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我在寫這段代碼時遇到問題。該項目是一個密碼管理器應用程序，併爲這個當前衝刺我創建了一個Password模型和其他類持有Password的ArrayList一個叫做PasswordList。我在每個控制器類作爲private變量來創建一個PasswordList對象，並通過加載下一個場景的控制和設置PasswordList沿傳遞當前控制器的PasswordList（使同一列表在整個項目通過）。但是，創建一個新的Password對象時，將其添加到這個PasswordList，然後切換場景時，PasswordList是null。在場景之間傳遞參數的麻煩
所以，我有一個PasswordUI這是查看器，從那裏用戶可以點擊「添加」按鈕來查看CreatePasswordUI。我已經過測試，確保密碼已創建併成功添加到PasswordList，方法是將其打印到控制檯並使用調試器，然後檢查所有內容。我甚至可以返回添加另一個密碼，並且該列表仍然具有以前創建的所有對象Password。然而，在PasswordUI，將PasswordList還是來了作爲null即使我從以前的現場傳遞PasswordList。
我堅持，不知道該怎麼辦。
public class PasswordUIController implements Initializable {
private PasswordList passList;
/**
* Initializes the controller class.
*/
@FXML
TreeTableView passwordInfo;
@FXML
TreeTableColumn<String,String> acctColumn;
@FXML
Parent root;
@FXML
private void backButtonAction(ActionEvent event) throws Exception {
Stage stage = (Stage) root.getScene().getWindow();
FXMLLoader loader = new FXMLLoader(getClass().getResource("MainMenuUI.fxml"));
Pane mainMenuUI = (Pane)loader.load();
MainMenuController controller = loader.<MainMenuController>getController();
controller.setPassList(passList);
Scene scene = new Scene(mainMenuUI);
stage.setTitle("Main Menu");
stage.setScene(scene);
stage.show();
}
@FXML
private void addButtonAction(ActionEvent event) throws Exception {
Stage stage = (Stage) root.getScene().getWindow();
FXMLLoader loader = new FXMLLoader(getClass().getResource("CreatePasswordUI.fxml"));
Pane createPassUI = (Pane)loader.load();
CreatePasswordUIController controller = loader.<CreatePasswordUIController>getController();
controller.setPassList(passList);
Scene scene = new Scene(createPassUI);
stage.setTitle("Create Password");
stage.setScene(scene);
stage.show();
}
@Override
public void initialize(URL url, ResourceBundle rb) {
PasswordList pList = passList;
if (pList != null) {
ArrayList<Password> thePasswords = pList.getPasswordList();
TreeItem<String> passwords = new TreeItem<>("Passwords");
for (int i = 0; i < thePasswords.size(); i++) {
Password thePass = thePasswords.get(i);
//Creating tree items
TreeItem<String> username = new TreeItem<>("Username: " + thePass.getUsername());
TreeItem<String> password = new TreeItem<>("Password: " + thePass.getPassword());
TreeItem<String> comment = new TreeItem<>("Comment: " + thePass.getComment());
//Creating the root element
TreeItem<String> account = new TreeItem<>(thePass.getAccount());
account.setExpanded(true);
//Adding tree items to the root
account.getChildren().setAll(username, password, comment);
passwords.getChildren().add(account);
}
//Creating a column
acctColumn = new TreeTableColumn<>("Account");
//Defining cell content
acctColumn.setCellValueFactory(new Callback<TreeTableColumn.CellDataFeatures<String, String>, ObservableValue<String>>() {
@Override
public ObservableValue<String> call(TreeTableColumn.CellDataFeatures<String, String> param){
return new SimpleStringProperty(param.getValue().getValue());
}
});
//Creating a tree table view
passwordInfo = new TreeTableView<>();
passwordInfo.setRoot(passwords);
passwordInfo.getColumns().add(acctColumn);
} else {
}
}
/**
* @return the passList
*/
public PasswordList getPassList() {
return passList;
}
/**
* @param passList the passList to set
*/
public void setPassList(PasswordList passList) {
this.passList = passList;
}
}
public class CreatePasswordUIController implements Initializable {
private PasswordList passList;
/**
* Initializes the controller class.
*/
@FXML
Parent root;
@FXML
TextField accountTxt;
@FXML
TextField usernameTxt;
@FXML
TextField passwordTxt;
@FXML
TextField passwordTxt2;
@FXML
TextArea commentArea;
@FXML
TextField passwordGeneratorTxt;
@FXML
Label rating;
@FXML
Label matching;
@FXML
Label incorrect;
@FXML
private void backButtonAction(ActionEvent event) throws Exception {
Stage stage = (Stage) root.getScene().getWindow();
FXMLLoader loader = new FXMLLoader(getClass().getResource("MainMenuUI.fxml"));
Pane mainMenuUI = (Pane)loader.load();
MainMenuController controller = loader.<MainMenuController>getController();
controller.setPassList(passList);
Scene scene = new Scene(mainMenuUI);
stage.setTitle("Main Menu");
stage.setScene(scene);
stage.show();
}
@FXML
private void submitButtonAction(ActionEvent event) throws Exception {
String account = accountTxt.getText();
String username = usernameTxt.getText();
String password = passwordTxt.getText();
String password2 = passwordTxt2.getText();
String comment = commentArea.getText();
if (password.equals(password2) && username.length()>2) {
PasswordList pList = passList;
Password thePass = new Password(account, username, password, comment);
pList.addPassword(thePass);
Stage stage = (Stage) root.getScene().getWindow();
FXMLLoader loader = new FXMLLoader(getClass().getResource("PasswordUI.fxml"));
Pane passwordUI = (Pane)loader.load();
PasswordUIController controller = loader.<PasswordUIController>getController();
controller.setPassList(pList);
Scene scene = new Scene(passwordUI);
stage.setTitle("Password");
stage.setScene(scene);
stage.show();
} else {
incorrect.setVisible(true);
}
}
@FXML
private void generateButtonAction(ActionEvent event) {
PasswordGenerator passGen = new PasswordGenerator();
String password = passGen.generatePassword(true);
passwordGeneratorTxt.setText(password);
}
@Override
public void initialize(URL url, ResourceBundle rb) {
PasswordRater rater = new PasswordRater();
passwordTxt.textProperty().addListener(new ChangeListener() {
@Override
public void changed(ObservableValue observable, Object oldVal,Object newVal) {
String password = passwordTxt.getText();
rater.setPassword(password);
String ratingStr = rater.displayLevel();
rating.setText(ratingStr);
rating.setVisible(true);
if (passwordTxt.getText().equals(passwordTxt2.getText()) && !password.equals("")) {
matching.setText("Good!");
}
else
{
matching.setText("Passwords do not match.");
}
}
});
passwordTxt2.textProperty().addListener(new ChangeListener() {
@Override
public void changed(ObservableValue observable, Object oldVal,Object newVal) {
String password = passwordTxt.getText();
String password2 = passwordTxt2.getText();
if (password.equals(password2) && !password.equals("")) {
matching.setText("Good!");
} else {
matching.setText("Passwords do not match.");
}
matching.setVisible(true);
}
});
}
/**
* @return the passList
*/
public PasswordList getPassList() {
return passList;
}
/**
* @param passList the passList to set
*/
public void setPassList(PasswordList passList) {
this.passList = passList;
}
}