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，一个示例说明了如何直接在 FXML 文件中指定对象在 NetBeans 8.0.2 中生成错误(我下载了本书网站上的代码以及我迄今为止尝试过的所有其他示例都有效)。
此 FXML 片段:
<discount>
<Utilities fx:constant="TEN_PCT"/>
</discount>
应该使用 Utilities.java 中定义的常量 TEN_PCT 初始化字段 discount:
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“未为实用程序定义常量‘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>
出现错误“Class 'java.util.HashMap' does not support property 'q1'”，其他键也出现类似错误。
这些错误的原因是什么？如何修复这些错误？
这是所有文件(除了上面的 Utilities.java 之外):
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);
}
}
最佳答案
您在 NetBeans 编辑器中看到的两个错误都是由于 NetBeans 本身的错误造成的。这只是 NetBeans 编辑器中的一个问题，在运行示例应用程序时，FXMLLoader 将愉快地处理这些语句，就像您自己注意到的那样。
发生第一个错误是因为 NetBeans 似乎不允许常量字段的类型与封闭类的类型不同。因此，以下代码片段将起作用，因为常量 Double.POSITIVE_INFINITY 本身就是一个 double:
<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 中提交了这两种情况的错误报告。
未为实用程序定义常量“TEN_PCT”:
https://netbeans.org/bugzilla/show_bug.cgi?id=252416
类“java.util.HashMap”不支持属性“q1”:
https://netbeans.org/bugzilla/show_bug.cgi?id=252417
关于java - NetBeans 错误显示在书籍 "Pro JavaFX 8: A Definitive Guide"初始化 FXML 文件中的对象中的示例代码中，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/30252185/