.jar
VSCode: 1.56.2 //
java.home: JDK16 // Debugger for Java: 0.33.1
This question already has answers here:
Getting the following error - No suitable driver found for jdbc:postgresql://localhost: 5432/testDBMS
(4 answers)
Closed 3 years ago.
I'm getting an error java.sql.SQLException No suitable driver for jdbc:derby:books when I try to run a file from command line. In Eclipse, everything works fine. I read a book "Java, How To Program" Deitel&Deitel and the file is an example from it. When I try to compile program from command line it shows no error, but the problem is with running. Please help
public class DisplayAuthors {
public static void main(String args[]) {
final String DATABASE_URL = "jdbc:derby:books";
final String SELECT_QUERY =
"SELECT authorID, firstName, lastName FROM authors";
String user="deitel";
String password="deitel";
try (
Connection connection = DriverManager.getConnection(
DATABASE_URL, user,password);
Statement statement = connection.createStatement();
ResultSet resultSet = statement.executeQuery(SELECT_QUERY)) {
ResultSetMetaData metaData = resultSet.getMetaData();
int numberOfColumns = metaData.getColumnCount();
System.out.printf("Table Authors database books:%n%n");
for (int i = 1; i <= numberOfColumns; i++) {
System.out.printf("%-8s\t", metaData.getColumnName(i));
}
System.out.println();
while (resultSet.next()) {
for (int i = 1; i <= numberOfColumns; i++) {
System.out.printf("%-8s\t", resultSet.getObject(i));
}
System.out.println();
}
}
catch (SQLException sqlException) {
sqlException.printStackTrace();
}
}
}
Command line execution:
javac DisplayAuthors.java
java DisplayAuthors
You are running in the command line your class file without the dependencies.
In your eclipse IDE you maybe have a derby.jar or similar dependencies and eclipse adds all automatically to the execution. Is required to add all the dependencies when you are executing directly from the command line.
If you are note creating a runnable jar with dependencies in MANIFEST.MF and you are trying to execute the class directly is required to add the -cp parameter with the path to all the dependencies:
Example:
java -cp Derby.jar;. DisplayAuthors
Summing that the Derby.jar and your class are in the same place and there is no more dependencies to add.
More information about:
Java Command line (Oracle Java9 SE)
Differences between "java -cp" and "java -jar"?
java.sql.SQLException. No suitable driver for jdbc
The above error jumps when JDBC DriverManager can't find any suitable driver for the given connection URL. Either the JDBC driver isn't loaded at all before connecting the DB, or the connection URL is wrong.
The URL should be like this,
jdbc:derby://localhost:1527/dbname;create=true;
or
jdbc:derby:books;create=true;
Use create=true if you want the database to be created if it doesn't exist.
And finally, check that Derby JAR file is on the classpath. If you can't find it, then you can download the JAR from here and add to the project Library folder.
For Apache Derby, the driver class name is org.apache.derby.jdbc.ClientDriver. So put that as follows,
Class.forName("org.apache.derby.jdbc.ClientDriver");
Connection connection = DriverManager.getConnection(DATABASE_URL, user, password);
Make sure your URL, username and the password is correct, and try to run your code.
I have downloaded the following:
mysql-essential-5.1.65-win32 from this MySQL Dev link
MySQL Connector mysql-connector-java-5.1.21.zip from this link
Now I have started programming with Eclipse. I have made simple java class like below,
public class MySQLAccess {
private static Connection connect = null;
private Statement statement = null;
private PreparedStatement preparedStatement = null;
private ResultSet resultSet = null;
public static void main(String[] args){
try{
Class.forName ("com.mysql.jdbc.Driver").newInstance ();
}catch (Exception e) {
// TODO: handle exception
System.out.println("Error : "+e);
}
}
}
I have also made a folder "lib" in my Java project and I have put that mysql-connector jar over there. But when I run this program it can't find mysql I get the following error in the console :
Erro : java.lang.ClassNotFoundException: com.mysql.jdbc.Driver
Can someone please tell me where I have made the mistake? Thank you
Putting the full jar-file path in your classpath and restarting cmd (if you are running from cmd) should work-
See here- java.lang.ClassNotFoundException: com.mysql.jdbc.Driver
If it your java application project then you put jar file into jdk library path ext folder.
eg:
C:\Program Files\Java\jdk1.6.0_13\jre\lib\ext
you will get path from your project class path .
I have Eclipse Indigo on Mac Os X and I have downloaded mysql connector (version 5.1).
I have added the jar to the project and I am using this code:
public class Test
{
public static void main (String[] args)
{
try {
String url = "jdbc:msql://200.210.220.1:1114/Demo";
Connection conn = DriverManager.getConnection(url,"","");
Statement stmt = conn.createStatement();
ResultSet rs;
rs = stmt.executeQuery("SELECT Lname FROM Customers WHERE Snum = 2001");
while ( rs.next() ) {
String lastName = rs.getString("Lname");
System.out.println(lastName);
}
conn.close();
} catch (Exception e) {
System.err.println("Got an exception! ");
System.err.println(e.getMessage());
}
}
}
When I try to execute the program I get this exception:
Got an exception!
No suitable driver found for jdbc:msql://200.210.220.1:1114/Demo
My question is : how to install the driver? What else should I do?
And once installed the driver, how do I get my database URL (I am using mysql 5.5)?
I haven't found a valid guide on the web, they're all too specific.
Your JDBC connection URL is not correct, refer to the official documentation to check the required format for the URL .
In your case the URL will become :
String url = "jdbc:mysql://200.210.220.1:1114/Demo";
you're missing the "y" in jdbc:mysql
You are using MySQL, the URL should look like this:
jdbc:mysql://200.210.220.1:1114/Demo
may be, review the IP and PORT.
You may have added the jar to your project but have you also added it to the project classpath? Having the jar exist as a file in your project won't solve the problem. The jar file is clearly not accessible to your program. Right click on your project -> Build Path -> add the jar there.
Database URL looks ok, assuming you have the right host address and port number.