将参数从控制器传递到另一个控制器会产生java.lang.NullPointerException

时间:2018-06-09 10:03:22

标签: java mysql sql javafx fxml

我正在尝试获取某人用于登录的用户名,然后在有人制作apointment时将其插入数据库

这是“Programaritest”表格

ID_programare | Nume | Prenume | Data | Ora | Departament | Doctor | Username | Nr_telefon

这是帐户表,其中用户名保存为唯一

ID_account | Username | Password | Email | Nume |  Prenume | Admin

用户名的输入是通过文本字段从fxml获取的,在GetUsername方法中,我已在下面指出

package LicentaApp;



public class LogareController implements Initializable {
 public LoginVerifier loginVerifier = new LoginVerifier();





   @FXML
   private TextField Numeutilzator; Numeutilziator is the username that I am talking about

   @FXML
   private PasswordField Parola;

   @FXML
   private Label Stare;









 @Override
 public void initialize(URL location, ResourceBundle resources) {


  if (loginVerifier.Conexiune()) {
      Stare.setText("");
  } else {

      Stare.setText("Conexiune nereusita!");

  }

 }

 public void Autentificare (ActionEvent event) {
 try {
         if(loginVerifier.testaredate(Numeutilzator.getText(),     Parola.getText())) {
         Stare.setText("Autentificare reusita !");
         ((Node)event.getSource()).getScene().getWindow().hide();
            Stage StagePrincipala= new Stage();
            FXMLLoader incarcator= new FXMLLoader();
            Pane parinte = incarcator.load(getClass().getResource("/LicentaApp/Meniu.fxml").openStream());

            Scene scene = new Scene(parinte);
                scene.getStylesheets().add(getClass().getResource("Style1212.css").toExternalForm());
            StagePrincipala.setScene(scene);
            StagePrincipala.show();

          }
     else { 
         Stare.setText("Nume de utilizator sau parola incorect");

     }




} catch (SQLException e) {





     e.printStackTrace();
} catch (IOException e) {

    e.printStackTrace();
    }
 }
 @FXML
    public void Inregistrare(ActionEvent event) {
        try {
         ((Node)event.getSource()).getScene().getWindow().hide();
            Stage PS= new Stage();
            FXMLLoader incarcator= new FXMLLoader();
            Pane parinte = incarcator.load(getClass().getResource("/LicentaApp/InregistrareUser.fxml").openStream());
            Scene scena = new Scene(parinte);
            scena.getStylesheets().add(getClass().getResource("Style1212.css").toExternalForm());
            PS.setScene(scena);
            PS.show();
    } catch (Exception e) {

    }

*Here I m calling the function that I made in AddProgramareController and 
passing it the username located in Numeutilzator*

@FXML 
 public void GetUsername() {
     try {
     FXMLLoader loader=new     FXMLLoader(getClass().getResource("/LicentaApp/AddProgramare.fxml"));
     Parent root = (Parent) loader.load();

     AddProgramareController AddPr=loader.getController();
     AddPr.MyUsername(Numeutilzator.getText());


 } catch (IOException e) {
     e.printStackTrace();
 }
 }

}
}

这是将数据添加到数据库的类,我已经在下面的代码中指出了用户名的功能(我添加了所有代码,这样你就可以更好地理解上)

package LicentaApp;



public class AddProgramareController implements Initializable {
    ObservableList Timestamp=FXCollections.observableArrayList();




@FXML
private TextField Nume;

@FXML
private TextField Prenume;

@FXML
private TextField Ora;

@FXML
private DatePicker Data;

@FXML
private TextField Departament;

@FXML
private TextField Doctor;

@FXML
private TextField Nr_telefon;

@FXML
private TextField Numeutilizator;













public void initialize(URL location, ResourceBundle resources) {

} 

*This is the function that I'll call in GetUsername from LogareController
 public void MyUsername(String Numeutilizator) {
    this.Numeutilizator.setText(Numeutilizator);

}

@FXML 
private void AddProgramare(ActionEvent event) throws SQLException, IOException  {


    String Interogare1= "INSERT INTO programaritest(Nume,Prenume,Data,Ora,Departament,Doctor,Nr_telefon,Numeutilizator) VALUES(?,?,?,?,?,?,?,?)";

    String nume=Nume.getText();
    String prenume=Prenume.getText();

    LocalDate data=Data.getValue(); 

    String ora=Ora.getText();
    String departament=Departament.getText();
    String doctor=Doctor.getText();
    String nr_telefon=Nr_telefon.getText();
    String numeutilizator=Numeutilizator.getText();

    try {
        ConectaredB ConectaredB=new ConectaredB();
        Connection conexiune=ConectaredB.logareDB();
        PreparedStatement MG = conexiune.prepareStatement(Interogare1);


        MG.setString(1, nume);
        MG.setString(2, prenume);
        MG.setDate(3, Date.valueOf(data)); 
        MG.setString(4, ora);
        MG.setString(5, departament);
        MG.setString(6, doctor);
        MG.setString(7, nr_telefon);
        MG.setString(8, numeutilizator);

        MG.executeUpdate();

        // ...
   } catch (SQLException exceptie1) {
       exceptie1.printStackTrace(); 
   }


}
}

尝试添加新约会时我收到的错误消息是:

  

引起:java.lang.NullPointerException       在LicentaApp.AddProgramareController.AddProgramare(AddProgramareController.java:103)

     

第103行:String numeutilizator = Numeutilizator.getText();

所以来自numeutilizator的数据不是输入输出的数据,这意味着我无法将参数从控制器传递到另一个控制器。

P.S我跟着这个Passing Parameters JavaFX FXML,无法理解。

1 个答案:

答案 0 :(得分:0)

此异常可能有多种原因:

  • 控制器实例不与fxml
  • 一起使用
  • 与控件实例一起使用的fxml不包含fx:id="Numeutilizator"
  • 的元素

因此,我将发布一个简单的示例,该示例从使用fxml:

设计的场景中获取单个字符串

申请类

@Override
public void start(Stage primaryStage) {
    Button btn = new Button("Get input");
    btn.setOnAction((ActionEvent event) -> {
        FXMLLoader loader = new FXMLLoader(getClass().getResource("dialog.fxml"));
        Parent p;
        try {
            p = loader.load();
        } catch (IOException ex) {
            throw new RuntimeException(ex);
        }
        DialogController controller = loader.getController();

        Stage stage = new Stage(StageStyle.UTILITY);
        stage.initOwner(primaryStage);
        stage.setScene(new Scene(p, 100, 100));

        stage.showAndWait(); // display window and wait for close

        if (controller.isCanceled()) {
            System.out.println("canceled");
        } else {
            System.out.println("input submitted: " + controller.getText());
        }
    });

    StackPane root = new StackPane(btn);

    Scene scene = new Scene(root, 300, 300);

    primaryStage.setScene(scene);
    primaryStage.show();
}

dialog.fxml

<VBox xmlns:fx="http://javafx.com/fxml/1" fx:controller="fxml.DialogController">
    <children>
        <TextField fx:id="input"/>
        <Button text="submit" onAction="#submit"/>
        <Button text="cancel" onAction="#cancel"/>
    </children>
</VBox>

fxml.DialogController

public class DialogController {
    @FXML
    private TextField input;

    private boolean canceled = true;

    public boolean isCanceled() {
        return canceled;
    }

    public final String getText() {
        return input.getText();
    }

    private void close(boolean canceled) {
        this.canceled = canceled;
        input.getScene().getWindow().hide();
    }

    @FXML
    private void submit() {
        close(false);
    }

    @FXML
    private void cancel() {
        close(true);
    }

}

除了检索信息之外,您还可以在显示fxml的内容之前,将包含逻辑的对象传递给控制器​​,然后再显示fxml的内容。