我如何计算用户从5个组合框中选择的项目的总成本

Question

我已经完成了600行代码，并制作了五个组合框，我能够显示每个项目的价格，但是无法显示所选项目的总数，这里是我完成的其中一个组合框的代码。

    lights.setConverter(new StringConverter<Light>() {
        @Override
        public String toString(Light object) {
            return object.getName();
        }

        @Override
        public Light fromString(String string) {
            return null;
        }
    });



    lights.setItems(FXCollections.observableArrayList
           (new Light ("Incandescent", 5.23),
            new Light ("Halogen", 5.75),
            new Light ("fluorescent",7.29),
            new Light ("Compact fluorescent bulbs",4.83),
            new Light ("LED",4.83)));


    lights.setPromptText("Please select a light");
    lights.setPrefWidth(100);


         lights.valueProperty().addListener((obs, oldVal, newVal) -> {
         String selectionText = "The price for the " + newVal.getName() + " light is : $" + newVal.getPrice();
       lightNamePrice.setText(selectionText);
    });

 private class Light {
    private String name;
    private Double price;

    private Double getPrice() {
        return price;
    }

    private String getName() {
        return name;
    }

    private Light(String name, Double price) {
        this.name = name;
        this.price = price;

    }

}

我说的对吗？ 我该怎么做才能找到用户与其他4个此类组合框一起选择的商品的总成本？

Answer 1

使用绑定：

DoubleBinding total = Bindings.createDoubleBinding(() -> {
    double total = 0 ;
    if (lights.getValue() != null) total += lights.getValue().getPrice();
    // similarly for other combo boxes...
    return total ;
}, lights.valueProperty(), otherComboBox.valueProperty() /* etc for other combos*/);

然后你可以做类似的事情

totalPriceLabel.textProperty().bind(total.asString());