无法从DialogPane，JavaFX的TextField输入中读取文本
无法从DialogPane，JavaFX的TextField输入中读取文本
提问于 2019-03-12 01:34:24
我正在尝试在JavaFX中创建一个简单的联系人应用程序。当我想创建新联系人时，它有一个带有TableView的主窗口和一个打开的DialogPane。在DialogPane中有几个TextFields，我想要从中收集文本，以便创建联系人列表。我的问题是，当我想要从DialogPane (来自TextFields)读取输入时，应用程序会运行一个错误(java.lang.NullPointerException)。当我在我的主窗口FXML文件中放入一个TextField时，我就可以很好地从textField访问这个文本了。当我想从DialogPane读取数据时，为什么我得到一个错误(错误-->文件: Controller.java，我注释了我得到一个错误的部分)？我被卡住了。有没有人能建议我哪里做错了？下面是我的代码：
Main.java
public class Main extends Application {
@Override
public void start(Stage primaryStage) throws Exception{
Parent root = FXMLLoader.load(getClass().getResource("mainwindow.fxml"));
primaryStage.setTitle("Your Contacts");
primaryStage.setScene(new Scene(root, 900, 600));
primaryStage.show();
}
public static void main(String[] args) {
launch(args);
}
}Controller.java
public class Controller {
@FXML
private BorderPane mainPanel;
public ObservableList<Contact> contactsList = FXCollections.observableArrayList();
@FXML
public void showAddContactDialog() {
Dialog<ButtonType> dialog = new Dialog<>();
dialog.initOwner(mainPanel.getScene().getWindow());
dialog.setTitle("Add new contact");
FXMLLoader fxmlLoader = new FXMLLoader();
fxmlLoader.setLocation(getClass().getResource("addContactDialog.fxml"));
try {
dialog.getDialogPane().setContent(fxmlLoader.load());
} catch (IOException e) {
Alert alert = new Alert(Alert.AlertType.ERROR);
alert.setTitle("Error");
alert.setHeaderText(null);
alert.setContentText("Couldn't load the dialog");
alert.showAndWait();
e.printStackTrace();
return;
}
dialog.getDialogPane().getButtonTypes().add(ButtonType.OK);
dialog.getDialogPane().getButtonTypes().add(ButtonType.CANCEL);
Optional<ButtonType> result = dialog.showAndWait();
if(result.isPresent() && result.get() == ButtonType.OK) {
//========================================================================================
//here is the error, I cannot read values from addContactDialog controller
ContactController contactController = new ContactController();
String firstName = contactController.getNewContact().getFirstName();
String lastName = contactController.getNewContact().getLastName();
String phoneNumber = contactController.getNewContact().getPhoneNumber();
String emailAddress = contactController.getNewContact().getEmailAddress();
Contact newContact = new Contact(firstName, lastName, phoneNumber, emailAddress);
contactsList.add(newContact);
//or alternatively
// Contact newContact = contactController.getNewContact();
// contactsList.add(newContact);
//========================================================================================
}
}
}ContactController.java
public class ContactController {
@FXML
private TextField firstNameField;
@FXML
private TextField lastNameField;
@FXML
private TextField phoneNumberFiled;
@FXML
private TextField emailField;
public Contact getNewContact() {
String firstName = firstNameField.getText();
String lastName = lastNameField.getText();
String phoneNumber = phoneNumberFiled.getText();
String emailAddress = emailField.getText();
Contact newContact = new Contact(firstName, lastName, phoneNumber, emailAddress);
return newContact;
}Contact.java
public class Contact {
private SimpleStringProperty firstName = new SimpleStringProperty("");
private SimpleStringProperty lastName = new SimpleStringProperty("");
private SimpleStringProperty phoneNumber = new SimpleStringProperty("");
private SimpleStringProperty emailAddress = new SimpleStringProperty("");
public Contact() {
}
public Contact(String firstName, String lastName, String phoneNumber, String emailAddress) {
this.firstName.set(firstName);
this.lastName.set(lastName);
this.phoneNumber.set(phoneNumber);
this.emailAddress.set(emailAddress);
}
public String getFirstName() {
return firstName.get();
}
public SimpleStringProperty firstNameProperty() {
return firstName;
}
public void setFirstName(String firstName) {
this.firstName.set(firstName);
}
public String getLastName() {
return lastName.get();
}
public SimpleStringProperty lastNameProperty() {
return lastName;
}
public void setLastName(String lastName) {
this.lastName.set(lastName);
}
public String getPhoneNumber() {
return phoneNumber.get();
}
public SimpleStringProperty phoneNumberProperty() {
return phoneNumber;
}
public void setPhoneNumber(String phoneNumber) {
this.phoneNumber.set(phoneNumber);
}
public String getEmailAddress() {
return emailAddress.get();
}
public SimpleStringProperty emailAddressProperty() {
return emailAddress;
}
public void setEmailAddress(String emailAddress) {
this.emailAddress.set(emailAddress);
}
@Override
public String toString() {
return "Contact{" +
"firstName=" + firstName +
", lastName=" + lastName +
", phoneNumber=" + phoneNumber +
", emailAddress=" + emailAddress +
'}';
}
}mainwindow.fxml
<BorderPane fx:id="mainPanel" fx:controller="sample.Controller"
xmlns:fx="http://javafx.com/fxml">
<top>
<MenuBar>
<menus>
<Menu text="Contacts">
<items>
<MenuItem text="Add new" onAction="#showAddContactDialog"/>
</items>
<items>
<MenuItem text="Edit" />
</items>
<items>
<MenuItem text="Delete"/>
</items>
<items>
<MenuItem text="Exit"/>
</items>
</Menu>
</menus>
<menus>
<Menu text="Info">
<items>
<MenuItem text="About"/>
</items>
</Menu>
</menus>
</MenuBar>
</top>
<center>
<TableView fx:id="contactsTable">
<columnResizePolicy>
<TableView fx:constant="CONSTRAINED_RESIZE_POLICY"/>
</columnResizePolicy>
<columns>
<TableColumn text="First Name">
<cellValueFactory>
<PropertyValueFactory property="firstName"/>
</cellValueFactory>
</TableColumn>
<TableColumn text="Last Name">
<cellValueFactory>
<PropertyValueFactory property="lastName"/>
</cellValueFactory>
</TableColumn>
<TableColumn text="Phone Number">
<cellValueFactory>
<PropertyValueFactory property="phoneNumber"/>
</cellValueFactory>
</TableColumn>
<TableColumn text="Email">
<cellValueFactory>
<PropertyValueFactory property="emailAddress"/>
</cellValueFactory>
</TableColumn>
</columns>
</TableView>
</center>
</BorderPane>addContactDialog.fxml
<DialogPane fx:controller="sample.ContactController" xmlns:fx="http://javafx.com/fxml">
<headerText>
Fill in the information for the new Contact
</headerText>
<content>
<GridPane vgap="10" hgap="10">
<Label text="First Name: " GridPane.rowIndex="0" GridPane.columnIndex="0"/>
<TextField fx:id="firstNameField" GridPane.rowIndex="0" GridPane.columnIndex="1"/>
<Label text="Last Name: " GridPane.rowIndex="1" GridPane.columnIndex="0"/>
<TextField fx:id="lastNameField" GridPane.rowIndex="1" GridPane.columnIndex="1"/>
<Label text="Phone Number: " GridPane.rowIndex="2" GridPane.columnIndex="0"/>
<TextField fx:id="phoneNumberField" GridPane.rowIndex="2" GridPane.columnIndex="1"/>
<Label text="Notes: " GridPane.rowIndex="3" GridPane.columnIndex="0"/>
<TextField fx:id="notesField" GridPane.rowIndex="3" GridPane.columnIndex="1"/>
</GridPane>
</content>
</DialogPane>回答 2
Stack Overflow用户
发布于 2019-03-12 04:42:34
好了，我发现了错误--我在ContactController.java文件中犯了一个打字错误。它应该有phoneNumberField而不是phoneNumberFiled字符串...
Stack Overflow用户
发布于 2019-03-12 02:03:19
你有没有试过这样放.toString String firstName = contactController.getNewContact().getFirstName().toString();
页面原文内容由Stack Overflow提供。腾讯云小微IT领域专用引擎提供翻译支持
原文链接：
https://stackoverflow.com/questions/55107416
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