Question

在“Pro JavaFX 8：构建桌面，移动和嵌入式Java客户端的权威指南”的第3章中，说明如何直接在FXML文件中指定对象的示例在NetBeans 8.0.2中生成错误（我下载了来自本书网站的代码和我迄今为止尝试过的所有其他例子。

此FXML代码段：

<discount>
        <Utilities fx:constant="TEN_PCT"/>
</discount>

应该使用Utilities.java中定义的常量discount初始化字段TEN_PCT：

package projavafx.fxmlbasicfeatures;

import java.util.ArrayList;
import java.util.List;

public class Utilities {
    public static final Double TEN_PCT = 0.1d;
    public static final Double TWENTY_PCT = 0.2d;
    public static final Double THIRTY_PCT = 0.3d;

    public static List<Integer> createList() {
        return new ArrayList<>();
    }
}

工具提示错误为“实用程序未定义常量'TEN_PCT'。”

此时出现同一示例中的另一个错误：

<profits>
    <HashMap q1="1000" q2="1100" q3="1200" a4="1300"/>
</profits>

错误“Class'java.util.HashMap'不支持属性'q1'”，其他键也有类似错误。

这些错误的原因是什么，以及如何修复？

这是所有文件（除了上面的Utilities.java）：

FXMLBasicFeatures.fxml：

<?import javafx.scene.paint.Color?>
<?import projavafx.fxmlbasicfeatures.FXMLBasicFeaturesBean?>
<?import projavafx.fxmlbasicfeatures.Utilities?>
<?import java.lang.Double?>
<?import java.lang.Integer?>
<?import java.lang.Long?>
<?import java.util.HashMap?>
<?import java.lang.String?>
<FXMLBasicFeaturesBean name="John Smith"
                       flag="true"
                       count="12345"
                       xmlns:fx="http://javafx.com/fxml/1">
    <address>12345 Main St.</address>
    <foreground>#ff8800</foreground>
    <background>
        <Color red="0.0" green="1.0" blue="0.5"/>
    </background>
    <price>
        <Double fx:value="3.1415926"/>
    </price>
    <discount>
        <Utilities fx:constant="TEN_PCT"/>
    </discount>
    <sizes>
        <Utilities fx:factory="createList">
            <Integer fx:value="1"/>
            <Integer fx:value="2"/>
            <Integer fx:value="3"/>
        </Utilities>
    </sizes>
    <profits>
        <HashMap q1="1000" q2="1100" q3="1200" a4="1300"/>
    </profits>
    <fx:define>
        <Long fx:id="inv" fx:value="9765625"/>
    </fx:define>
    <inventory>
        <fx:reference source="inv"/>
    </inventory>
    <products>
        <String fx:value="widget"/>
        <String fx:value="gadget"/>
        <String fx:value="models"/>
    </products>
    <abbreviations CA="California" NY="New York" FL="Florida" MO="Missouri"/>

</FXMLBasicFeaturesBean>

FXMLBasicFeaturesBean.java：

package projavafx.fxmlbasicfeatures;

import javafx.scene.paint.Color;

import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;

public class FXMLBasicFeaturesBean {
    private String name;
    private String address;
    private boolean flag;
    private int count;
    private Color foreground;
    private Color background;
    private Double price;
    private Double discount;
    private List<Integer> sizes;
    private Map<String, Double> profits;
    private Long inventory;
    private List<String> products = new ArrayList<String>();
    private Map<String, String> abbreviations = new HashMap<>();

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public String getAddress() {
        return address;
    }

    public void setAddress(String address) {
        this.address = address;
    }

    public boolean isFlag() {
        return flag;
    }

    public void setFlag(boolean flag) {
        this.flag = flag;
    }

    public int getCount() {
        return count;
    }

    public void setCount(int count) {
        this.count = count;
    }

    public Color getForeground() {
        return foreground;
    }

    public void setForeground(Color foreground) {
        this.foreground = foreground;
    }

    public Color getBackground() {
        return background;
    }

    public void setBackground(Color background) {
        this.background = background;
    }

    public Double getPrice() {
        return price;
    }

    public void setPrice(Double price) {
        this.price = price;
    }

    public Double getDiscount() {
        return discount;
    }

    public void setDiscount(Double discount) {
        this.discount = discount;
    }

    public List<Integer> getSizes() {
        return sizes;
    }

    public void setSizes(List<Integer> sizes) {
        this.sizes = sizes;
    }

    public Map<String, Double> getProfits() {
        return profits;
    }

    public void setProfits(Map<String, Double> profits) {
        this.profits = profits;
    }

    public Long getInventory() {
        return inventory;
    }

    public void setInventory(Long inventory) {
        this.inventory = inventory;
    }

    public List<String> getProducts() {
        return products;
    }

    public Map<String, String> getAbbreviations() {
        return abbreviations;
    }

    @Override
    public String toString() {
        return "FXMLBasicFeaturesBean{" +
            "name='" + name + '\'' +
            ",\n\taddress='" + address + '\'' +
            ",\n\tflag=" + flag +
            ",\n\tcount=" + count +
            ",\n\tforeground=" + foreground +
            ",\n\tbackground=" + background +
            ",\n\tprice=" + price +
            ",\n\tdiscount=" + discount +
            ",\n\tsizes=" + sizes +
            ",\n\tprofits=" + profits +
            ",\n\tinventory=" + inventory +
            ",\n\tproducts=" + products +
            ",\n\tabbreviations=" + abbreviations +
            '}';
    }
}

FXMLBasicFeaturesMain.java：

package projavafx.fxmlbasicfeatures;

import javafx.fxml.FXMLLoader;

import java.io.IOException;

public class FXMLBasicFeaturesMain {
    public static void main(String[] args) throws IOException {
        FXMLBasicFeaturesBean bean = FXMLLoader.load(
            FXMLBasicFeaturesMain.class.getResource(
                "/projavafx/fxmlbasicfeatures/FXMLBasicFeatures.fxml")
        );
        System.out.println("bean = " + bean);
    }
}

Answer 1

您在NetBeans编辑器中看到的两个错误都是由NetBeans本身的错误引起的。这只是NetBeans编辑器中的一个问题，在运行示例应用程序时，FXMLLoader将很乐意处理这些语句，如您所知。

发生第一个错误是因为NetBeans似乎不允许类型与封闭类类型不同的常量字段。所以下面的代码片段将起作用，因为常量Double.POSITIVE_INFINITY本身是一个双精度：

<discount>
    <Double fx:constant="POSITIVE_INFINITY"/>
</discount>

发生第二个错误是因为NetBeans编辑器根本不支持映射的特殊用例。

我已经在NetBeans bugzilla中为这两个案例提交了错误报告。

没有为Utilities定义

Constant 'TEN_PCT： https://netbeans.org/bugzilla/show_bug.cgi?id=252416

Class 'java.util.HashMap' does not support property 'q1'： https://netbeans.org/bugzilla/show_bug.cgi?id=252417

NetBeans错误显示在“Pro JavaFX 8：A权威指南”一书中的示例代码中初始化FXML文件中的对象

1 个答案: