I'm trying to make an application that takes a username and password to store into a text document. However, I can't seem to get the application to create the file on the first run, it only seems to work if I manually create the file. I've tried changing up when I make the file in the DataCenter, but I keep getting the same error:
Caused by: java.io.FileNotFoundException: file.txt (The system cannot find the file specified)
at java.base/java.io.FileInputStream.open0(Native Method)
at java.base/java.io.FileInputStream.open(FileInputStream.java:216)
at java.base/java.io.FileInputStream.<init>(FileInputStream.java:157)
at java.base/java.util.Scanner.<init>(Scanner.java:641)
at Q02.start(Q02.java:31)
public class DataCenter {
private static String filename = "file.txt";
private File file;
private static DataCenter instance = null;
private DataCenter() {
if (instance != null) {
throw new Error();
}
file = new File(filename);
}
public static DataCenter getInstance() {
if (instance == null) {
instance = new DataCenter();
}
return instance;
}
public File getFile() {
return file;
}
}
public class UserData {
private String username;
private String password;
public UserData() {
}
public UserData(String username, String password) {
this.username = username;
this.password = password;
}
public void setUsername(String username) {
this.username = username;
}
public void setPassword(String password) {
this.password = password;
}
public String getUsername() {
return this.username;
}
public String getPassword() {
return this.password;
}
public String toString() {
return "Username: " this.username " Password: " this.password;
}
public boolean equals(UserData object) {
boolean equals = true;
if(!(this.username.equals(object.username)))
equals = false;
return equals;
}
}
import java.io.FileWriter;
import java.io.PrintWriter;
import java.util.ArrayList;
import java.util.Scanner;
import javafx.application.Application;
import javafx.event.EventHandler;
import javafx.geometry.Insets;
import javafx.geometry.Pos;
import javafx.scene.Scene;
import javafx.scene.control.Alert;
import javafx.scene.control.Alert.AlertType;
import javafx.scene.control.Button;
import javafx.scene.control.Label;
import javafx.scene.control.TextField;
import javafx.scene.input.KeyEvent;
import javafx.scene.layout.GridPane;
import javafx.scene.layout.HBox;
import javafx.scene.layout.VBox;
import javafx.stage.Stage;
public class Q02 extends Application {
@Override
public void start(Stage stage) throws Exception {
DataCenter center1 = DataCenter.getInstance();
Alert a = new Alert(AlertType.NONE);
int userIndex = 0;
int passIndex = 1;
ArrayList<UserData> users = new ArrayList<>();
ArrayList<String> userData = new ArrayList<>();
Scanner sc = new Scanner(center1.getFile());
while(sc.hasNext()) {
userData.add(sc.next());
}
for(int i = 0; i < userData.size()/2; i ) {
users.add(new UserData(userData.get(userIndex),userData.get(passIndex)));
userIndex = userIndex 2;
passIndex = passIndex 2;
}
VBox vbox = new VBox();
VBox vbox1 = new VBox();
HBox hbox = new HBox();
GridPane root = new GridPane();
TextField tfUser = new TextField();
TextField tfPass = new TextField();
TextField tfConfirm = new TextField();
Label username = new Label("Username");
Label password = new Label("Password");
Label confirm = new Label("Confirm Password");
vbox.getChildren().addAll(tfUser,tfPass,tfConfirm);
vbox1.getChildren().addAll(username, password, confirm);
Button btnSignUp = new Button("Sign Up");
btnSignUp.setDisable(true);
btnSignUp.setOnAction(e -> {
boolean userExists = false;
UserData user = new UserData(tfUser.getText(),tfPass.getText());
for(int i = 0; i < users.size(); i ) {
if(user.getUsername().equals(users.get(i).getUsername())) {
a.setAlertType(AlertType.CONFIRMATION);
a.setContentText("Registration Failed!");
a.show();
userExists = true;
}
}
//System.out.println(user);
if(userExists == false) {
try {
PrintWriter pw = new PrintWriter(new FileWriter(center1.getFile(),true));
pw.append(tfUser.getText() " ");
pw.append(tfPass.getText() " ");
users.add(user);
a.setAlertType(AlertType.CONFIRMATION);
a.setContentText("Registration Complete!");
a.show();
pw.close();
} catch(Exception ex) {
ex.printStackTrace();
}
}
});
tfPass.setOnKeyTyped(new EventHandler<KeyEvent>() {
public void handle(KeyEvent e) {
String username = tfUser.getText();
String password = tfPass.getText();
String confirm = tfConfirm.getText();
btnSignUp.setDisable(!validateUserLogin(username,password,confirm));
}
});
tfUser.setOnKeyTyped(new EventHandler<KeyEvent>() {
public void handle(KeyEvent e) {
String username = tfUser.getText();
String password = tfPass.getText();
String confirm = tfConfirm.getText();
btnSignUp.setDisable(!validateUserLogin(username,password,confirm));
}
});
tfConfirm.setOnKeyTyped(new EventHandler<KeyEvent>() {
public void handle(KeyEvent e) {
String username = tfUser.getText();
String password = tfPass.getText();
String confirm = tfConfirm.getText();
btnSignUp.setDisable(!validateUserLogin(username,password,confirm));
}
});
Button btnCancel = new Button("Cancel");
btnCancel.setOnAction(e -> {
tfUser.setText("");
tfPass.setText("");
tfConfirm.setText("");
});
hbox.getChildren().addAll(btnSignUp, btnCancel);
hbox.setSpacing(8);
root.add(vbox, 1, 0);
root.add(vbox1, 0, 0);
root.add(hbox, 1, 3);
hbox.setPadding(new Insets(8));
vbox.setSpacing(8);
vbox1.setSpacing(16);
root.setAlignment(Pos.CENTER);
vbox.setAlignment(Pos.CENTER);
vbox1.setAlignment(Pos.CENTER_RIGHT);
vbox1.setPadding(new Insets(5));
Scene login = new Scene(root,400,400);
stage.setScene(login);
stage.show();
}
public static void main(String args[]) {
Application.launch();
}
private boolean validateUserLogin(String username, String password, String confirmation) {
boolean login = true;
if(!(username.length() >= 6 && password.length() >= 6)) {
login = false;
}
if(!(password.equals(confirmation))) {
login = false;
}
return login;
}
}
CodePudding user response：
Check if the file exists in the first line of your main method and if don't exist create it :
public static void main(String args[]) throws IOException {
if (Files.notExists(Path.of("YOUE-FILE_PATH"))) {
Files.createDirectories(Path.of("PARENT-FOLDER"));
Files.createFile(Path.of("YOUE-FILE_PATH"))
}
Application.launch();
}
And if you use older java 11 you can use Paths.get instead Path.of You need also to check if the parent folder does not exist.
CodePudding user response：
Check if the file exists in the constructor itself. Update the private constructor of DataCenter like below.
private DataCenter() {
if (instance != null) {
throw new Error();
}
// create the file if it doesn't exist already.
if(!Files.exists(Path.of(filename)){
Files.createDirectories(Path.of("<PARENT-FOLDER"));
Files.createFile(Path.of(filename))
}
file = new File(filename);
}