(report from github https://github.com/MariaDB/mariadb-connector-j/issues/35 from ocafebabe)

Some database connection pool like the one I use (Oracle UCP) will set default values for the serverName and port properties (in this case: null and 0) in org.mariadb.jdbc.MySQLDataSource.

So even though the URL I set is valid, the connection will fail because the two properties were overridden and the generated URL by the datasource implementation is then invalid: jdbc:mysql://address=(host=null)(port=0)(type=master)

PoolDataSource pds = oracle.ucp.jdbc.PoolDataSourceFactory.getPoolDataSource();

pds.setConnectionFactoryClassName("org.mariadb.jdbc.MySQLDataSource");

pds.setURL("jdbc:mysql://localhost:3306/testdb");

pds.setUser("test");

pds.setPassword("test");

Connection c = pds.getConnection();

java.sql.SQLException: Exception occurred while getting connection: oracle.ucp.UniversalConnectionPoolException: Cannot get Connection from Datasource: java.lang.IllegalArgumentException: hostname can't be null
Would it be possible to add two validation checks in org.mariadb.jdbc.MySQLDataSource as follow:

public void setServerName(String serverName) {

    if (serverName != null && !serverName.isEmpty()) {

        jdbcUrl.getHostAddresses().get(0).host = serverName;

    }

}

public void setPort(int p) {

    if (p > 0) {

        jdbcUrl.getHostAddresses().get(0).port = p;

    }

}

These validation checks are pretty generic and I don't think it would be harmful under other circumstances!