Why am I getting a NullPointerException when connecting to a MySQL database from Java?-Mysql Tutorial-php.cn

Why am I getting a NullPointerException when connecting to a MySQL database from Java?

Susan Sarandon

Release： 2024-11-16 09:00:04

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Why am I getting a NullPointerException when connecting to a MySQL database from Java?

Troubleshooting MySQL Connection Failure in Java

Problem: Connecting to a MySQL database from a Java program results in a NullPointerException error when invoking DriverManager.getConnection().

Code Example:

import java.sql.*;

public class Squirrel {
    public static void main(String[] args) {
        String user;
        String password;
        Connection connection;
        Statement statement;
        try {
            Class.forName("com.mysql.jdbc.Driver");

            connection = DriverManager.getConnection(
                "jdbc:mysql://localhost:3306", user, password);

            statement = connection.createStatement();

            // Other code
        } catch (ClassNotFoundException | SQLException e) {
            e.printStackTrace();
        } finally {
            try {
                if (statement != null) {
                    statement.close();
                }
                if (connection != null) {
                    connection.close();
                }
            } catch (SQLException e) {
                e.printStackTrace();
            }
        }
    }
}

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Error Message:

com.mysql.jdbc.exceptions.jdbc4.MySQLNonTransientConnectionException: Could not create connection to database server.
...
Caused by: java.lang.NullPointerException
    at com.mysql.jdbc.ConnectionImpl.getServerCharset(ConnectionImpl.java:2997)

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Solution:

The NullPointerException error indicates an issue with the MySQL driver initialization. The most common cause is using an outdated version of the MySQL JDBC driver.

Update the MySQL JDBC Driver:

Navigate to https://mvnrepository.com/artifact/mysql/mysql-connector-java
Download the latest version (currently 8.0.12)
Add the corresponding dependency to your Java project's pom.xml file:

<dependency>
    <groupId>mysql</groupId>
    <artifactId>mysql-connector-java</artifactId>
    <version>8.0.12</version>
</dependency>

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Additional Fix (for MySQL 8.0.1 ):

If the issue persists, it may be related to changes introduced in MySQL 8.0.1. To resolve this:

Update to MySQL JDBC Driver 5.1.41 or later
Alternatively, you can use the following optimization for MySQL 8.0.0 in your connection URL:

jdbc:mysql://localhost:3306/?useUnicode=true&characterEncoding=UTF-8&useJDBCCompliantTimezoneShift=true&useLegacyDatetimeCode=false&serverTimezone=UTC

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