我对 JavaFx 还很陌生。我正在尝试按照教程构建一个简单的计算器。我是按照教程一步一步来的。当我运行该项目时，它显示 javafx fxml LoadException。我看了一些与此相关的解决方案，但仍然无法修复它。请帮我解决这个错误。(抱歉，帖子很长)
我的程序文件如下
MainController.java
package application;
import javafx.event.ActionEvent;
import javafx.fxml.FXML;
import javafx.scene.control.Button;
import javafx.scene.control.Label;
public class MainController {
@FXML
private Label result; // label variable shows output above the buttons, check this
private long number1 = 0;
private String operator = "";
private boolean start = true;
private Model model = new Model();
@FXML
public void processNumbers(ActionEvent event) {
if (start) {
result.setText(""); // set the label(output) screen as blank first
start = false;
}
String value = ((Button) event.getSource()).getText(); // take number 1-9 and convert it into String, import the
// button class otherwise will shows error
result.setText(result.getText() + value);
}
@FXML
public void processOperators(ActionEvent event) {
String value = ((Button) event.getSource()).getText();`enter code here`
if (!value.equals("=")) {
if (!operator.isEmpty()) {
return;
}
operator = value;
number1 = Long.parseLong(result.getText());
result.setText("");
} else {
if (operator.isEmpty())
return;
long number2 = Long.parseLong(result.getText());
float output = model.calculate(number2, number2, operator);
result.setText(String.valueOf(output));
start = true;
}
}
}
模型.java
package application;
public class Model { //for some action event
public float calculate(long number1,long number2,String operator) {
switch(operator) {
case "+":
return number1+number2;
case "-":
return number1-number2;
case "*":
return number1*number2;
case "/":
if(number2==0) return 0;
return number1+number2;
default:
return 0;
}//switch case
}
}
Main.java
package application;
import javafx.application.Application;
import javafx.fxml.FXMLLoader;
import javafx.stage.Stage;
import javafx.scene.Parent;
import javafx.scene.Scene;
import javafx.scene.layout.BorderPane;
import javafx.scene.control.*;
public class Main extends Application {
@Override
public void start(Stage primaryStage) {
try {
Parent root = (Parent) FXMLLoader.load(getClass().getResource("/application/CalculatorFxmlFile.fxml"));
Scene scene = new Scene(root,400,400);
scene.getStylesheets().add(getClass().getResource("application.css").toExternalForm());
primaryStage.setScene(scene);
primaryStage.show();
} catch(Exception e) {
e.printStackTrace();
}
}
public static void main(String[] args) {
launch(args);
}
}
CalculatorFxmlFile
<?xml version="1.0" encoding="UTF-8"?>
<?import javafx.scene.control.Button?>
<?import javafx.scene.control.Label?>
<?import javafx.scene.layout.HBox?>
<?import javafx.scene.layout.StackPane?>
<?import javafx.scene.layout.VBox?>
<?import javafx.scene.text.Font?>
<VBox maxHeight="-Infinity" maxWidth="-Infinity" minHeight="-Infinity" minWidth="-Infinity" prefHeight="300.0" prefWidth="300.0" spacing="10.0" xmlns="http://javafx.com/javafx/8.0.111" xmlns:fx="http://javafx.com/fxml/1" fx:controller="application.MainController">
<children>
<StackPane prefHeight="50.0" prefWidth="200.0">
<children>
<Label fx:id="result" prefHeight="17.0" prefWidth="327.0" text="Label">
<font>
<Font name="System Bold" size="18.0" />
</font>
</Label>
</children></StackPane>
<HBox alignment="CENTER" prefHeight="50.0" prefWidth="300.0" spacing="10.0">
<children>
<Button mnemonicParsing="false" onAction="#processNumbers" prefWidth="50.0" text="7">
<font>
<Font size="18.0" />
</font>
</Button>
<Button mnemonicParsing="false" onAction="#processNumbers" prefWidth="50.0" text="8">
<font>
<Font size="18.0" />
</font>
</Button>
<Button mnemonicParsing="false" onAction="#processNumbers" prefWidth="50.0" text="9">
<font>
<Font size="18.0" />
</font>
</Button>
<Button fx:id="result" mnemonicParsing="false" onAction="#processOperators" prefWidth="50.0" text="/">
<font>
<Font size="18.0" />
</font>
</Button>
</children>
</HBox>
<HBox alignment="CENTER" prefHeight="50.0" prefWidth="300.0" spacing="10.0">
<children>
<Button mnemonicParsing="false" onAction="#processNumbers" prefWidth="50.0" text="4">
<font>
<Font size="18.0" />
</font>
</Button>
<Button mnemonicParsing="false" onAction="#processNumbers" prefWidth="50.0" text="5">
<font>
<Font size="18.0" />
</font>
</Button>
<Button mnemonicParsing="false" onAction="#processNumbers" prefWidth="50.0" text="6">
<font>
<Font size="18.0" />
</font>
</Button>
<Button mnemonicParsing="false" onAction="#processOperators" prefWidth="50.0" text="*">
<font>
<Font size="18.0" />
</font>
</Button>
</children>
</HBox>
<HBox alignment="CENTER" prefHeight="50.0" prefWidth="300.0" spacing="10.0">
<children>
<Button mnemonicParsing="false" onAction="#processNumbers" prefWidth="50.0" text="1">
<font>
<Font size="18.0" />
</font>
</Button>
<Button mnemonicParsing="false" onAction="#processNumbers" prefWidth="50.0" text="2">
<font>
<Font size="18.0" />
</font>
</Button>
<Button mnemonicParsing="false" onAction="#processNumbers" prefWidth="50.0" text="3">
<font>
<Font size="18.0" />
</font>
</Button>
<Button mnemonicParsing="false" onAction="#processOperators" prefWidth="50.0" text="-">
<font>
<Font size="18.0" />
</font>
</Button>
</children>
</HBox>
<HBox alignment="CENTER" prefHeight="50.0" prefWidth="300.0" spacing="10.0">
<children>
<Button mnemonicParsing="false" onAction="#processNumbers" prefWidth="110.0" text="0">
<font>
<Font size="18.0" />
</font>
</Button>
<Button mnemonicParsing="false" onAction="#processOperators" prefWidth="50.0" text="=">
<font>
<Font size="18.0" />
</font>
</Button>
<Button mnemonicParsing="false" onAction="#processOperators" prefWidth="50.0" text="+">
<font>
<Font size="18.0" />
</font>
</Button>
</children>
</HBox>
</children>
</VBox>
生成异常
javafx.fxml.LoadException:
/C:/AllPrograms/Java/eclipse1/CalculatorJavaFx/bin/application/CalculatorFxmlFile.fxml:37
at javafx.fxml.FXMLLoader.constructLoadException(FXMLLoader.java:2601)
at javafx.fxml.FXMLLoader.loadImpl(FXMLLoader.java:2579)
at javafx.fxml.FXMLLoader.loadImpl(FXMLLoader.java:2441)
at javafx.fxml.FXMLLoader.loadImpl(FXMLLoader.java:3214)
at javafx.fxml.FXMLLoader.loadImpl(FXMLLoader.java:3175)
at javafx.fxml.FXMLLoader.loadImpl(FXMLLoader.java:3148)
at javafx.fxml.FXMLLoader.loadImpl(FXMLLoader.java:3124)
at javafx.fxml.FXMLLoader.loadImpl(FXMLLoader.java:3104)
at javafx.fxml.FXMLLoader.load(FXMLLoader.java:3097)
at application.Main.start(Main.java:15)
at com.sun.javafx.application.LauncherImpl.lambda$launchApplication1$162(LauncherImpl.java:863)
at com.sun.javafx.application.PlatformImpl.lambda$runAndWait$175(PlatformImpl.java:326)
at com.sun.javafx.application.PlatformImpl.lambda$null$173(PlatformImpl.java:295)
at java.security.AccessController.doPrivileged(Native Method)
at com.sun.javafx.application.PlatformImpl.lambda$runLater$174(PlatformImpl.java:294)
at com.sun.glass.ui.InvokeLaterDispatcher$Future.run(InvokeLaterDispatcher.java:95)
at com.sun.glass.ui.win.WinApplication._runLoop(Native Method)
at com.sun.glass.ui.win.WinApplication.lambda$null$148(WinApplication.java:191)
at java.lang.Thread.run(Unknown Source)
Caused by: java.lang.IllegalArgumentException: Can not set javafx.scene.control.Label field application.MainController.result to javafx.scene.control.Button
at sun.reflect.UnsafeFieldAccessorImpl.throwSetIllegalArgumentException(Unknown Source)
at sun.reflect.UnsafeFieldAccessorImpl.throwSetIllegalArgumentException(Unknown Source)
at sun.reflect.UnsafeObjectFieldAccessorImpl.set(Unknown Source)
at java.lang.reflect.Field.set(Unknown Source)
at javafx.fxml.FXMLLoader.injectFields(FXMLLoader.java:1163)
at javafx.fxml.FXMLLoader.access$1600(FXMLLoader.java:103)
at javafx.fxml.FXMLLoader$ValueElement.processValue(FXMLLoader.java:857)
at javafx.fxml.FXMLLoader$ValueElement.processStartElement(FXMLLoader.java:751)
at javafx.fxml.FXMLLoader.processStartElement(FXMLLoader.java:2707)
at javafx.fxml.FXMLLoader.loadImpl(FXMLLoader.java:2527)
... 17 more
最佳答案
这是您的错误(在您的 fxml 文件中):
<Button fx:id="result" mnemonicParsing="false" onAction="#processOperators" prefWidth="50.0" text="/">
<font>
<Font size="18.0" />
</font>
</Button>
此按钮id是“结果”，也是标签的id。您应该删除此 id 属性(我认为您放错了它)或将其更改为教程建议的属性。
更新
此操作是除法，但您要添加数字 number1 和 number2
case "/":
if(number2==0) return 0;
return number1+number2;
所以你应该执行除法而不是加法
case "/":
if(number2==0) return 0;
return number1/number2;
更新2
我发现的另一个错误也在这里:
float output = model.calculate(number2, number2, operator);
您错过了 calculate 方法中的 number1 变量:
float output = model.calculate(number1, number2, operator);
关于javafx fxml LoadException，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/46265719/