我试图让两个不同的选择框同时工作,但是我在initialize方法中得到一个nullpointer错误。这有点奇怪,因为我正在尝试初始化选择框中的内容,但IDE却给了我一个nullpointer异常。
这是我的密码
package application;
import java.net.URL;
import java.util.ArrayList;
import java.util.Iterator;
import java.util.ResourceBundle;
import javafx.event.ActionEvent;
import javafx.fxml.FXML;
import javafx.fxml.FXMLLoader;
import javafx.fxml.Initializable;
import javafx.scene.Scene;
import javafx.scene.control.Button;
import javafx.scene.control.ChoiceBox;
import javafx.scene.control.Label;
import javafx.scene.control.ListView;
import javafx.scene.control.TextField;
import javafx.scene.layout.VBox;
import javafx.scene.Parent;
import javafx.stage.Stage;
public class SampleController implements Initializable{
public static piece PieceClicked = new piece();
ArrayList <Integer> possibleMoves = new ArrayList <Integer>();
ListView<Integer> listView = new ListView<Integer>();
private int enemyLocation;
private boolean valid = true;
@FXML
ChoiceBox<String> inputPieceType, inputPieceAllience;
String[] pieces = {"CANNON","CHARIOT","ELAPHANT","GENERAL","GUARD","HORSES","SOLDIERS"};
String[] allience = {"GREEN","RED"};
@Override
public void initialize(URL arg0, ResourceBundle arg1) {
inputPieceType.getItems().addAll(pieces);
inputPieceAllience.getItems().addAll(allience);
inputPieceType.setOnAction(this::setPiece);
inputPieceAllience.setOnAction(this::setAllience);
}
public void setPiece(ActionEvent event) {
PieceClicked.setPieceType(inputPieceType.getValue());
}
public void setAllience(ActionEvent event) {
PieceClicked.setPieceAllience(inputPieceAllience.getValue());
}
}
它还告诉我,在父根=fxmlLoader.load(getClass().getResource(“sample.fxml”));
处的主类中有一个错误
package application;
import javafx.application.Application;
import javafx.stage.Stage;
import javafx.scene.Scene;
import javafx.fxml.FXMLLoader;
import javafx.scene.Parent;
public class Main extends Application {
@Override
public void start(Stage primaryStage) throws Exception{
Parent root = FXMLLoader.load(getClass().getResource("Sample.fxml"));
Scene scene = new Scene(root, 600, 400);
primaryStage.setScene(scene);
primaryStage.show();
}
public static void main(String[] args) {
launch(args);
}
}
Exception in Application start method
java.lang.reflect.InvocationTargetException
at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
at java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.base/java.lang.reflect.Method.invoke(Method.java:564)
at javafx.graphics/com.sun.javafx.application.LauncherImpl.launchApplicationWithArgs(LauncherImpl.java:464)
at javafx.graphics/com.sun.javafx.application.LauncherImpl.launchApplication(LauncherImpl.java:363)
at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
at java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.base/java.lang.reflect.Method.invoke(Method.java:564)
at java.base/sun.launcher.LauncherHelper$FXHelper.main(LauncherHelper.java:1051)
Caused by: java.lang.RuntimeException: Exception in Application start method
at javafx.graphics/com.sun.javafx.application.LauncherImpl.launchApplication1(LauncherImpl.java:900)
at javafx.graphics/com.sun.javafx.application.LauncherImpl.lambda$launchApplication$2(LauncherImpl.java:195)
at java.base/java.lang.Thread.run(Thread.java:832)
Caused by: javafx.fxml.LoadException:
/Users/owenpark/eclipse/java-2020-06/Eclipse.app/Contents/MacOS/computerIA/computerScienceIA/bin/application/Sample.fxml
at javafx.fxml/javafx.fxml.FXMLLoader.constructLoadException(FXMLLoader.java:2707)
at javafx.fxml/javafx.fxml.FXMLLoader.loadImpl(FXMLLoader.java:2677)
at javafx.fxml/javafx.fxml.FXMLLoader.loadImpl(FXMLLoader.java:2548)
at javafx.fxml/javafx.fxml.FXMLLoader.loadImpl(FXMLLoader.java:3323)
at javafx.fxml/javafx.fxml.FXMLLoader.loadImpl(FXMLLoader.java:3280)
at javafx.fxml/javafx.fxml.FXMLLoader.loadImpl(FXMLLoader.java:3249)
at javafx.fxml/javafx.fxml.FXMLLoader.loadImpl(FXMLLoader.java:3222)
at javafx.fxml/javafx.fxml.FXMLLoader.loadImpl(FXMLLoader.java:3199)
at javafx.fxml/javafx.fxml.FXMLLoader.load(FXMLLoader.java:3192)
at application.Main.start(Main.java:13)
at javafx.graphics/com.sun.javafx.application.LauncherImpl.lambda$launchApplication1$9(LauncherImpl.java:846)
at javafx.graphics/com.sun.javafx.application.PlatformImpl.lambda$runAndWait$12(PlatformImpl.java:455)
at javafx.graphics/com.sun.javafx.application.PlatformImpl.lambda$runLater$10(PlatformImpl.java:428)
at java.base/java.security.AccessController.doPrivileged(AccessController.java:391)
at javafx.graphics/com.sun.javafx.application.PlatformImpl.lambda$runLater$11(PlatformImpl.java:427)
at javafx.graphics/com.sun.glass.ui.InvokeLaterDispatcher$Future.run(InvokeLaterDispatcher.java:96)
Caused by: java.lang.reflect.InvocationTargetException
at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
at java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.base/java.lang.reflect.Method.invoke(Method.java:564)
at com.sun.javafx.reflect.Trampoline.invoke(MethodUtil.java:76)
at jdk.internal.reflect.GeneratedMethodAccessor2.invoke(Unknown Source)
at java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.base/java.lang.reflect.Method.invoke(Method.java:564)
at javafx.base/com.sun.javafx.reflect.MethodUtil.invoke(MethodUtil.java:273)
at javafx.fxml/com.sun.javafx.fxml.MethodHelper.invoke(MethodHelper.java:83)
at javafx.fxml/javafx.fxml.FXMLLoader.loadImpl(FXMLLoader.java:2673)
... 14 more
Caused by: java.lang.NullPointerException
at application.SampleController.initialize(SampleController.java:62)
... 25 more
Exception running application application.Main
<?xml version="1.0" encoding="UTF-8"?>
<?import javafx.scene.control.Button?>
<?import javafx.scene.control.ChoiceBox?>
<?import javafx.scene.control.Label?>
<?import javafx.scene.control.ListView?>
<?import javafx.scene.control.TextField?>
<?import javafx.scene.image.Image?>
<?import javafx.scene.image.ImageView?>
<?import javafx.scene.layout.AnchorPane?>
<?import javafx.scene.layout.VBox?>
<?import javafx.scene.text.Text?>
<AnchorPane prefHeight="403.0" prefWidth="839.0" xmlns="http://javafx.com/javafx/15.0.1" xmlns:fx="http://javafx.com/fxml/1" fx:controller="application.SampleController">
<children>
<AnchorPane layoutX="1.0" layoutY="2.0" maxHeight="-Infinity" maxWidth="-Infinity" minHeight="-Infinity" minWidth="-Infinity" prefHeight="400.0" prefWidth="837.0">
<children>
<ImageView fitHeight="310.0" fitWidth="312.0" layoutX="14.0" layoutY="45.0">
<image>
<Image url="@../../../../../../../../../Documents/computer%20science%20IA%20photos/thumb-data_illust_Jang_Gi_Pan_1440x1440.jpeg" />
</image>
</ImageView>
<VBox layoutX="443.0" layoutY="43.0" prefHeight="315.0" prefWidth="146.0">
<children>
<Text strokeType="OUTSIDE" strokeWidth="0.0" text="location: " />
<TextField fx:id="input" />
<Text strokeType="OUTSIDE" strokeWidth="0.0" text="piece: " />
<ChoiceBox fx:id="inputPieceType" prefWidth="150.0" />
<Text strokeType="OUTSIDE" strokeWidth="0.0" text="Allience: " />
<ChoiceBox fx:id="inputPieceAllience" prefWidth="150.0" />
<Text strokeType="OUTSIDE" strokeWidth="0.0" text="enemy piece location: " />
<TextField fx:id="inputEnemyPieceLocation" prefHeight="32.0" prefWidth="146.0" />
</children>
</VBox>
<Button layoutX="332.0" layoutY="52.0" mnemonicParsing="false" prefHeight="27.0" prefWidth="33.0">
<graphic>
<ImageView fitHeight="22.0" fitWidth="27.0" pickOnBounds="true" preserveRatio="true">
<image>
<Image url="@../../../../../../../../../Documents/computer%20science%20IA%20photos/Green_King.png" />
</image>
</ImageView>
</graphic>
</Button>
<Button layoutX="332.0" layoutY="91.0" mnemonicParsing="false" prefHeight="27.0" prefWidth="33.0">
<graphic>
<ImageView fitHeight="22.0" fitWidth="26.0" pickOnBounds="true" preserveRatio="true">
<image>
<Image url="@../../../../../../../../../Documents/computer%20science%20IA%20photos/Green_Cha.png" />
</image>
</ImageView>
</graphic>
</Button>
<Button layoutX="332.0" layoutY="133.0" mnemonicParsing="false" prefHeight="27.0" prefWidth="33.0">
<graphic>
<ImageView fitHeight="21.0" fitWidth="25.0" pickOnBounds="true" preserveRatio="true">
<image>
<Image url="@../../../../../../../../../Documents/computer%20science%20IA%20photos/Green_Cannon.png" />
</image>
</ImageView>
</graphic>
</Button>
<Button layoutX="332.0" layoutY="171.0" mnemonicParsing="false" prefHeight="32.0" prefWidth="42.0">
<graphic>
<ImageView fitHeight="23.0" fitWidth="24.0" pickOnBounds="true" preserveRatio="true">
<image>
<Image url="@../../../../../../../../../Documents/computer%20science%20IA%20photos/green_Elephant.jpeg" />
</image>
</ImageView>
</graphic>
</Button>
<Button layoutX="332.0" layoutY="214.0" mnemonicParsing="false" prefHeight="31.0" prefWidth="42.0">
<graphic>
<ImageView fitHeight="20.0" fitWidth="37.0" pickOnBounds="true" preserveRatio="true">
<image>
<Image url="@../../../../../../../../../Documents/computer%20science%20IA%20photos/Green_Horse.png" />
</image>
</ImageView>
</graphic>
</Button>
<Button layoutX="332.0" layoutY="255.0" mnemonicParsing="false" prefHeight="33.0" prefWidth="42.0">
<graphic>
<ImageView fitHeight="20.0" fitWidth="67.0" pickOnBounds="true" preserveRatio="true">
<image>
<Image url="@../../../../../../../../../Documents/computer%20science%20IA%20photos/Green_Soldier.png" />
</image>
</ImageView>
</graphic>
</Button>
<Button layoutX="332.0" layoutY="296.0" mnemonicParsing="false" prefHeight="33.0" prefWidth="42.0">
<graphic>
<ImageView fitHeight="20.0" fitWidth="33.0" pickOnBounds="true" preserveRatio="true">
<image>
<Image url="@../../../../../../../../../Documents/computer%20science%20IA%20photos/Green_Guard.png" />
</image>
</ImageView>
</graphic>
</Button>
<Text layoutX="39.0" layoutY="56.0" strokeType="OUTSIDE" strokeWidth="0.0" text="1 2 3 4 5 6 7 8 9" wrappingWidth="270.7308011274751" />
<Text layoutX="29.0" layoutY="72.0" strokeType="OUTSIDE" strokeWidth="0.0" text="1" wrappingWidth="8.67726926690625" />
<Text layoutX="29.0" layoutY="98.0" strokeType="OUTSIDE" strokeWidth="0.0" text="2" wrappingWidth="8.67726926690625" />
<Text layoutX="29.0" layoutY="129.0" strokeType="OUTSIDE" strokeWidth="0.0" text="3" wrappingWidth="8.67726926690625" />
<Text layoutX="27.0" layoutY="157.0" strokeType="OUTSIDE" strokeWidth="0.0" text="4" wrappingWidth="8.67726926690625" />
<Text layoutX="27.0" layoutY="189.0" strokeType="OUTSIDE" strokeWidth="0.0" text="5" wrappingWidth="8.67726926690625" />
<Text layoutX="29.0" layoutY="218.0" strokeType="OUTSIDE" strokeWidth="0.0" text="6" wrappingWidth="8.67726926690625" />
<Text layoutX="29.0" layoutY="248.0" strokeType="OUTSIDE" strokeWidth="0.0" text="7" wrappingWidth="8.67726926690625" />
<Text layoutX="29.0" layoutY="279.0" strokeType="OUTSIDE" strokeWidth="0.0" text="8" wrappingWidth="8.67726926690625" />
<Text layoutX="29.0" layoutY="309.0" strokeType="OUTSIDE" strokeWidth="0.0" text="9" wrappingWidth="8.67726926690625" />
<Text layoutX="22.0" layoutY="335.0" strokeType="OUTSIDE" strokeWidth="0.0" text="10" wrappingWidth="20.65190019321369" />
<Button fx:id="enterButton" layoutX="452.0" layoutY="359.0" mnemonicParsing="false" onAction="#enterButton" text="Input" />
<Button fx:id="clear" layoutX="516.0" layoutY="359.0" mnemonicParsing="false" onAction="#clear" text="clear" />
<Text layoutX="380.0" layoutY="72.0" strokeType="OUTSIDE" strokeWidth="0.0" text="GENERAL" />
<Text layoutX="381.0" layoutY="110.0" strokeType="OUTSIDE" strokeWidth="0.0" text="CHARIOT" />
<Text layoutX="382.0" layoutY="153.0" strokeType="OUTSIDE" strokeWidth="0.0" text="CANNON" />
<Text layoutX="379.0" layoutY="189.0" strokeType="OUTSIDE" strokeWidth="0.0" text="ELEPHANT" />
<Text layoutX="382.0" layoutY="234.0" strokeType="OUTSIDE" strokeWidth="0.0" text="HORSE" />
<Text layoutX="382.0" layoutY="276.0" strokeType="OUTSIDE" strokeWidth="0.0" text="SOLDIER" />
<Text layoutX="386.0" layoutY="317.0" strokeType="OUTSIDE" strokeWidth="0.0" text="GUARD" />
<VBox layoutX="589.0" layoutY="42.0" prefHeight="317.0" prefWidth="126.0">
<children>
<Text strokeType="OUTSIDE" strokeWidth="0.0" text="location:" />
<Label fx:id="locationCheck" prefHeight="25.0" prefWidth="126.0" />
<Text strokeType="OUTSIDE" strokeWidth="0.0" text="piece Type: " />
<Label fx:id="pieceCheck" prefHeight="36.0" prefWidth="126.0" />
<Text strokeType="OUTSIDE" strokeWidth="0.0" text="Allience: " />
<Label fx:id="allianceCheck" prefHeight="31.0" prefWidth="128.0" />
<Text strokeType="OUTSIDE" strokeWidth="0.0" text="enemy piece location:" />
<Label fx:id="enemyLocationCheck" prefHeight="33.0" prefWidth="127.0" />
<Text strokeType="OUTSIDE" strokeWidth="0.0" text="error message:" wrappingWidth="123.269287109375" />
<Label fx:id="errorMessage" prefHeight="35.0" prefWidth="129.0" />
</children>
</VBox>
<Text layoutX="607.0" layoutY="28.0" strokeType="OUTSIDE" strokeWidth="0.0" text="validity check" />
<Text layoutX="723.0" layoutY="27.0" strokeType="OUTSIDE" strokeWidth="0.0" text="Possible Possition" />
<Text layoutX="710.0" layoutY="301.0" strokeType="OUTSIDE" strokeWidth="0.0" text="can this piece be taken" />
<Label fx:id="PieceTake" layoutX="708.0" layoutY="305.0" prefHeight="23.0" prefWidth="126.0" />
</children>
</AnchorPane>
<ListView fx:id="listView" layoutX="715.0" layoutY="40.0" prefHeight="248.0" prefWidth="113.0" />
<Button fx:id="exitButton" layoutX="779.0" layoutY="361.0" mnemonicParsing="false" onAction="#exitButton" prefHeight="27.0" prefWidth="47.0" text="exit" />
</children>
</AnchorPane>
sample.fxml文件是一个不同的场景,基本上它只是一个开始场景,用户可以在两个不同的场景中选择要转到的场景
<?xml version="1.0" encoding="UTF-8"?>
<?import javafx.scene.control.Button?>
<?import javafx.scene.layout.AnchorPane?>
<?import javafx.scene.text.Font?>
<?import javafx.scene.text.Text?>
<AnchorPane maxHeight="-Infinity" maxWidth="-Infinity" minHeight="-Infinity" minWidth="-Infinity" prefHeight="400.0" prefWidth="600.0" xmlns="http://javafx.com/javafx/15.0.1" xmlns:fx="http://javafx.com/fxml/1" fx:controller="application.SampleController">
<children>
<Text layoutX="143.0" layoutY="53.0" strokeType="OUTSIDE" strokeWidth="0.0" text="welcome to janggi!">
<font>
<Font size="40.0" />
</font>
</Text>
<Button fx:id="gameButton" layoutX="205.0" layoutY="85.0" mnemonicParsing="false" onAction="#gameButton" prefHeight="74.0" prefWidth="190.0" text="Game Play">
<font>
<Font size="22.0" />
</font>
</Button>
<Button fx:id="explanationButton" layoutX="205.0" layoutY="225.0" mnemonicParsing="false" onAction="#explanationButton" prefHeight="74.0" prefWidth="190.0" text="Explanation">
<font>
<Font size="22.0" />
</font>
</Button>
</children>
</AnchorPane>
编辑:实际问题是samplecontroller
链接到两个不同的.fxml
文件,并且只加载了sample.fxml
文件,该文件不包含ChoiceBox
ES。这个问题可以通过两个单独的控制器来解决,每个.fxml
文件一个控制器,并加载这两个控制器。
老答案:在JavaFX控制器中,标记有@fxml
标记的字段的值由JavaFX-runtime从与控制器关联的.fxml
文件中定义的控件中注入。
在您的示例中,控制器中有两个ChoiceBox
实例,因此您还需要在.fxml
文件中定义两个ChoiceBox
E。要允许运行库知道哪个控件要链接到控制器中的哪个字段,您需要在.fxml
文件中的每个控件上添加fx:id=“fieldname”
。不要忘记将fieldname
的值更改为控制器中字段的相应名称,在您的示例中,其中一个字段的名称为InputPieceType
,另一个字段的名称为InputPieceallience
。
.fxml
文件如下所示:
<ChoiceBox fx:id="inputPieceType" [other properties...] />
如果您不确定controller类是否连接到.fxml
文件,您可以通过查找.fxml
文件中的fx:controller=“com.example.mycontroller”
属性来了解这一点。com.example.myController
将是controller类的全名,在您的示例中,该类应该是application.sampleController
。
请注意,在加载.fxml
文件时,还可以通过调用FXMLLoader.SetController(controller);
来在代码中而不是在.fxml
中设置控制器。您使用哪一个取决于您的用例。
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