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Accepted
Adalberto José Brasaca
Asked: 2024-10-20 22:48:47 +0800 CST

将复合对象（带有 TextFields 的 GridPane）插入到 ScrolPane 中

  • 772

我有一个使用 GridPane 构建带有 TextFields 数组的网格的类。我需要将此网格插入到只接受 setContent() 方法中的 Node 的 ScrollPane 中。因此我从 GridPane 扩展了此类。Grid 类由 MainViewController.java 类的 onMnuItemNewAction 方法在 ScrollPane 中实例化和设置，但网格未显示。感谢您的帮助。

主视图.fxml

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

<?import javafx.scene.control.Menu?>
<?import javafx.scene.control.MenuBar?>
<?import javafx.scene.control.MenuItem?>
<?import javafx.scene.control.ScrollPane?>
<?import javafx.scene.layout.BorderPane?>
<?import javafx.scene.layout.VBox?>

<BorderPane prefHeight="277.0" prefWidth="495.0" xmlns="http://javafx.com/javafx/17" xmlns:fx="http://javafx.com/fxml/1" 
fx:controller="br.com.ablogic.crossword.MainViewController">
    <top>
       <VBox prefWidth="100.0" BorderPane.alignment="CENTER">
         <children>
            <MenuBar fx:id="mnuBar" prefHeight="25.0" prefWidth="360.0">
              <menus>
                <Menu mnemonicParsing="false" text="File">
                  <items>
                    <MenuItem fx:id="mnuItemNew" mnemonicParsing="false" onAction="#onMnuItemNewAction" text="New grid" />
                  </items>
                </Menu>
              </menus>
            </MenuBar>
         </children>
      </VBox>
   </top>
   <center>
      <ScrollPane fx:id="scpGrid" fitToHeight="true" fitToWidth="true" pannable="true" style="-fx-background-color: #dbbb92; -fx-background: #dbbb92;" BorderPane.alignment="CENTER" />
   </center>
</BorderPane>

主程序

import javafx.application.Application;
import javafx.fxml.FXMLLoader;
import javafx.scene.Scene;
import javafx.stage.Stage;
import java.io.IOException;

public class Main extends Application {
    @Override
    public void start(Stage stage) throws IOException {

        FXMLLoader fxmlLoader = new FXMLLoader(Main.class.getResource("MainView.fxml"));
        Scene scene = new Scene(fxmlLoader.load(), 800, 600);
        stage.setTitle("Grid Demo");
        stage.setScene(scene);
        stage.show();
    }

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

}

MainViewController.java（调用方法）

import javafx.geometry.Pos;
import javafx.scene.control.MenuItem;
import javafx.scene.control.ScrollPane;
import javafx.fxml.FXML;
import javafx.fxml.Initializable;
import java.net.URL;
import java.util.ResourceBundle;

public class MainViewController implements Initializable {

    @FXML
    private MenuItem mnuItemNew;

    @FXML
    private ScrollPane scpGrid;

    @FXML
    public void onMnuItemNewAction() {
        int cols = 10;
        int rows = 10;
        int horizontalGap = 1;
        int verticalGap = 1;
        int fieldHorizontalSize = 40;
        int fieldVerticalSize = 40;
        var newGrid = new Grid(cols, rows, horizontalGap, verticalGap, fieldHorizontalSize, fieldVerticalSize);
        scpGrid.setContent(newGrid);
        newGrid.setAlignment(Pos.CENTER);
    }

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

    }

}

网格.java

import javafx.fxml.Initializable;
import javafx.scene.control.TextField;
import javafx.scene.layout.GridPane;
import java.net.URL;
import java.util.ResourceBundle;

public class Grid extends GridPane implements Initializable {
    private final int totalColumnFields;
    private final int totalRowFields;
    private final int horizontalGap;
    private final int verticalGap;
    private final int fieldHorizontalSize;
    private final int fieldVerticalSize;
        
    public Grid(int totalColumnFields, int totalRowFields, int horizontalGap, int verticalGap, int fieldHorizontalSize, int fieldVerticalSize) {
        this.totalColumnFields = totalColumnFields;
        this.totalRowFields = totalRowFields;
        this.horizontalGap = horizontalGap;
        this.verticalGap = verticalGap;
        this.fieldHorizontalSize = fieldHorizontalSize;
        this.fieldVerticalSize = fieldVerticalSize;
    }

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

        this.setHgap(horizontalGap);
        this.setVgap(verticalGap);
        TextField[][] arrayLetterField = new TextField[totalColumnFields][totalRowFields];

        for (int row = 0; row < totalRowFields; row++) {
            for (int col = 0; col < totalColumnFields; col++) {
                arrayLetterField[col][row] = new TextField();
                arrayLetterField[col][row].setMinSize(fieldHorizontalSize, fieldVerticalSize);
                arrayLetterField[col][row].setMaxSize(fieldHorizontalSize, fieldVerticalSize );
                this.add(arrayLetterField[col][row], col, row);
            }
        }            
    }    
}
java

1 个回答

  1. Best Answer

    该Initializable接口及其相应的void initialize(URL, ResourceBundle)方法旨在供控制器类用作 FXML 文档的控制器。当FXMLLoader加载在其属性中指定类的 FXML 文件时fx:controller，会FXMLLoader实例化该类，然后initialize(...)对其调用该方法。1

    您的Grid类不是任何 FXML 文档的控制器类。它不是由实例化（您通过调用类FXMLLoader直接实例化它），因此该方法不会在任何时候自动为您调用。var newGrid = new Grid(...)MainViewControllerinitialize(...)

    因此，永远不会调用initialize()中的方法Grid，因此永远不会创建文本字段，也永远不会将其添加到网格窗格中。因此，您添加到滚动窗格的网格是空的，并且什么都看不到。

    类无需Grid实现Initializable，因为它与 FXML 文件无关。initialize()方法中的代码是您希望在Grid创建时执行的代码，因此将其移至构造函数：

    import javafx.scene.control.TextField;
import javafx.scene.layout.GridPane;

public class Grid extends GridPane {
    private final int totalColumnFields;
    private final int totalRowFields;
    private final int horizontalGap;
    private final int verticalGap;
    private final int fieldHorizontalSize;
    private final int fieldVerticalSize;

    public Grid(int totalColumnFields, int totalRowFields, int horizontalGap, int verticalGap, int fieldHorizontalSize, int fieldVerticalSize) {
        this.totalColumnFields = totalColumnFields;
        this.totalRowFields = totalRowFields;
        this.horizontalGap = horizontalGap;
        this.verticalGap = verticalGap;
        this.fieldHorizontalSize = fieldHorizontalSize;
        this.fieldVerticalSize = fieldVerticalSize;
        this.setHgap(horizontalGap);
        this.setVgap(verticalGap);
        TextField[][] arrayLetterField = new TextField[totalColumnFields][totalRowFields];

        for (int row = 0; row < totalRowFields; row++) {
            for (int col = 0; col < totalColumnFields; col++) {
                arrayLetterField[col][row] = new TextField();
                arrayLetterField[col][row].setMinSize(fieldHorizontalSize, fieldVerticalSize);
                arrayLetterField[col][row].setMaxSize(fieldHorizontalSize, fieldVerticalSize );
                this.add(arrayLetterField[col][row], col, row);
            }
        }
    }

}

    这给出了期望的结果：

    窗口中显示的文本字段网格的屏幕截图

    关于您的代码的其他评论：

    请注意，无需在类中复制值horizontalGap和，因为这些值已存储为从继承的和属性。因此，您可以使用以下方法稍微减小类的大小：verticalGaphgapvgapGridPane

    public class Grid extends GridPane {
    private final int totalColumnFields;
    private final int totalRowFields;
    private final int fieldHorizontalSize;
    private final int fieldVerticalSize;

    public Grid(int totalColumnFields, int totalRowFields, int horizontalGap, int verticalGap, int fieldHorizontalSize, int fieldVerticalSize) {
        this.totalColumnFields = totalColumnFields;
        this.totalRowFields = totalRowFields;
        this.fieldHorizontalSize = fieldHorizontalSize;
        this.fieldVerticalSize = fieldVerticalSize;
        this.setHgap(horizontalGap);
        this.setVgap(verticalGap);
        TextField[][] arrayLetterField = new TextField[totalColumnFields][totalRowFields];

        for (int row = 0; row < totalRowFields; row++) {
            for (int col = 0; col < totalColumnFields; col++) {
                arrayLetterField[col][row] = new TextField();
                arrayLetterField[col][row].setMinSize(fieldHorizontalSize, fieldVerticalSize);
                arrayLetterField[col][row].setMaxSize(fieldHorizontalSize, fieldVerticalSize );
                this.add(arrayLetterField[col][row], col, row);
            }
        }
    }
}

    如果您需要随时引用这些值，可以使用getHgap()和 来引用getVgap()。

    我还建议不要GridPane在此处进行子类化。在向现有类添加功能时，应保留对现有类进行子类化。在这里，您实际上只是在配置现有类的一个实例。子类化GridPane还会向应用程序的其余部分公开布局策略的内部细节，这可能会使以后更改布局（例如，更改为TilePane某种其他策略）变得更加困难（如果您想要这样做的话）。我建议在此处“优先使用聚合而不是继承”，并且只允许访问聚合，GridPane而不公开您正在使用的布局的详细信息：

    import javafx.scene.Node;
import javafx.scene.control.TextField;
import javafx.scene.layout.GridPane;

public class Grid {
    private final int totalColumnFields;
    private final int totalRowFields;
    private final int fieldHorizontalSize;
    private final int fieldVerticalSize;

    private final GridPane grid;

    public Grid(int totalColumnFields, int totalRowFields, int horizontalGap, int verticalGap, int fieldHorizontalSize, int fieldVerticalSize) {
        this.totalColumnFields = totalColumnFields;
        this.totalRowFields = totalRowFields;
        this.fieldHorizontalSize = fieldHorizontalSize;
        this.fieldVerticalSize = fieldVerticalSize;

        grid = new GridPane();
        grid.setHgap(horizontalGap);
        grid.setVgap(verticalGap);
        TextField[][] arrayLetterField = new TextField[totalColumnFields][totalRowFields];

        for (int row = 0; row < totalRowFields; row++) {
            for (int col = 0; col < totalColumnFields; col++) {
                arrayLetterField[col][row] = new TextField();
                arrayLetterField[col][row].setMinSize(fieldHorizontalSize, fieldVerticalSize);
                arrayLetterField[col][row].setMaxSize(fieldHorizontalSize, fieldVerticalSize );
                grid.add(arrayLetterField[col][row], col, row);
            }
        }
    }

    public Node getView() {
        return grid;
    }

}

    然后对客户端代码进行相应的细微修改：

        @FXML
    public void onMnuItemNewAction() {
        int cols = 10;
        int rows = 10;
        int horizontalGap = 1;
        int verticalGap = 1;
        int fieldHorizontalSize = 40;
        int fieldVerticalSize = 40;
        var newGrid = new Grid(cols, rows, horizontalGap, verticalGap, fieldHorizontalSize, fieldVerticalSize);
        var gridView = newGrid.getView();
        scpGrid.setContent(gridView);
        gridView.setStyle("-fx-alignment: center;");
    }

    （1）请注意，从 JavaFX 2.1 开始，该Initializable接口本质上是多余的。摘自文档：

    注意：此接口已被自动将location和resources属性注入控制器所取代。FXMLLoader现在将自动调用控制器定义的任何适当注释的无参数initialize()方法。建议尽可能使用注入方法。

    这意味着，即使是 FXML 文档的控制器类也无需实现Initializable。如果您需要在@FXML注入 -annotated 字段后执行初始化，只需定义一个无参数initialize()方法即可。您甚至可以private在注释此方法后使它成为@FXML，从而更好地执行封装。如果您需要访问location或resources属性，则可以以与 FXML 文件的元素相同的方式注入它们。例如：

    public class MainViewController {

    @FXML
    private MenuItem mnuItemNew;

    @FXML
    private ScrollPane scpGrid;
    
    @FXML
    // Can omit this field if it is not needed
    // (It is very rare to need this.)
    private URL location;

    @FXML
    private void onMnuItemNewAction() {
        int cols = 10;
        int rows = 10;
        int horizontalGap = 1;
        int verticalGap = 1;
        int fieldHorizontalSize = 40;
        int fieldVerticalSize = 40;
        var newGrid = new Grid(cols, rows, horizontalGap, verticalGap, fieldHorizontalSize, fieldVerticalSize);
        var gridView = newGrid.getView();
        scpGrid.setContent(gridView);
        gridView.setStyle("-fx-alignment: center;");
    }

    @FXML
    private void initialize() {
        // Any required initialization code here
        // If no intialization needed, this method can be omitted
    }

}
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