Java 我无法在文本区域中显示多个输入

我已经写了一个308行的比萨饼图形用户界面，用于几天后到期的家庭作业。我已经测试了所有的东西，代码也能正常工作

我的问题是，我要求用户在每个比萨饼上选择他们想要的配料、大小和比萨饼类型，然后用户将他们的选择添加到购物车中，并提示他们添加另一个比萨饼或结帐

如果用户签出数据，则显示为：

Your Order Number: 1
Pizza Type: Thin Crust
Pizza Size: Medium
Toppings: Cheese, Green Peppers
Total $11.50

Your Receipt:
Subtotal: $11.50
Tax: $1.06
Amount Due: $12.56

这是正确的输出。当用户选择多个比萨饼时，就会出现问题。如果用户选择两个比萨饼，则只记录最近的比萨饼。因此，打印信息会显示您的订单号2，但不包括订单1。我希望显示屏显示所有订单。我尝试了一些不同的方法，我认为我的问题必须处理ordertext，但我不是100%确定

我在下面加了一小部分，我希望有人能发现我遗漏了什么

    // Creating the "Pizza Type" radiobutton grid
    VBox gridForRadioButtons2 = new VBox(20);
    gridForRadioButtons2.setPadding(new Insets(5, 5, 5, 5)); 
    gridForRadioButtons2.setStyle
      ("2px; -fx-border-color: red");
    Text PTtext = new Text("Pizza Type");
    PTtext.setFill (Color.RED);
    RadioButton rbTC = new RadioButton("Thin Crust");
    RadioButton rbMC = new RadioButton("Medium Crust");
    RadioButton rbP = new RadioButton("Pan");
    gridForRadioButtons2.getChildren().addAll(PTtext, rbTC, rbMC, rbP);
    grid.add(gridForRadioButtons2, 2, 1);

        ToggleGroup group2 = new ToggleGroup();
        rbTC.setToggleGroup(group2);
        rbMC.setToggleGroup(group2);
        rbP.setToggleGroup(group2);

    // Create a new text area
    TextArea orderscreen = new TextArea();
    orderscreen.setPrefColumnCount(25);
    orderscreen.setPrefRowCount(7);    
    grid.add(orderscreen, 0, 4);


        btnAC.setOnAction((ActionEvent event) -> {
        String mytoppings = "";
        double mytopcost = 0.0;

            // Processing button logic & checkboxes logic
            if (chkTom.isSelected()) {
                mytoppings = mytoppings + "Tomato "; // Topping
                mytopcost += 1.50; // price
            }

            if (chkGP.isSelected()) {
                mytoppings = mytoppings + "Green Peppers "; // Topping
                mytopcost += 1.50; // pice
            }

            if (chkBO.isSelected()) {
                mytoppings = mytoppings + "Black Olives "; // Topping
                mytopcost += 1.50; // pice
            }

            if (chkMR.isSelected()) {
                mytoppings = mytoppings + "MushRooms "; // Topping
                mytopcost += 1.50; // pice
            }

            if (chkEC.isSelected()) {
                mytoppings = mytoppings + "Extra Cheese "; // Topping
                mytopcost += 1.50; // pice
            }

            if (chkPep.isSelected()) {
                mytoppings = mytoppings + "Peppeoni "; // Topping
                mytopcost += 1.50; // pice
            }

            if (chkSS.isSelected()) {
                mytoppings = mytoppings + "Sausage "; // Topping
                mytopcost += 1.50; // pice

            }
            if (mytoppings.length() < 2)
            {mytoppings = mytoppings + "no toppings selected";}


        // Pizza Types logic
        String mypizzatype = "";

            if (rbTC.isSelected()) {
                mypizzatype = mypizzatype + "Thin Crust "; // Type
            }

            if (rbMC.isSelected()) {
                mypizzatype = mypizzatype + "Medium Crust "; // Type
            }

            if (rbP.isSelected()) {
                mypizzatype = mypizzatype + "Pan "; // Type
            }

        // Pizza Sizes logic
        String mypizzasize = "";
        Double smpzcost = 6.50;
        Double mdpzcost = 8.50;
        Double lgpzcost = 10.00;

            if (rbSM.isSelected()) {
                mypizzasize = mypizzasize + "Small "; // Pizza Type
                order = smpzcost;
            }

            if (rbMD.isSelected()) {
                mypizzasize = mypizzasize + "Medium "; // Pizza Type
                order = mdpzcost;
            }

            if (rbLG.isSelected()) {
                mypizzasize = mypizzasize + "Large "; // Pizza Type
                order = lgpzcost;
            }

        // Storing the order text
            DecimalFormat df = new DecimalFormat("0.00");
            ordertext = "Your Order Number: "
                    + numberPizzas
                    + "\nPizza Type: " + mypizzatype
                    + "\nPizza Size: " + mypizzasize
                    + "\nToppings: " + mytoppings
                    + "\nTotal: $" +  df.format(order + mytopcost)
                    + "\n";
            total = (order + mytopcost);
            numberPizzas++;
            pizzas = pizzas + total;

            // Display order text
            orderscreen.setText(ordertext);
    });


    btnAddPizza.setOnAction(e -> {
        chkTom.setSelected(false);
        chkGP.setSelected(false);
        chkBO.setSelected(false);
        chkMR.setSelected(false);
        chkEC.setSelected(false);
        chkPep.setSelected(false);
        chkSS.setSelected(false);
        chkMR.setSelected(false);
        rbSM.setSelected(false);
        rbMD.setSelected(false);
        rbLG.setSelected(false);
        rbTC.setSelected(false);
        rbMC.setSelected(false);
        rbP.setSelected(false);
    });

            btnChkOut.setOnAction(e -> {
        // Storing the order text
        DecimalFormat df = new DecimalFormat("0.00");
                tax = pizzas*.0925;
        tax = pizzas *.0925;
        subtotal = pizzas + tax;
              ordertext =   ("Your Receipt: "
                      + "\nSubtotal: " + df.format(pizzas)
                      + "\nSales Tax: " + df.format(tax)
                      + "\nAmount Due: " + df.format(subtotal)
                      + "\n");

              // Display order text
              orderscreen.setText(ordertext);
    });



    primaryStage.setTitle("Justin's Pizza Palace Shop");
    primaryStage.setScene(scene);
    primaryStage.show();
}

/**
 * @param args the command line arguments
 */
public static void main(String[] args) {
    launch(args);

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你如何储存你的比萨饼？我看到了一个比萨饼的逻辑，倍数从何而来？在顶部的双层比萨饼；啊!！！我刚想出来