Type mismatch: Cannot convert from java.sql.statement to com.mysql.jdbc.Statement [duplicate]

Question

This is the code I am working with to connect to a mysql database.

I am getting this error: Type mismatch: Cannot convert from java.sql.statement to com.mysql.jdbc.Statement

The line: Statement getData=con.createStatement(); //ERROR HERE

Do I have a class loading issue?

//connect to database

import java.sql.Connection;
import java.sql.Driver;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Date;

import com.mysql.jdbc.Statement; 



public class dbconn {
    public static void main(String args[]) {

        String username = "username";
        String password = "password";
        String url = "jdbc:mysql://localhost:3306/Databasename";

        try {

        Class.forName("com.mysql.jdbc.Driver");
        Connection con=DriverManager.getConnection(url, username, password);
        Statement getData=con.createStatement(); //ERROR HERE
        ResultSet rs = getData.executeQuery("select * from MY_TABLE_NAME");
        while(rs.next())
            System.out.println(rs.getDate(1));
        con.close();

    }catch(Exception e) {System.out.println(e);}


    }


}

you should import import java.sql.Statement not com.mysql.jdbc.Statement — Madhawa Priyashantha
– Madhawa Priyashantha, Commented Oct 29, 2017 at 2:31

Stephen C · Accepted Answer · 2017-10-29 02:45:19Z

4

This statement:

 Statement getData = con.createStatement();

won't compile because the signature of createStatement() says that it returns a java.sql.Statement. But you have imported com.mysql.jdbc.Statement, and that means that Statement means com.mysql.jdbc.Statement.

Solutions:

Fix the import statement (preferred!!).
Cast the returned value to Statement. This kind of works, but you are doing an unnecessary runtime type-check (that could fail!) AND the code will break if you change your JDBC driver to some other vendor's.

Lessons:

Don't blindly accept your IDE's suggestions / completions for imports. They may be incorrect.
If you are designing an API yourself, avoid the temptation of picking a class or interface name that is the same one used in the Java SE class libraries.

answered Oct 29, 2017 at 2:45

Stephen C

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