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JavaFX - FXML 文件中的自定義 object

[英]JavaFX - custom object in FXML file

 原文  2020-04-11 14:51:42  1   2    java/ javafx

問題描述

我的代碼中有以下擴展 JavaFX object ：

package shipsinspace.view.board;

import javafx.scene.shape.Rectangle;
import shipsinspace.common.Coordinates;

public class Tile extends Rectangle {
    private Coordinates coordinates;

    public Tile(double width, double height, Coordinates coordinates) {
        super(width, height);
        this.coordinates = coordinates;
    }

    public Coordinates getCoordinates() {
        return coordinates;
    }
}

它使用我寫的這個客戶 Java class 來跟蹤 Tile 位置：

package shipsinspace.common;

import java.util.Objects;

public class Coordinates {
    private int xCoordinate;
    private int yCoordinate;

    public Coordinates(int xCoordinate, int yCoordinate) {
        this(xCoordinate, yCoordinate, 10, false);
    }

    public Coordinates(int xCoordinate, int yCoordinate, int max) {
        this(xCoordinate, yCoordinate, max, false);
    }

    public Coordinates(int xCoordinate, int yCoordinate, int max, boolean allowedZero) {
        if (allowedZero) {
            if ((xCoordinate >= 0 && yCoordinate >= 0) && (xCoordinate <= max && yCoordinate <= max)) {
                this.xCoordinate = xCoordinate;
                this.yCoordinate = yCoordinate;
            } else {
                throw new IllegalArgumentException(String.format("Either X or Y has set to value <= 0, or > %d", max));
            }
        } else {
            if ((xCoordinate > 0 && yCoordinate > 0) && (xCoordinate <= max && yCoordinate <= max)) {
                this.xCoordinate = xCoordinate;
                this.yCoordinate = yCoordinate;
            } else {
                throw new IllegalArgumentException(String.format("Either X or Y has set to value <= 0, or > %d", max));
            }
        }

    }

    public int getX() {
        return xCoordinate;
    }

    public int getY() {
        return yCoordinate;
    }

    public Coordinates returnNeighbour(int axis, int direction) {
        if (axis == 0) {
            try {
                return new Coordinates(this.getX() + direction, this.getY());
            } catch (IllegalArgumentException e) {
                return new Coordinates(this.getX(), this.getY());
            }

        } else {
            try {
                return new Coordinates(this.getX(), this.getY() + direction);
            } catch (IllegalArgumentException e) {
                return new Coordinates(this.getX(), this.getY());
            }

        }
    }

    @Override
    public boolean equals(Object o) {
        if (this == o) return true;
        if (o == null || getClass() != o.getClass()) return false;
        Coordinates that = (Coordinates) o;
        return xCoordinate == that.xCoordinate &&
                yCoordinate == that.yCoordinate;
    }

    @Override
    public int hashCode() {
        return Objects.hash(xCoordinate, yCoordinate);
    }

    @Override
    public String toString() {
        return String.format("Coordinates (%d, %d)", xCoordinate, yCoordinate);
    }
}

現在，我想構建一個場景（通過 JavaFX 場景生成器），它使用 GridPane，每個單元格中都有一個 TILE object。 我決定首先在 Scene Builder 中構建一個場景，使用 JavaFX 矩形對象而不是 Tiles，然后手動編輯 .fxml 文件並將其中的 Rectangle 更改為 Tile 對象。 問題是，Intellij 現在告訴我 FXML 文件中的 Tile 對象無法實例化：

...
   <center>
      <GridPane BorderPane.alignment="CENTER">
        <columnConstraints>
            <ColumnConstraints hgrow="SOMETIMES" minWidth="10.0" prefWidth="100.0" />
            <ColumnConstraints hgrow="SOMETIMES" minWidth="10.0" prefWidth="100.0" />
            <ColumnConstraints hgrow="SOMETIMES" minWidth="10.0" prefWidth="100.0" />
            <ColumnConstraints hgrow="SOMETIMES" minWidth="10.0" prefWidth="100.0" />
            <ColumnConstraints hgrow="SOMETIMES" minWidth="10.0" prefWidth="100.0" />
            <ColumnConstraints hgrow="SOMETIMES" minWidth="10.0" prefWidth="100.0" />
            <ColumnConstraints hgrow="SOMETIMES" minWidth="10.0" prefWidth="100.0" />
            <ColumnConstraints hgrow="SOMETIMES" minWidth="10.0" prefWidth="100.0" />
            <ColumnConstraints hgrow="SOMETIMES" minWidth="10.0" prefWidth="100.0" />
          <ColumnConstraints hgrow="SOMETIMES" minWidth="10.0" prefWidth="100.0" />
          <ColumnConstraints hgrow="SOMETIMES" minWidth="10.0" prefWidth="100.0" />
        </columnConstraints>
        <rowConstraints>
            <RowConstraints minHeight="10.0" prefHeight="30.0" vgrow="SOMETIMES" />
            <RowConstraints minHeight="10.0" prefHeight="30.0" vgrow="SOMETIMES" />
            <RowConstraints minHeight="10.0" prefHeight="30.0" vgrow="SOMETIMES" />
            <RowConstraints minHeight="10.0" prefHeight="30.0" vgrow="SOMETIMES" />
            <RowConstraints minHeight="10.0" prefHeight="30.0" vgrow="SOMETIMES" />
            <RowConstraints minHeight="10.0" prefHeight="30.0" vgrow="SOMETIMES" />
            <RowConstraints minHeight="10.0" prefHeight="30.0" vgrow="SOMETIMES" />
            <RowConstraints minHeight="10.0" prefHeight="30.0" vgrow="SOMETIMES" />
          <RowConstraints minHeight="10.0" prefHeight="30.0" vgrow="SOMETIMES" />
          <RowConstraints minHeight="10.0" prefHeight="30.0" vgrow="SOMETIMES" />
          <RowConstraints minHeight="10.0" prefHeight="30.0" vgrow="SOMETIMES" />
        </rowConstraints>
         <children>

            <Tile arcHeight="5.0" arcWidth="5.0" fill="DODGERBLUE" height="52.0" stroke="BLACK" strokeType="INSIDE" width="53.0" GridPane.halignment="CENTER" GridPane.valignment="CENTER">
               <GridPane.margin>
                  <Insets bottom="1.0" left="1.0" right="1.0" top="1.0" />
               </GridPane.margin>
            </Tile>
...

我可以說，這是因為我的 Tile object 需要將坐標 object 傳遞到其構造函數中，而不是高度和寬度，但我不知道如何將它們粘貼到 FXML 代碼中。 任何幫助將不勝感激。

2 個解決方案

解決方案1
 1 已采納  2020-04-11 16:38:45

要允許FXMLLoader實例化沒有無參數構造函數的類，您需要注釋構造函數參數。 （原因是在 Java 中，參數名稱不保證在運行時保留，因此需要一種機制在運行時根據名稱反射性地將無序值與參數匹配。）請參閱javaFX 中 @NamedArg 注釋的目的是什么8？ 了解更多信息。

所以你的Tile和Coordinates類現在看起來像：

import javafx.beans.NamedArg;
import javafx.scene.shape.Rectangle;

public class Tile extends Rectangle {
    private Coordinates coordinates;

    public Tile(
            @NamedArg("width") double width,
            @NamedArg("height") double height,
            @NamedArg("coordinates") Coordinates coordinates) {
        super(width, height);
        this.coordinates = coordinates;
    }

    public Coordinates getCoordinates() {
        return coordinates;
    }
}

import java.util.Objects;

import javafx.beans.NamedArg;

public class Coordinates {
    private int xCoordinate;
    private int yCoordinate;

    public Coordinates(
            @NamedArg("xCoordinate") int xCoordinate,
            @NamedArg("yCoordinate") int yCoordinate) {
        this(xCoordinate, yCoordinate, 10, false);
    }

    public Coordinates(
            @NamedArg("xCoordinate") int xCoordinate, 
            @NamedArg("yCoordinate") int yCoordinate,
            @NamedArg("max") int max) {
        this(xCoordinate, yCoordinate, max, false);
    }

    public Coordinates(
            @NamedArg("xCoordinate") int xCoordinate,
            @NamedArg("yCoordinate") int yCoordinate,
            @NamedArg("max") int max,
            @NamedArg("allowedZero") boolean allowedZero) {
        if (allowedZero) {
            if ((xCoordinate >= 0 && yCoordinate >= 0) && (xCoordinate <= max && yCoordinate <= max)) {
                this.xCoordinate = xCoordinate;
                this.yCoordinate = yCoordinate;
            } else {
                throw new IllegalArgumentException(String.format("Either X or Y has set to value <= 0, or > %d", max));
            }
        } else {
            if ((xCoordinate > 0 && yCoordinate > 0) && (xCoordinate <= max && yCoordinate <= max)) {
                this.xCoordinate = xCoordinate;
                this.yCoordinate = yCoordinate;
            } else {
                throw new IllegalArgumentException(String.format("Either X or Y has set to value <= 0, or > %d", max));
            }
        }

    }

    // remaining code unaltered...
}

要在 FXML 中使用它，您可以執行以下操作：

<Tile width="100.0" height="100.0">
    <coordinates>
        <Coordinates xCoordinate="1" yCoordinate="1"/>
    </coordinates>
</Tile>

或者

<fx:define>
    <Coordinates fx:id="tileCoordinates" xCoordinate="1" yCoordinate="1" />
</fx:define>
<Tile width="100.0" height="100.0" coordinates="$tileCoordinates" />

這些之間的選擇大多只是風格的選擇； 但是請注意，后一個選項使您有機會讓多個Tile共享相同的Coordinates實例（可能不適用於此特定用例，但通常它很有用）。

解決方案2
 0  2020-04-11 14:58:55

您可以通過 Java 代碼添加組件。

命名您的組件以使用代碼訪問它們。

public class App {
    @FXML GridPane examplePane;

    public void initialize() {
        Tile t = new Tile();
        examplePane.add(t);
        ...
    }
}

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