我如何打印返回ArrayList？

Question

我有一个生成并返回ArrayList的方法。如何从其他类打印ArrayList？

    public ArrayList<Printer> selectAllePrinters() {
    ArrayList<Printer> printers = new ArrayList<>();
    try {
        Connection con = SimpleDataSource.getConnection();
        PreparedStatement stat = con.prepareStatement("SELECT * FROM printer;");
        ResultSet result = stat.executeQuery();
        while (result.next()) {
            Printer printer = new Printer();
            printer.setPrinterid(result.getString("printerid"));
            printer.setNaam(result.getString("printernaam"));
            printer.setAantalKl(result.getInt("aantalkleur"));
            printer.setAantalZw(result.getInt("aantalzwart"));
        }
        result.close();
        stat.close();
        return printers;
    } catch (SQLException e) {
        System.out.println(e);
        return null;
    }
}

提前致谢！

Answer 1

在您的方法中，将新打印机添加到arraylist。

while (result.next()) {
    Printer printer = new Printer();
    printer.setPrinterid(result.getString("printerid"));
    printer.setNaam(result.getString("printernaam"));
    printer.setAantalKl(result.getInt("aantalkleur"));
    printer.setAantalZw(result.getInt("aantalzwart"));
    printers.add(printer); // Adds the printer to the arraylist.
}

然后打印出来。

System.out.println(selectAllePrinters());