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

Question

我有一个类，它使用 GridPane 构建带有 TextFields 数组的网格。我需要将此网格插入到仅接受 setContent() 方法中的 Node 的 ScrollPane 中。所以我从 GridPane 扩展了这个类。通过 MainViewController.java 类的 onMnuItemNewAction 方法在 ScrollPane 中实例化并设置 Grid 类，但未显示网格。感谢您的帮助。

MainView.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>

Main.java

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) {

    }

}

Grid.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);
            }
        }            
    }    
}

Answer 1

Initializable

接口及其相应的

void initialize(URL, ResourceBundle)

方法旨在供充当 FXML 文档控制器的控制器类使用。当

FXMLLoader

加载在其

fx:controller

属性中指定类的 FXML 文件时，

FXMLLoader

实例化该类，然后调用其上的

initialize(...)

方法。¹

您的

Grid

类不是任何 FXML 文档的控制器类。它不是由

FXMLLoader

实例化的（您可以通过在

var newGrid = new Grid(...)

类中调用

MainViewController

直接实例化它），因此在任何时候都不会自动为您调用

initialize(...)

方法。

因此，永远不会调用

initialize()

中的

Grid

方法，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，什么也看不见。

Grid

类不需要实现

Initializable

，因为它不与FXML文件关联。

initialize()

方法中的代码是您希望在创建

Grid

时执行的代码，因此将其移动到构造函数中：

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);
            }
        }
    }

}

这给出了所需的结果：

---

对您的代码的其他评论：

注意，无需在类中复制值

horizontalGap

和

verticalGap

，因为它们已经存储为从

hgap

继承的

vgap

和

GridPane

属性。因此，您可以通过以下方式稍微减少班级规模：

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

getVgap()

来实现。

我还建议不要在这里子类化

GridPane

。当您向现有类添加功能时，应该保留子类化现有类。这里您实际上只是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，如果您想这样做，可能会使以后更改布局（例如更改为

TilePane

或其他策略）变得更加困难。我建议在这里“支持聚合而不是继承”，并且只允许访问聚合的

GridPane

，而不暴露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轻微相应的更改：

    @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，

Initializable

接口本质上是多余的。来自文档：

注意 此接口已被自动注入

location

和

resources

属性到控制器中所取代。

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。建议尽可能使用注射方式。

这意味着即使是 FXML 文档的控制器类也不需要实现

Initializable

。如果您需要在注入

@FXML

带注释的字段后执行初始化，只需定义一个无参数

initialize()

方法即可。如果你对它进行注释，你甚至可以使这个方法

private

，更好地执行封装。如果您需要访问

@FXML

或

location

属性，可以按照与 FXML 文件元素相同的方式注入这些属性。例如：resources