带有GUI的Java ResultSet SQL

Question

I'm having a strange problem with the below code, it works fine when its run without the if else statements, but displays no results in the jtable when if else is used. Is there something stupid I'm missing here?

        try {
        Class.forName(dbClass);
        Connection con = DriverManager.getConnection (dbUrl,dbUsername, dbPassword);
        Statement stmt = con.createStatement();

        String userQuery = "SELECT p_id AS 'Patient ID', forename AS 'Forename', surname AS 'Surname', address AS 'Address' FROM Patient WHERE surname LIKE '%"+s+"%'";
        ResultSet userResult = stmt.executeQuery(userQuery);

        if(!userResult.next())
        {
            JOptionPane.showMessageDialog(null, "No Results.");
        {
        else{
        ResultSetMetaData rsMetaData =userResult.getMetaData();
        DefaultTableModel dtm = new DefaultTableModel();
        int cols = rsMetaData.getColumnCount();
        Vector colName = new Vector();
        Vector dataRows = new Vector();

        for (int i=1; i<cols; i++){
        colName.addElement(rsMetaData.getColumnName(i));
        }
        dtm.setColumnIdentifiers(colName);

        while(userResult.next()){
            dataRows = new Vector();
            for(int j = 1; j<cols; j++){
                dataRows.addElement(userResult.getString(j));
            }
            dtm.addRow(dataRows);
        }
        searchTable.setModel(dtm);
        con.close();
        }
    } //end try

    catch(ClassNotFoundException e) {
        JOptionPane.showMessageDialog(null, "Database Error.");
        e.printStackTrace();
    }

    catch(SQLException e) {
        JOptionPane.showMessageDialog(null, "Database Error.");
        e.printStackTrace();
    }

I'm using netbeans for the GUI.

Thanks

Answer 1

The connection object (con) should be closed outside if/else block.

Beside, the userResult.next() was called twice in the else statement block..

You may fix it by replacing while() by do while loop:

do {
        dataRows = new Vector();
        for (int j = 1; j < cols; j++) {
            dataRows.addElement(userResult.getString(j));
        }
            dtm.addRow(dataRows);
    }
while (userResult.next());

Answer 2

请最后包括处理关闭连接并删除其他资源的步骤。