JavaFX中的NullPointerException在TableView中初始化 [英] NullPointerException in JavaFX initialize in TableView
问题描述
我有这个控制器类用于在TableView中显示数据库查询,但是我的错误是NullPointerException,带有setCellValueFactory(new PropertyValueFactory
I have this controller class for showing a database query in a TableView, but i am having error of NullPointerException with the "setCellValueFactory(new PropertyValueFactory"
package aplicativo;
import java.net.URL;
import java.util.ResourceBundle;
import javafx.collections.FXCollections;
import javafx.collections.ObservableList;
import javafx.fxml.FXML;
import javafx.fxml.Initializable;
import javafx.scene.control.Button;
import javafx.scene.control.TableColumn;
import javafx.scene.control.TableView;
import javafx.scene.control.TextField;
import javafx.scene.control.cell.PropertyValueFactory;
public class Controle implements Initializable{
@FXML
private TextField txtCampo,txtCampo2;
@FXML
private Button btAdicionar,btConsultar;
@FXML
private TableView<Pessoa> tabValues;
@FXML
private TableColumn<Pessoa, Integer> tbcCod;
private TableColumn<Pessoa, String>tbcNome;
ObservableList<Pessoa> List = FXCollections.observableArrayList();
@FXML
private void btAdd(){
insertBD a = new insertBD(txtCampo.getText());
consultaBD b = new consultaBD();
List = b.consultaTudo();
tabValues.setItems(List);
txtCampo.clear();
}
@FXML
private void btCons(){
String tx = txtCampo2.getText();
if(tx.isEmpty()){
}else{
consultaBD a = new consultaBD();
a.consultaParecido(tx, "nome");
txtCampo2.clear();
}
}
@Override
public void initialize(URL arg0, ResourceBundle arg1) {
// TODO Auto-generated method stub
tbcCod.setCellValueFactory(new PropertyValueFactory<Pessoa, Integer>("cod"));
tbcNome.setCellValueFactory(new PropertyValueFactory<Pessoa, String>("nome"));
tabValues.setItems(List);
tabValues.getColumns().addAll(tbcCod,tbcNome);
}
}
NullPointerExcepetion:
The NullPointerExcepetion:
Exception in Application start method
java.lang.reflect.InvocationTargetException
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)
at java.lang.reflect.Method.invoke(Unknown Source)
at com.sun.javafx.application.LauncherImpl.launchApplicationWithArgs(Unknown Source)
at com.sun.javafx.application.LauncherImpl.launchApplication(Unknown Source)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)
at java.lang.reflect.Method.invoke(Unknown Source)
at sun.launcher.LauncherHelper$FXHelper.main(Unknown Source)
Caused by: java.lang.RuntimeException: Exception in Application start method
at com.sun.javafx.application.LauncherImpl.launchApplication1(Unknown Source)
at com.sun.javafx.application.LauncherImpl.lambda$launchApplication$152(Unknown Source)
at com.sun.javafx.application.LauncherImpl$$Lambda$50/1645995473.run(Unknown Source)
at java.lang.Thread.run(Unknown Source)
Caused by: javafx.fxml.LoadException:
/C:/Users/lucas/workspace/BDFX/bin/aplicativo/Tela.fxml
at javafx.fxml.FXMLLoader.constructLoadException(Unknown Source)
at javafx.fxml.FXMLLoader.loadImpl(Unknown Source)
at javafx.fxml.FXMLLoader.loadImpl(Unknown Source)
at javafx.fxml.FXMLLoader.loadImpl(Unknown Source)
at javafx.fxml.FXMLLoader.loadImpl(Unknown Source)
at javafx.fxml.FXMLLoader.loadImpl(Unknown Source)
at javafx.fxml.FXMLLoader.loadImpl(Unknown Source)
at javafx.fxml.FXMLLoader.loadImpl(Unknown Source)
at javafx.fxml.FXMLLoader.load(Unknown Source)
at aplicativo.Main.start(Main.java:13)
at com.sun.javafx.application.LauncherImpl.lambda$launchApplication1$159(Unknown Source)
at com.sun.javafx.application.LauncherImpl$$Lambda$53/1031257736.run(Unknown Source)
at com.sun.javafx.application.PlatformImpl.lambda$runAndWait$172(Unknown Source)
at com.sun.javafx.application.PlatformImpl$$Lambda$45/186276003.run(Unknown Source)
at com.sun.javafx.application.PlatformImpl.lambda$null$170(Unknown Source)
at com.sun.javafx.application.PlatformImpl$$Lambda$48/1529876784.run(Unknown Source)
at java.security.AccessController.doPrivileged(Native Method)
at com.sun.javafx.application.PlatformImpl.lambda$runLater$171(Unknown Source)
at com.sun.javafx.application.PlatformImpl$$Lambda$47/237061348.run(Unknown Source)
at com.sun.glass.ui.InvokeLaterDispatcher$Future.run(Unknown Source)
at com.sun.glass.ui.win.WinApplication._runLoop(Native Method)
at com.sun.glass.ui.win.WinApplication.lambda$null$145(Unknown Source)
at com.sun.glass.ui.win.WinApplication$$Lambda$36/2117255219.run(Unknown Source)
... 1 more
Caused by: java.lang.NullPointerException
at aplicativo.Controle.initialize(Controle.java:52)
... 23 more
Exception running application aplicativo.Main
任何解决方案?
推荐答案
控制器中的一个实例字段是缺少 @FXML
注释。由于该字段是私有的,因此FXML加载程序无法在加载期间将控制引用注入字段。以下是您的实例字段声明:
One of the instance fields in your controller is lacking an @FXML
annotation. Since the field is private, the FXML loader is unable to inject the control reference into the field during loading. Here are your instance field declarations:
@FXML
private TextField txtCampo,txtCampo2;
@FXML
private Button btAdicionar,btConsultar;
@FXML
private TableView<Pessoa> tabValues;
@FXML
private TableColumn<Pessoa, Integer> tbcCod;
private TableColumn<Pessoa, String>tbcNome;
请注意,最后一个字段tbcNome未注释。因此,当调用initialize方法时, tbcNome
字段包含 null
引用,从而导致异常。
Notice that the last field, tbcNome, is not annotated. As a result, when your initialize method is called, the tbcNome
field contains a null
reference, resulting in the exception.
要解决您的问题,您可能需要做的就是将 @FXML
注释添加到实例字段声明中对于 tbcNome
。
To fix your problem, all you may need to do is add the @FXML
annotation to the instance field declaration for tbcNome
.
您可能通过在您的类型中列出多个变量的习惯来鼓励此错误声明,例如。 private Button btAdicionar,btConsultar;
。在我看来,这是一个坏习惯,可以鼓励这样的错误发生。我建议您尝试采用编码样式,其中每个实例字段都有自己的类型声明语句。
You may have encouraged this error by adopting the habit of listing more than one variable in your type declarations, eg. private Button btAdicionar, btConsultar;
. In my opinion, this is a bad habit that can encourage errors like this to happen. I would suggest that you try to adopt the coding style in which each instance field has its own type declaration statement.
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