Intellij Idea 我收到“线程“JavaFX应用程序线程”java.lang.RuntimeException“中的异常：我的JavaFX应用程序中出现“java.lang.reflect.InvocationTargetException”错误

guykilcj  于 2023-01-29  发布在  Java
关注(0)|答案(1)|浏览(383)

这就是错误。

Exception in thread "JavaFX Application Thread" java.lang.RuntimeException: java.lang.reflect.InvocationTargetException
    at javafx.fxml@19-ea/javafx.fxml.FXMLLoader$MethodHandler.invoke(FXMLLoader.java:1857)
    at javafx.fxml@19-ea/javafx.fxml.FXMLLoader$ControllerMethodEventHandler.handle(FXMLLoader.java:1724)
    at javafx.base@19-ea/com.sun.javafx.event.CompositeEventHandler.dispatchBubblingEvent(CompositeEventHandler.java:86)
    at javafx.base@19-ea/com.sun.javafx.event.EventHandlerManager.dispatchBubblingEvent(EventHandlerManager.java:234)
    at javafx.base@19-ea/com.sun.javafx.event.EventHandlerManager.dispatchBubblingEvent(EventHandlerManager.java:191)
    at javafx.base@19-ea/com.sun.javafx.event.CompositeEventDispatcher.dispatchBubblingEvent(CompositeEventDispatcher.java:59)
    at javafx.base@19-ea/com.sun.javafx.event.BasicEventDispatcher.dispatchEvent(BasicEventDispatcher.java:58)
    at javafx.base@19-ea/com.sun.javafx.event.EventDispatchChainImpl.dispatchEvent(EventDispatchChainImpl.java:114)
    at javafx.base@19-ea/com.sun.javafx.event.BasicEventDispatcher.dispatchEvent(BasicEventDispatcher.java:56)
    at javafx.base@19-ea/com.sun.javafx.event.EventDispatchChainImpl.dispatchEvent(EventDispatchChainImpl.java:114)
    at javafx.base@19-ea/com.sun.javafx.event.BasicEventDispatcher.dispatchEvent(BasicEventDispatcher.java:56)
    at javafx.base@19-ea/com.sun.javafx.event.EventDispatchChainImpl.dispatchEvent(EventDispatchChainImpl.java:114)
    at javafx.base@19-ea/com.sun.javafx.event.EventUtil.fireEventImpl(EventUtil.java:74)
    at javafx.base@19-ea/com.sun.javafx.event.EventUtil.fireEvent(EventUtil.java:49)
    at javafx.base@19-ea/javafx.event.Event.fireEvent(Event.java:198)
    at javafx.graphics@19-ea/javafx.scene.Node.fireEvent(Node.java:8797)
    at javafx.controls@19-ea/javafx.scene.control.Button.fire(Button.java:203)
    at javafx.controls@19-ea/com.sun.javafx.scene.control.behavior.ButtonBehavior.mouseReleased(ButtonBehavior.java:208)
    at javafx.controls@19-ea/com.sun.javafx.scene.control.inputmap.InputMap.handle(InputMap.java:274)
    at javafx.base@19-ea/com.sun.javafx.event.CompositeEventHandler$NormalEventHandlerRecord.handleBubblingEvent(CompositeEventHandler.java:247)
    at javafx.base@19-ea/com.sun.javafx.event.CompositeEventHandler.dispatchBubblingEvent(CompositeEventHandler.java:80)
    at javafx.base@19-ea/com.sun.javafx.event.EventHandlerManager.dispatchBubblingEvent(EventHandlerManager.java:234)
    at javafx.base@19-ea/com.sun.javafx.event.EventHandlerManager.dispatchBubblingEvent(EventHandlerManager.java:191)
    at javafx.base@19-ea/com.sun.javafx.event.CompositeEventDispatcher.dispatchBubblingEvent(CompositeEventDispatcher.java:59)
    at javafx.base@19-ea/com.sun.javafx.event.BasicEventDispatcher.dispatchEvent(BasicEventDispatcher.java:58)
    at javafx.base@19-ea/com.sun.javafx.event.EventDispatchChainImpl.dispatchEvent(EventDispatchChainImpl.java:114)
    at javafx.base@19-ea/com.sun.javafx.event.BasicEventDispatcher.dispatchEvent(BasicEventDispatcher.java:56)
    at javafx.base@19-ea/com.sun.javafx.event.EventDispatchChainImpl.dispatchEvent(EventDispatchChainImpl.java:114)
    at javafx.base@19-ea/com.sun.javafx.event.BasicEventDispatcher.dispatchEvent(BasicEventDispatcher.java:56)
    at javafx.base@19-ea/com.sun.javafx.event.EventDispatchChainImpl.dispatchEvent(EventDispatchChainImpl.java:114)
    at javafx.base@19-ea/com.sun.javafx.event.EventUtil.fireEventImpl(EventUtil.java:74)
    at javafx.base@19-ea/com.sun.javafx.event.EventUtil.fireEvent(EventUtil.java:54)
    at javafx.base@19-ea/javafx.event.Event.fireEvent(Event.java:198)
    at javafx.graphics@19-ea/javafx.scene.Scene$MouseHandler.process(Scene.java:3881)
    at javafx.graphics@19-ea/javafx.scene.Scene.processMouseEvent(Scene.java:1874)
    at javafx.graphics@19-ea/javafx.scene.Scene$ScenePeerListener.mouseEvent(Scene.java:2607)
    at javafx.graphics@19-ea/com.sun.javafx.tk.quantum.GlassViewEventHandler$MouseEventNotification.run(GlassViewEventHandler.java:411)
    at javafx.graphics@19-ea/com.sun.javafx.tk.quantum.GlassViewEventHandler$MouseEventNotification.run(GlassViewEventHandler.java:301)
    at java.base/java.security.AccessController.doPrivileged(AccessController.java:399)
    at javafx.graphics@19-ea/com.sun.javafx.tk.quantum.GlassViewEventHandler.lambda$handleMouseEvent$2(GlassViewEventHandler.java:450)
    at javafx.graphics@19-ea/com.sun.javafx.tk.quantum.QuantumToolkit.runWithoutRenderLock(QuantumToolkit.java:424)
    at javafx.graphics@19-ea/com.sun.javafx.tk.quantum.GlassViewEventHandler.handleMouseEvent(GlassViewEventHandler.java:449)
    at javafx.graphics@19-ea/com.sun.glass.ui.View.handleMouseEvent(View.java:551)
    at javafx.graphics@19-ea/com.sun.glass.ui.View.notifyMouse(View.java:937)
    at javafx.graphics@19-ea/com.sun.glass.ui.win.WinApplication._runLoop(Native Method)
    at javafx.graphics@19-ea/com.sun.glass.ui.win.WinApplication.lambda$runLoop$3(WinApplication.java:184)
    at java.base/java.lang.Thread.run(Thread.java:1589)
Caused by: java.lang.reflect.InvocationTargetException
    at java.base/jdk.internal.reflect.DirectMethodHandleAccessor.invoke(DirectMethodHandleAccessor.java:119)
    at java.base/java.lang.reflect.Method.invoke(Method.java:578)
    at com.sun.javafx.reflect.Trampoline.invoke(MethodUtil.java:77)
    at java.base/jdk.internal.reflect.DirectMethodHandleAccessor.invoke(DirectMethodHandleAccessor.java:104)
    at java.base/java.lang.reflect.Method.invoke(Method.java:578)
    at javafx.base@19-ea/com.sun.javafx.reflect.MethodUtil.invoke(MethodUtil.java:275)
    at javafx.fxml@19-ea/com.sun.javafx.fxml.MethodHelper.invoke(MethodHelper.java:84)
    at javafx.fxml@19-ea/javafx.fxml.FXMLLoader$MethodHandler.invoke(FXMLLoader.java:1852)
    ... 46 more
Caused by: java.lang.NumberFormatException: For input string: ""
    at java.base/java.lang.NumberFormatException.forInputString(NumberFormatException.java:67)
    at java.base/java.lang.Integer.parseInt(Integer.java:675)
    at java.base/java.lang.Integer.valueOf(Integer.java:992)
    at com.example.studentdatabase/com.example.studentdatabase.Register.register(Register.java:99)
    at java.base/jdk.internal.reflect.DirectMethodHandleAccessor.invoke(DirectMethodHandleAccessor.java:104)
    ... 53 more

这些是我的类和FXML
Main类-

package com.example.studentdatabase;

import javafx.application.Application;
import javafx.fxml.FXMLLoader;
import javafx.scene.Scene;
import javafx.scene.image.Image;
import javafx.stage.Stage;

import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.IOException;
import java.io.InputStream;

public class Main extends Application {

    InputStream stream = new FileInputStream("C:\\Users\\dinira francisco\\Desktop\\DDSlogo.jpg");
    Image image  = new Image(stream);

    public Main() throws FileNotFoundException {
    }

    @Override
    public void start(Stage stage) throws IOException {
        FXMLLoader fxmlLoader = new FXMLLoader(Main.class.getResource("Register.fxml"));
        Scene scene = new Scene(fxmlLoader.load());
        stage.setTitle("Student Database 2023");
        stage.getIcons().add(image);
        stage.setResizable(false);
        stage.setScene(scene);
        stage.show();
    }

    public static void main(String[] args) {
        launch();
    }
}
// type here

Register类-

package com.example.studentdatabase;

import javafx.event.ActionEvent;
import javafx.fxml.FXML;
import javafx.scene.control.Button;
import javafx.scene.control.Label;
import javafx.scene.control.TextField;
import javafx.scene.image.Image;

import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.InputStream;
import java.sql.Connection;
import java.sql.Statement;

public class Register {
    private int studentID=0;

    private boolean hasFirstName = false;
    private boolean hasLastName = false;
    private boolean hasAge = false;
    private boolean hasGrade = false;
    @FXML
    private TextField GradeTF;

    @FXML
    private Button ageSubmit;

    @FXML
    private TextField ageTF;

    @FXML
    private TextField firstNameTF;

    @FXML
    private Button firstSubmit;

    @FXML
    private Button gradeSubmit;

    @FXML
    private TextField lastNameTF;

    @FXML
    private Button lastsubmit;

    @FXML
    private Button registerButton;

    @FXML
    private Label warning;

    public void getFirstName(ActionEvent event){
        if(firstNameTF.getText().length()>=1){
            hasFirstName=true;
            firstNameTF.setDisable(true);
        }
    }

    public void getLastName(ActionEvent event){
        if(lastNameTF.getText().length()>=1){
            hasLastName=true;
            lastNameTF.setDisable(true);
        }
    }

    public void getAge(ActionEvent event){
        if(ageTF.getText().length()>=1){
            hasAge=true;
            ageTF.setDisable(true);
        }
    }

    public void getGrade(ActionEvent event){
        if(GradeTF.getText().length()>=1){
            hasGrade=true;
            GradeTF.setDisable(true);
        }
    }

    public void register(ActionEvent event){
        if(hasFirstName && hasLastName && hasAge && hasGrade){
            studentID++;
            warning.setText("Registration Completed!");
            warning.setVisible(true);
            firstNameTF.setText("");
            lastNameTF.setText("");
            ageTF.setText("");
            GradeTF.setText("");
            firstNameTF.setDisable(false);
            lastNameTF.setDisable(false);
            ageTF.setDisable(false);
            GradeTF.setDisable(false);
            hasFirstName=false;
            hasLastName = false;
            hasAge = false;
            hasGrade = false;
            DatabaseConnection databaseConnection = new DatabaseConnection();
            Connection connection = databaseConnection.getConnection();

            String registerString = "INSERT INTO student_data(student_id,first_name,last_name,age,grade) VALUES('"+studentID+"','"+firstNameTF.getText()+"','"+lastNameTF.getText()+"','"+Integer.valueOf(ageTF.getText())+"','"+Integer.valueOf(GradeTF.getText())+"')";
            try{
                Statement statement = connection.createStatement();
                statement.executeUpdate(registerString);
            }catch(Exception e){
                e.printStackTrace();
                e.getCause();
            }
        }else{
            warning.setText("Fields are Empty!");
            warning.setVisible(true);
        }
    }
}

数据库连接类-

package com.example.studentdatabase;

import java.sql.Connection;
import java.sql.DriverManager;

public class DatabaseConnection {
    public Connection databaseLink;

    public Connection getConnection(){
        String databaseName = "student_db";
        String databaseUser = "root";
        String databasePassword = "***";
        String url = "jdbc:mysql://localhost/"+databaseName;
        try{
            Class.forName("com.mysql.cj.jdbc.Driver");
            databaseLink = DriverManager.getConnection(url,databaseUser,databasePassword);
        }catch (Exception e){
            e.printStackTrace();
            e.getCause();
        }
        return databaseLink;
    }
}

和FXML-

<?xml version="1.0" encoding="UTF-8"?>

<?import javafx.scene.control.Button?>
<?import javafx.scene.control.Label?>
<?import javafx.scene.control.TextField?>
<?import javafx.scene.layout.AnchorPane?>
<?import javafx.scene.text.Font?>

<AnchorPane prefHeight="443.0" prefWidth="458.0" style="-fx-background-color: #f0db24;" xmlns="http://javafx.com/javafx/19" xmlns:fx="http://javafx.com/fxml/1" fx:controller="com.example.studentdatabase.Register">
   <children>
      <Label layoutX="161.0" layoutY="25.0" text="Student Database">
         <font>
            <Font size="17.0" />
         </font>
      </Label>
      <Label layoutX="95.0" layoutY="52.0" text="Sinhala Oratory &amp; Debating Society">
         <font>
            <Font size="17.0" />
         </font>
      </Label>
      <Label layoutX="106.0" layoutY="78.0" text="D.S.Senanayake College - Col. 08">
         <font>
            <Font size="17.0" />
         </font>
      </Label>
      <Label layoutX="161.0" layoutY="125.0" text="Registration Form">
         <font>
            <Font size="17.0" />
         </font>
      </Label>
      <Label layoutX="66.0" layoutY="177.0" text="First Name ">
         <font>
            <Font size="15.0" />
         </font>
      </Label>
      <Label layoutX="67.0" layoutY="226.0" text="Last Name ">
         <font>
            <Font size="15.0" />
         </font>
      </Label>
      <Label layoutX="66.0" layoutY="269.0" text="Age">
         <font>
            <Font size="15.0" />
         </font>
      </Label>
      <Label layoutX="66.0" layoutY="315.0" text="Grade">
         <font>
            <Font size="15.0" />
         </font>
      </Label>
      <TextField fx:id="firstNameTF" layoutX="154.0" layoutY="175.0" />
      <TextField fx:id="lastNameTF" layoutX="154.0" layoutY="224.0" />
      <TextField fx:id="ageTF" layoutX="154.0" layoutY="267.0" />
      <TextField fx:id="GradeTF" layoutX="154.0" layoutY="313.0" />
      <Button fx:id="firstSubmit" layoutX="318.0" layoutY="175.0" mnemonicParsing="false" onAction="#getFirstName" text="Submit" />
      <Button fx:id="gradeSubmit" layoutX="318.0" layoutY="313.0" mnemonicParsing="false" onAction="#getGrade" text="Submit" />
      <Button fx:id="ageSubmit" layoutX="318.0" layoutY="267.0" mnemonicParsing="false" onAction="#getAge" text="Submit" />
      <Button fx:id="lastsubmit" layoutX="318.0" layoutY="224.0" mnemonicParsing="false" onAction="#getLastName" text="Submit" />
      <Button fx:id="registerButton" layoutX="192.0" layoutY="358.0" mnemonicParsing="false" onAction="#register" text="Register" />
      <Label fx:id="warning" layoutX="175.0" layoutY="399.0" text="Fields are Empty!" textFill="#f70909" visible="false" />
   </children>
</AnchorPane>

我在stackoverflow中搜索了一些解决方案，但无法解决这个问题。

intellij-idea

1条答案

按热度按时间
8hhllhi2

8hhllhi21#

首先是关于代码的一些注解。

类DatabaseConnection
Class.forName("com.mysql.cj.jdbc.Driver");

这是no longer needed。
因为方法getConnection中的catch块，该方法可能返回null，这意味着调用方法getConnection的其他方法需要检查是否返回null。在我看来，最好声明方法getConnection抛出SQLException。此外，类DatabaseConnection可能应该是singleton，这意味着方法getConnection应该是静态方法。

类Register

我认为您应该使用PreparedStatement而不是Statement。
您还应该使用try-with-resources
我看不出这句台词的必要性：

e.getCause();

方法printStackTrace还将打印原因-如果有原因的话。
不要使用变量hasFirstName、hasLastName、hasAge和hasGrade，而是使用可以在方法initialize中设置的绑定，因为类Register是FXML控制器。这样，注册表单中的每个TextField都不需要一个 * Submit * 按钮。数据输入表单通常不需要单独提交每个字段。
与其显式设置每个Node的大小和位置，不如使用layouts。
关于顶部的Label，您可以使用单个Label，而不是每行文本都使用单独的Label。您可以插入line breaks，也可以居中对齐文本。
现在来看看你的问题，你需要在更新数据库之后"清除"注册表（而不是之前，就像你现在在代码中所做的那样）。
这是我的申请版本。
等级DatabaseConnection

package com.example.studentdatabase;

import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.SQLException;

public class DatabaseConnection {
    private static Connection databaseLink;

    public static Connection getConnection() throws SQLException {
        if (databaseLink == null) {
            String databaseName = "student_db";
            String databaseUser = "root";
            String databasePassword = "***";
            String url = "jdbc:mysql://localhost/" + databaseName;
            databaseLink = DriverManager.getConnection(url, databaseUser, databasePassword);
        }
        return databaseLink;
    }
}

等级Register
注意，它使用text blocks，也使用[JavaFX] alerts。

import javafx.event.ActionEvent;
import javafx.fxml.FXML;
import javafx.scene.control.Alert;
import javafx.scene.control.Alert.AlertType;
import javafx.scene.control.Button;
import javafx.scene.control.TextField;
import java.sql.Connection;
import java.sql.PreparedStatement;

public class Register {
    private int studentID = 0;

    @FXML
    private TextField gradeTF;

    @FXML
    private TextField ageTF;

    @FXML
    private TextField firstNameTF;

    @FXML
    private TextField lastNameTF;

    @FXML
    private Button registerButton;

    public void register(ActionEvent event) {
        String registerString = """
INSERT INTO student_data (student_id, first_name, last_name, age, grade)
VALUES (?, ?, ?, ?, ?)
                    """;
        try (Connection connection = DatabaseConnection.getConnection();
             PreparedStatement statement = connection.prepareStatement(registerString)) {
            statement.setInt(1, ++studentID);
            statement.setString(2, firstNameTF.getText());
            statement.setString(3, lastNameTF.getText());
            statement.setInt(4, Integer.valueOf(ageTF.getText()));
            statement.setInt(5, Integer.valueOf(gradeTF.getText()));
            statement.executeUpdate();
            Alert alert = new Alert(AlertType.INFORMATION);
            alert.setContentText("Registration Completed!");
            alert.setHeaderText(null);
            alert.showAndWait();
            firstNameTF.setText("");
            lastNameTF.setText("");
            ageTF.setText("");
            gradeTF.setText("");
            firstNameTF.setDisable(false);
            lastNameTF.setDisable(false);
            ageTF.setDisable(false);
            gradeTF.setDisable(false);
        }
        catch (Exception e) {
            e.printStackTrace();
        }
    }

    @FXML
    private void initialize() {
        registerButton.disableProperty().bind(firstNameTF.textProperty().isEmpty()
                                          .or(lastNameTF.textProperty().isEmpty())
                                          .or(ageTF.textProperty().isEmpty())
                                          .or(gradeTF.textProperty().isEmpty()));
    }
}

FXML文件

<?xml version="1.0" encoding="UTF-8"?>

<?import javafx.geometry.Insets?>
<?import javafx.scene.control.Button?>
<?import javafx.scene.control.Label?>
<?import javafx.scene.control.TextField?>
<?import javafx.scene.layout.BorderPane?>
<?import javafx.scene.layout.GridPane?>
<?import javafx.scene.text.Font?>

<BorderPane style="-fx-background-color: #f0db24;" xmlns:fx="http://javafx.com/fxml/1" fx:controller="com.example.studentdatabase.Register">
   <top>
      <Label text="Student Database&#xD;Sinhala Oratory &amp; Debating Society&#xD;D.S.Senanayake College - Col. 08&#xD;Registration Form">
         <font>
            <Font size="17.0" />
         </font>
         <textAlignment>CENTER</textAlignment>
      </Label>
      <BorderPane.margin>
          <Insets bottom="10.0" left="10.0" right="10.0" top="10.0"/>
      </BorderPane.margin>
   </top>
   <center>
      <GridPane hgap="10.0" vgap="10.0">
         <alignment>CENTER</alignment>
         <children>
            <Label text="First Name">
               <font>
                  <Font size="15.0" />
               </font>
               <GridPane.rowIndex>0</GridPane.rowIndex>
               <GridPane.columnIndex>0</GridPane.columnIndex>
            </Label>
            <TextField fx:id="firstNameTF">
                  <GridPane.rowIndex>0</GridPane.rowIndex>
                  <GridPane.columnIndex>1</GridPane.columnIndex>
            </TextField>
            <Label text="Last Name">
               <font>
                  <Font size="15.0" />
               </font>
               <GridPane.rowIndex>1</GridPane.rowIndex>
               <GridPane.columnIndex>0</GridPane.columnIndex>
            </Label>
            <TextField fx:id="lastNameTF">
                  <GridPane.rowIndex>1</GridPane.rowIndex>
                  <GridPane.columnIndex>1</GridPane.columnIndex>
            </TextField>
            <Label text="Age">
               <font>
                  <Font size="15.0" />
               </font>
               <GridPane.rowIndex>2</GridPane.rowIndex>
               <GridPane.columnIndex>0</GridPane.columnIndex>
            </Label>
            <TextField fx:id="ageTF">
                  <GridPane.rowIndex>2</GridPane.rowIndex>
                  <GridPane.columnIndex>1</GridPane.columnIndex>
            </TextField>
            <Label text="Grade">
               <font>
                  <Font size="15.0" />
               </font>
               <GridPane.rowIndex>3</GridPane.rowIndex>
               <GridPane.columnIndex>0</GridPane.columnIndex>
            </Label>
            <TextField fx:id="gradeTF">
                  <GridPane.rowIndex>3</GridPane.rowIndex>
                  <GridPane.columnIndex>1</GridPane.columnIndex>
            </TextField>
         </children>
      </GridPane>
      <BorderPane.margin>
          <Insets bottom="10.0" left="10.0" right="10.0" top="10.0"/>
      </BorderPane.margin>
   </center>
   <bottom>
      <Button fx:id="registerButton" mnemonicParsing="false" onAction="#register" text="Register" />
      <BorderPane.alignment>CENTER</BorderPane.alignment>
      <BorderPane.margin>
          <Insets bottom="10.0" left="10.0" right="10.0" top="10.0"/>
      </BorderPane.margin>
   </bottom>
</BorderPane>

类Main未更改，因此被省略。

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