Java fxml从表单返回值答案

【问题标题】：Java fxml return value from formJava fxml从表单返回值
【发布时间】：2018-12-06 00:28:06
【问题描述】：

我遇到了一个问题，我似乎无法使用 fxml 从 javafx 中的新表单返回值。

我正在尝试创建一个与 connect 4 游戏相关的具有 4 个功能的主窗体开始游戏、查看玩家、查看游戏、查看玩家游戏

当我启动程序时，会弹出主菜单，然后我想点击“开始游戏”按钮。之后打开它会提示输入用户 1 的信息。然后它会弹出一个关于玩家信息的新表单。

我遇到的问题是，单击接受按钮后，类中的变量变为空我尝试通过实例获取方法从主菜单类访问并返回主类。

在 ShowAndWait 行之后，变量似乎被清空了。如何在 windows 之后检索变量信息（以 c# 方式）

package Homework_5;

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

import java.util.ArrayList;

public class Connect4Window extends Application {
    ArrayList<Connect4Game> games = new ArrayList<>();

    public static void main(String[] args) {
        launch(args);
    }

    @Override
    public void start(Stage primaryStage) throws Exception{
        Parent root = FXMLLoader.load(getClass().getResource("FXML_Files/MainMenu.fxml"));
        primaryStage.setTitle("Connect 4");
        primaryStage.setScene(new Scene(root));
        primaryStage.show();
    }
}

MainMenu 类

package Homework_5.FXML_Java_Classes;

import Homework_5.DataClasses.PersonData;
import javafx.event.ActionEvent;
import javafx.fxml.FXML;
import javafx.fxml.Initializable;
import javafx.scene.control.Alert;
import javafx.scene.control.Button;

public class MainMenu {

    @FXML
    private Button btnViewGames;

    @FXML
    private Button btnViewPlayers;

    @FXML
    private Button btnStartGame;

    @FXML
    private Button btnViewPlayerGames;

    @FXML
    void startGame(ActionEvent event) {
        Alert alert = new Alert(Alert.AlertType.NONE, "Please enter player 1 info");
        alert.setHeaderText(null);
        alert.setTitle("Player 1 info");
        alert.showAndWait();

        PlayerInfo playerInfo = new PlayerInfo();
        playerInfo.Show();
        System.out.println(playerInfo.getTxtName()); //Shows null
        System.out.println(playerInfo.isInfoAccepted()); //Shows null
        System.out.println(playerInfo.getChkComputer()); //Shows null
        System.out.println(playerInfo.getColor()); //Shows null
    }

    @FXML
    void viewPlayers(ActionEvent event) {
        System.out.println("view players");
    }

    @FXML
    void viewPlayerGames(ActionEvent event) {
        System.out.println("view playergames");
    }

    @FXML
    void viewGames(ActionEvent event) {
        System.out.println("view games");
    }
}

玩家信息类

package Homework_5.FXML_Java_Classes;

import Homework_5.DataClasses.PersonData;
import javafx.event.ActionEvent;
import javafx.fxml.FXML;
import javafx.fxml.FXMLLoader;
import javafx.scene.Parent;
import javafx.scene.Scene;
import javafx.scene.control.*;
import javafx.scene.paint.Color;
import javafx.stage.Modality;
import javafx.stage.Stage;
import javafx.stage.StageStyle;

public class PlayerInfo {

    @FXML
    private Button btnAccept;

    @FXML
    private ColorPicker colorColorPicker;

    @FXML
    private CheckBox chkComputer;

    @FXML
    private TextField txtName;

    @FXML
    private Button btnClear;

    private boolean infoAccepted = false;

    public PlayerInfo(){

    }

    public PersonData Show()
    {
        try{
            FXMLLoader fxmlLoader = new FXMLLoader(getClass().getResource("../FXML_Files/PlayerInfo.fxml"));
            Parent root1 = fxmlLoader.load();
            Stage stage = new Stage();
            stage.initModality(Modality.WINDOW_MODAL);
            stage.setTitle("Enter Player Information");
            stage.setScene(new Scene(root1));
            stage.showAndWait();
            return new PersonData(txtName.getText(), colorColorPicker.getValue(), chkComputer.isSelected());
        } catch (Exception e)
        {
            e.printStackTrace();
        }
        return null;
    }

    @FXML
    void Accept(ActionEvent event) {
        if (txtName.getText().isEmpty()) {
            Alert alert = new Alert(Alert.AlertType.WARNING, "The name field is blank!\n\nPlease enter a name.");
            alert.setHeaderText(null);
            alert.setTitle("Name Blank");
            alert.showAndWait();
        } else {
            infoAccepted = true;
            Stage stage = (Stage) btnAccept.getScene().getWindow();
            stage.close();
        }
    }

    @FXML
    void Clear(ActionEvent event) {
        txtName.clear();
        colorColorPicker.setValue(Color.WHITE);
        chkComputer.setSelected(false);
    }

    public Color getColor() {
        return colorColorPicker.getValue();
    }

    public boolean getChkComputer() {
        return chkComputer.isSelected();
    }

    public String getTxtName() {
        return txtName.getText();
    }

    public boolean isInfoAccepted() {
        return infoAccepted;
    }
}

MainMenu fxml

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

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

<AnchorPane prefHeight="81.0" prefWidth="442.0" xmlns="http://javafx.com/javafx/8" xmlns:fx="http://javafx.com/fxml/1" fx:controller="Homework_5.FXML_Java_Classes.MainMenu">
   <children>
      <Button fx:id="btnStartGame" layoutX="14.0" layoutY="14.0" mnemonicParsing="false" onAction="#startGame" prefHeight="55.0" prefWidth="86.0" text="Start Game" />
      <Button fx:id="btnViewPlayers" layoutX="110.0" layoutY="14.0" mnemonicParsing="false" onAction="#viewPlayers" prefHeight="55.0" prefWidth="86.0" text="View Players" />
      <Button fx:id="btnViewPlayerGames" layoutX="302.0" layoutY="14.0" mnemonicParsing="false" onAction="#viewPlayerGames" prefHeight="55.0" prefWidth="127.0" text="View Player Games" />
      <Button fx:id="btnViewGames" layoutX="206.0" layoutY="14.0" mnemonicParsing="false" onAction="#viewGames" prefHeight="55.0" prefWidth="86.0" text="View Games" />
   </children>
</AnchorPane>

玩家信息 fxml

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

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

<AnchorPane prefHeight="201.0" prefWidth="213.0" rotate="-0.0" xmlns="http://javafx.com/javafx/8" xmlns:fx="http://javafx.com/fxml/1" fx:controller="Homework_5.FXML_Java_Classes.PlayerInfo">
   <children>
      <Button fx:id="btnAccept" cancelButton="true" layoutX="14.0" layoutY="165.0" mnemonicParsing="false" onAction="#Accept" text="Accept" />
      <Button fx:id="btnClear" layoutX="156.0" layoutY="165.0" mnemonicParsing="false" onAction="#Clear" text="Clear" />
      <CheckBox fx:id="chkComputer" layoutX="57.0" layoutY="126.0" mnemonicParsing="false" text="Computer" />
      <ColorPicker fx:id="colorColorPicker" layoutX="57.0" layoutY="81.0" />
      <TextField fx:id="txtName" layoutX="57.0" layoutY="41.0" />
      <Label contentDisplay="CENTER" layoutX="14.0" layoutY="14.0" text="Please Enter User Information below" />
      <Label layoutX="14.0" layoutY="45.0" text="Name:" />
      <Label layoutX="14.0" layoutY="85.0" text="Color:" />
   </children>
</AnchorPane>

【问题讨论】：

标签： java javafx netbeans fxml

【解决方案1】：

您调用Show() 的PersonInfo 实例不是与PlayerInfo.fxml 一起使用的实例。如果提供了fx:controller 属性，FXMLLoader 创建控制器类的新实例。要访问此实例，请在调用load() 后使用FXMLLoader 的getController 方法。

你可以例如创建一个static 方法加载并使用它来创建控制器：

public class PlayerInfo {

    @FXML
    private Parent root1;

    public static PlayerInfo create() throws Exception {
        FXMLLoader fxmlLoader = new FXMLLoader(getClass().getResource("../FXML_Files/PlayerInfo.fxml"));
        fxmlLoader.load();
        return fxmlLoader.getController();
    }

    public PersonData Show() {
        Stage stage = new Stage();
        stage.initModality(Modality.WINDOW_MODAL);
        stage.setTitle("Enter Player Information");
        stage.setScene(new Scene(root1));
        stage.showAndWait();
        return new PersonData(txtName.getText(), colorColorPicker.getValue(), chkComputer.isSelected());
    }
    ...
}

<AnchorPane fx:id="root1" prefHeight="201.0" prefWidth="213.0" rotate="-0.0" xmlns="http://javafx.com/javafx/8" xmlns:fx="http://javafx.com/fxml/1" fx:controller="Homework_5.FXML_Java_Classes.PlayerInfo">
    ...

PlayerInfo playerInfo = PlayerInfo.create();
playerInfo.Show();

或者，您可以使用<fx:root> 并从“控制器”的构造函数中加载 fxml，请参阅custom component approach in Introduction to FXML

【讨论】：