No operations allowed after connection closed MYSQL

Question

Basically I have:

String query = \"SELECT * FROM table WHERE UNIQUEID=? AND DIR IS NOT NULL AND NAME IS NOT NULL AND PAGETYPE IS NOT NULL\";
DBConnect Databa         


        

Answer 1

It's because of two reasons:

• Connection is closed after the execution of first PreparedStatement
• getcon uses an instance variable instead of local variable. Due to this, same conn variable (the one that was closed earlier) gets returned when getcon is called next time.

To fix this, getcon and DBConnect need to be modified to declare a local conn variable and return it (in fact, you don't need DBConnect at all), e.g.:

public Connection getcon(){
    try{
        Class.forName("com.mysql.jdbc.Driver");
        String unicode="useSSL=false&autoReconnect=true&useUnicode=yes&characterEncoding=UTF-8";
        return DriverManager.getConnection("jdbc:mysql://localhost:15501/duckdb?"+unicode, "root", "_PWD");
    }catch(Exception ex){
        System.out.println(ex.getMessage());
        System.out.println("couldn't connect!");
        throw new RuntimeException(ex);
    }
}