This code defines a class called "conexion" that establishes a connection to a MySQL database. It imports the necessary MySQL driver, connects to the specified local database called "prueba" with username "root" and empty password, and handles any connection errors. The main method then creates an instance of the conexion class, executes a SQL query to select all data from the "usuario" table, iterates through the result set and prints out the id and user fields, then closes the connection.

5. public class conexion {
Connection con;
public conexion(){
try {
Class.forName("com.mysql.jdbc.Driver");
con=(Connection) DriverManager.getConnection("jdbc:mysql://localhost:3306/prueba","root","");
} catch (Exception e) {
System.err.println("Error:" +e);
}
}
public static void main(String[] args) {
conexion cn=new conexion();
Statement st;
ResultSet rs;
try {
st=cn.con.createStatement();
rs=st.executeQuery("select * from usuario");
while (rs.next()) {
System.out.println(rs.getInt("id")+" " +rs.getString("user"));
}
cn.con.close();
} catch (Exception e) {
}
}
}