java - 运行 JavaFX 容器类后如何立即隐藏 GUI 中的元素？

Question

对于我的一个 Java 项目，我使用 JavaFX 来制作收银机。 要查看 GUI 的图片，请 click here.

如 GUI 中所示，程序将要求用户输入以查找用户购买的商品数量、用户支付的金额，并在标签中显示必要的更改。但是，我想在某些点隐藏此用户界面的某些元素。目前，我知道如何使用这些命令隐藏标签和按钮:

label.setVisible(false);
button.setVisible(false);

但是，我在这里需要的是，当我运行 GUIController 类时，让标签下方的所有元素显示 + 7.00% Sales Tax 开始不可见，这样我就不必单击任何其他按钮以进行这些更改。那么，大家有什么建议吗？如有任何帮助，我们将不胜感激!

CashRegister(包含主类)

package cashregister;

import javafx.application.Application;
import javafx.fxml.FXMLLoader;
import javafx.scene.Parent;
import javafx.scene.Scene;
import javafx.stage.Stage;

/**
 *
 * @author Sammy
 */
public class CashRegister extends Application {

    @Override
    public void start(Stage stage) throws Exception {
        Parent root = FXMLLoader.load(getClass().getResource("RegisterGUI.fxml"));

        Scene scene = new Scene(root);

        stage.setScene(scene);
        stage.show();
    }

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

}

注册GUIController

(我已经省略了所有“实际”代码，这样我就不会看起来像是在对我的项目作弊)

package cashregister;

import java.net.URL;
import java.util.ResourceBundle;
import javafx.event.ActionEvent;
import javafx.fxml.FXML;
import javafx.fxml.Initializable;
import javafx.scene.control.Button;
import javafx.scene.control.Label;
import javafx.scene.control.TextField;

/**
 *
 * @author Sammy
 */
public class RegisterGUIController implements Initializable {

    @FXML
    private Label title, lblSubtotal, lblTax, lblLine, lblTotalText, lblTotal,lblChangeText, lblChange;

    @FXML
    private Button handleNoodle, handlePizza, handleWing, handlePie, handleIce;

    @FXML
    private TextField inputNoodle, inputPizza, inputWings, inputPies, inputIce, inputPayment;

    @FXML
    private void handleNoodle(ActionEvent event) {   
    }

    @FXML
    private void handlePizza(ActionEvent event) {    
    }

    @FXML
    private void handleWing(ActionEvent event) {       
    }

    @FXML
    private void handlePie(ActionEvent event) {   
    }

    @FXML
    private void handleIce(ActionEvent event) {


    }

    @Override
    public void initialize(URL url, ResourceBundle rb) {
    }    

}

注册GUI

<?xml version="1.0" encoding="UTF-8"?>

<?import javafx.scene.effect.*?>
<?import javafx.scene.text.*?>
<?import java.lang.*?>
<?import java.util.*?>
<?import javafx.scene.*?>
<?import javafx.scene.control.*?>
<?import javafx.scene.layout.*?>

<AnchorPane id="AnchorPane" maxHeight="-Infinity" maxWidth="-Infinity" prefHeight="415.0" prefWidth="320" xmlns:fx="http://javafx.com/fxml/1" xmlns="http://javafx.com/javafx/8" fx:controller="cashregister.RegisterGUIController">
    <children>
        <Button fx:id="handlePizza" layoutX="27.0" layoutY="107.0" onAction="#handlePizza" text="Pizza" AnchorPane.topAnchor="110.0" />
        <Label fx:id="title" layoutX="118.0" layoutY="14.0" minHeight="16" minWidth="69" text="Cash Register" textAlignment="CENTER" AnchorPane.rightAnchor="118.0">
         <font>
            <Font name="System Bold" size="14.0" />
         </font></Label>
      <Label layoutX="39.0" layoutY="40.0" text="Please select the items you would like to buy" />
      <Button fx:id="handlePie" layoutX="27.0" layoutY="169.0" mnemonicParsing="false" onAction="#handlePie" text="Blueberry Pie" AnchorPane.topAnchor="180.0" />
      <Button fx:id="handleWing" layoutX="27.0" layoutY="138.0" mnemonicParsing="false" onAction="#handleWings" text="Chicken Wings" AnchorPane.topAnchor="145.0" />
      <Button fx:id="handleNoodle" layoutX="27.0" layoutY="75.0" mnemonicParsing="false" onAction="#handleNoodles" text="Noodles" AnchorPane.topAnchor="75.0" />
      <Button fx:id="handleIce" layoutX="28.0" layoutY="199.0" mnemonicParsing="false" onAction="#handleIce" text="Ice Cream" AnchorPane.topAnchor="215.0" />
      <Label fx:id="lblLine" layoutX="21.0" layoutY="308.0" text="_______________________________________________________" AnchorPane.bottomAnchor="95.0" />
      <Label layoutX="57.0" layoutY="210.0" text="Subtotal:" underline="true" AnchorPane.bottomAnchor="121.0" AnchorPane.leftAnchor="57.0">
         <font>
            <Font size="12.5" />
         </font>
      </Label>
      <TextField fx:id="inputPayment" layoutX="143.0" layoutY="282.0" promptText="Enter Your Payment Here" AnchorPane.bottomAnchor="43.0" />
      <Label fx:id="lblubtotal" layoutX="113.0" layoutY="210.0" text="\$0.00" AnchorPane.bottomAnchor="121.0" AnchorPane.leftAnchor="113.0">
         <font>
            <Font size="12.5" />
         </font>
      </Label>
      <Label fx:id="lblTax" layoutX="48.0" layoutY="303.0" text="+ 7.00% Sales Tax" AnchorPane.bottomAnchor="98.0">
         <font>
            <Font size="12.5" />
         </font>
      </Label>
      <Label fx:id="lblTotalText" layoutX="14.0" layoutY="272.0" text="Total:" underline="true" AnchorPane.bottomAnchor="60.0">
         <font>
            <Font size="14.0" />
         </font>
      </Label>
      <Label fx:id="lblTotal" layoutX="57.0" layoutY="272.0" text="\$0.00" AnchorPane.bottomAnchor="60.0">
         <font>
            <Font size="14.0" />
         </font>
      </Label>
      <Button fx:id="handleDone" layoutX="177.0" layoutY="272.0" mnemonicParsing="false" onAction="#handleButton" text="Done Shopping" AnchorPane.bottomAnchor="118.0">
         <effect>
            <DropShadow blurType="GAUSSIAN" spread="0.1" />
         </effect>
      </Button>
      <Label fx:id="lblChangeText" layoutX="38.0" layoutY="295.0" text="Your Change:" AnchorPane.bottomAnchor="36.0">
         <font>
            <Font size="13.0" />
         </font>
      </Label>
      <Label fx:id="lblChange" layoutX="127.0" layoutY="296.0" text="\$0.00" AnchorPane.bottomAnchor="36.0" />
      <TextField fx:id="inputNoodles" layoutX="143.0" layoutY="75.0" onAction="#inputNoodles" promptText="# of Bowls" />
      <TextField fx:id="inputPizza" layoutX="143.0" layoutY="110.0" onAction="#inputPizza" promptText="# of Boxes" />
      <TextField fx:id="inputWings" layoutX="143.0" layoutY="145.0" onAction="#inputWings" promptText="# of Plates" />
      <TextField fx:id="inputPies" layoutX="143.0" layoutY="180.0" onAction="#inputPies" promptText="# of Pies" />
      <TextField fx:id="inputIce" layoutX="143.0" layoutY="215.0" promptText="# of Containers" />
    </children>
</AnchorPane>

Answer 1

您实际上可以将所需的代码放入初始化方法中，该方法仅在 GUI 完全设置后运行。这意味着这将像构造函数一样工作，但不会抛出 nullPointerError，因为在这部分代码运行时 GUI 已经存在。

例如，您可以在 RegisterGUIController 中执行此操作:

@Override
    public void initialize(URL url, ResourceBundle rb) {
        lblTax.setVisible(false);
        lblLine.setVisible(false);
        lblTotalText.setVisible(false);
        lblTotal.setVisible(false);
        lblChangeText.setVisible(false);
        lblChange.setVisible(false);
        inputPayment.setVisible(false);
    } 

祝您的项目顺利!