JavaFx ComboBox在第一次单击时未获得正确的值

我有一个来自JavaFXML的组合框，我用数组列表填充了它。当我第一次单击组合框时，它返回null，但当我再次单击它时，它将返回正确的值。真正应该发生的是，当我第一次单击组合框时，它应该在第一次单击而不是第二次单击时返回正确的值

我所拥有的：

package main.controller.manageAccounts;

import javafx.fxml.FXML;
import javafx.fxml.Initializable;
import javafx.scene.control.ComboBox;
import javafx.scene.control.TextField;
import javafx.scene.input.MouseEvent;
import main.model.MangeAccounts.ManageAccountsModel;

import java.net.URL;
import java.sql.SQLException;
import java.util.ResourceBundle;

public class ManageAccountsController implements Initializable {
    public ManageAccountsModel manageAccountsModel = new ManageAccountsModel();

    @FXML
    private ComboBox<String> customerDropDownList;
    @FXML
    private TextField txtUsername, txtFirstName, txtLastName, txtPassword, txtSecretQuestion, txtSecretQuestionAnswer;


    @Override
    public void initialize(URL location, ResourceBundle resources) {
        try {
            populateCustomerdropDownList();
        } catch (SQLException throwables) {
            throwables.printStackTrace();
        }

        if (manageAccountsModel.isDbConnected()) {
            System.out.println("Database connection established");
        } else {
            System.out.println("Database connection not established");
        }
    }

    public void populateCustomerdropDownList() throws SQLException {
        customerDropDownList.setItems(manageAccountsModel.getEmployeeId());
    }

    public void setFields(MouseEvent mouseEvent) throws SQLException {
        String getEmployeeId = customerDropDownList.getValue();
        int employeeId = Integer.parseInt(getEmployeeId);
        txtUsername.setText(manageAccountsModel.getUserName(employeeId));
        txtFirstName.setText(manageAccountsModel.getFirstName(employeeId));
        txtLastName.setText(manageAccountsModel.getLastName(employeeId));
        txtPassword.setText(manageAccountsModel.getPassword(employeeId));
        txtSecretQuestion.setText(manageAccountsModel.getSecretQuestion(employeeId));
        txtSecretQuestionAnswer.setText(manageAccountsModel.getSecretQuestionAnswer(employeeId));
        System.out.println(employeeId);
    }
}

FXML文件：

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

<?import javafx.scene.control.Button?>
<?import javafx.scene.control.ComboBox?>
<?import javafx.scene.control.TextField?>
<?import javafx.scene.layout.AnchorPane?>
<?import javafx.scene.layout.StackPane?>
<?import javafx.scene.text.Font?>
<?import javafx.scene.text.Text?>

<AnchorPane prefHeight="400.0" prefWidth="600.0" xmlns="http://javafx.com/javafx/16" xmlns:fx="http://javafx.com/fxml/1" fx:controller="main.controller.manageAccounts.ManageAccountsController">
   <children>
      <StackPane prefHeight="400.0" prefWidth="600.0">
         <children>
            <ComboBox fx:id="customerDropDownList" onMouseClicked="#setFields" prefWidth="150.0" translateY="80.0" StackPane.alignment="TOP_CENTER" />
            <Text strokeType="OUTSIDE" strokeWidth="0.0" text="Select Customer" translateY="60.0" StackPane.alignment="TOP_CENTER" />
            <TextField fx:id="txtUsername" maxHeight="-Infinity" maxWidth="-Infinity" minHeight="-Infinity" minWidth="-Infinity" prefHeight="30.0" prefWidth="200.0" text="Change Username" translateY="-60.0" />
            <TextField fx:id="txtFirstName" maxHeight="-Infinity" maxWidth="-Infinity" minHeight="-Infinity" minWidth="-Infinity" prefHeight="30.0" prefWidth="200.0" text="Change First Name" translateY="-25.0" />
            <TextField fx:id="txtLastName" maxHeight="-Infinity" maxWidth="-Infinity" minHeight="-Infinity" minWidth="-Infinity" prefHeight="30.0" prefWidth="200.0" text="Change Last Name" translateY="10.0" />
            <TextField fx:id="txtPassword" maxHeight="-Infinity" maxWidth="-Infinity" minHeight="-Infinity" minWidth="-Infinity" prefHeight="30.0" prefWidth="200.0" text="Change Password" translateY="45.0" />
            <TextField fx:id="txtSecretQuestion" maxHeight="-Infinity" maxWidth="-Infinity" minHeight="-Infinity" minWidth="-Infinity" prefHeight="30.0" prefWidth="200.0" text="Change Secret Question" translateY="80.0" />
            <TextField fx:id="txtSecretQuestionAnswer" maxHeight="-Infinity" maxWidth="-Infinity" minHeight="-Infinity" minWidth="-Infinity" prefHeight="30.0" prefWidth="200.0" text="Change Secret Answer Question" translateY="115.0" />
            <Button mnemonicParsing="false" text="Button" translateY="-30.0" StackPane.alignment="BOTTOM_CENTER" />
            <Text strokeType="OUTSIDE" strokeWidth="0.0" text="Manage User Accounts" translateY="20.0" StackPane.alignment="TOP_CENTER">
               <font>
                  <Font name="System Bold" size="20.0" />
               </font>
            </Text>
         </children>
      </StackPane>
   </children>
</AnchorPane>

正确的修复方法是，第一次单击将获得选中的值，而不是返回null，并且用户必须再次单击组合框：

将James提到的FXML文件
onMouseClicked=“#设置字段”
更改为
onAction=“#设置字段”
，并将
public void setFields（MouseEvent MouseEvent）
更改为
public void setFields（ActionEvent事件）

一旦用户单击下拉列表，就会立即获取值

更新代码

    public void setFields(ActionEvent event) throws SQLException {
        String getEmployeeId = customerDropDownList.getValue();
        int employeeId = Integer.parseInt(getEmployeeId);
        try {
            txtUsername.setText(manageAccountsModel.getUserName(employeeId));
            txtFirstName.setText(manageAccountsModel.getFirstName(employeeId));
            txtLastName.setText(manageAccountsModel.getLastName(employeeId));
            txtPassword.setText(manageAccountsModel.getPassword(employeeId));
            txtSecretQuestion.setText(manageAccountsModel.getSecretQuestion(employeeId));
            txtSecretQuestionAnswer.setText(manageAccountsModel.getSecretQuestionAnswer(employeeId));
            System.out.println(employeeId);
        } catch (SQLException e) {
            System.out.println("Work?");
        }
    }

使用
onAction
处理程序，而不是使用任何低级鼠标事件。（除此之外，如果用户使用键盘导航，您可能希望此功能能够正常工作。）如果不起作用，请创建并发布一个。基于单击，我们知道应该可以获得idies。“你试过我说的话了吗？”詹姆斯·丁说得对。正确的事件是组合框下拉项选择的操作。我猜您的第一个鼠标单击事件可能就是打开组合框弹出窗口的事件。另外，不清楚为什么要将事件传递给
setFields（）
，因为它不使用它。另外，我敢打赌你的
ManageAccountsModel
正在访问FXAT上的数据库，这也是一件坏事。此外，你最好在组合框的
值
属性上放置一个ChangeListener。
    public void setFields(ActionEvent event) throws SQLException {
        String getEmployeeId = customerDropDownList.getValue();
        int employeeId = Integer.parseInt(getEmployeeId);
        try {
            txtUsername.setText(manageAccountsModel.getUserName(employeeId));
            txtFirstName.setText(manageAccountsModel.getFirstName(employeeId));
            txtLastName.setText(manageAccountsModel.getLastName(employeeId));
            txtPassword.setText(manageAccountsModel.getPassword(employeeId));
            txtSecretQuestion.setText(manageAccountsModel.getSecretQuestion(employeeId));
            txtSecretQuestionAnswer.setText(manageAccountsModel.getSecretQuestionAnswer(employeeId));
            System.out.println(employeeId);
        } catch (SQLException e) {
            System.out.println("Work?");
        }
    }