Objekt wird aufgrund von Scope nicht initialisiert

Question

Entschuldigung für den langen Code, den ich hinzufügen werde. Ich versuche, bestimmte validierte Benutzereingabevariablen in einem Objekt zu speichern. Ich glaube, mein Problem liegt am Umfang der Variablen, deshalb habe ich den Fehler customerAccount may not have been initialized.

Wenn mir jemand in die richtige Richtung zeigen könnte, würde es sehr geschätzt werden.

import java.util.*; 
import java.io.*; 

public class ATM { 
    public void run() { 

     // USED FOR DEBUGGING PURPOSES. SET TO TRUE TO ENABLE DEBUGGING MODE 
     boolean debug = false, mainCheck = false, check = false; 
     Scanner input = new Scanner(System.in); 
     Scanner fInput = null; 
     int idNumber = 0; 
     String lastName, firstName, emailAddress, phoneNumber; 
     double startingBalance; 
     Client customerAccount; 

     File file = new File("accountData.txt"); 
     if(!file.exists()) { 
      System.out.println("File does not exist within directory. Creating file now."); 
      PrintWriter output = null; 
      try { 
       output = new PrintWriter(file); 
      } 
      catch(IOException e) { 
       System.out.println("Something went wrong during file creation."); 
      } 
      finally { 
       if (output != null) 
        output.close(); 
      } 
     } 

     ArrayList<Client> clientArr = new ArrayList<Client>(); 

     try { 
      fInput = new Scanner(new File("accountData.txt")); 
     } 
     catch(Exception e) { 
      System.out.println("ERROR: File Not Found."); 
      e.printStackTrace(); 
     } 
     while(fInput.hasNext()) { 
      try{ 
       int tempID = fInput.nextInt(); 
       String tempFName = fInput.next(); 
       String tempLName = fInput.next(); 
       String tempPNumber = fInput.next(); 
       String tempEmail = fInput.next(); 
       double tempBalance = fInput.nextFloat(); 
       Client tempClient = new Client(tempID, tempFName, tempLName, tempPNumber, tempEmail, tempBalance); 
       tempClient.getAccount().setID(tempID); 
       clientArr.add(tempClient); 

      if(debug == true) 
       System.out.println(tempID+" "+tempFName+" "+tempLName+" "+tempPNumber+" "+tempEmail+" $"+tempBalance); 
      } 
      catch(NoSuchElementException e) { 
       System.out.println("ERROR: Missing a required data field."); 
      } 
     } 

     if(debug == true) 
      System.out.println(clientArr.size()); 

     int menuChoice = 0; 
     while(menuChoice != 5) { 
      System.out.println("**********************************"); 
      System.out.println("Thank you for choosing Java World Bank!"); 
      System.out.println("Main Menu: "); 
      System.out.println("[1] Login as an existing user."); 
      System.out.println("[2] Display client list sorted by last name."); 
      System.out.println("[3] Display client list sorted by account number."); 
      System.out.println("[4] Create a new client."); 
      System.out.println("[5] Exit."); 
      System.out.println("===================================="); 
      do { 
       try { 
        System.out.println("Enter your choice: "); 
        menuChoice = input.nextInt(); 
        mainCheck = true; 
       } 
       // Checks if user enters an unexpected input (not a digit) 
       catch(InputMismatchException e) { 
        System.out.println("Invalid input! Please use a numeric value between 1 and 5."); 
        if(debug == true) 
         e.printStackTrace(); 
        input.nextLine(); 
       } 
      }while(!mainCheck); 

      switch(menuChoice) { 
       case 1: 
        System.out.println("Please enter your fist name: "); 
        input.nextLine(); 
        String loginFName = input.nextLine(); 
        while(loginFName.matches("[a-zA-Z]*") == false) { 
         System.out.println("Invalid input. First name needs to be all letters. Please try again."); 
         loginFName = input.nextLine(); 
        } 
        System.out.println("Please enter your last name: "); 
        String loginLName = input.nextLine(); 
        while(loginLName.matches("[a-zA-Z]*") == false) { 
         System.out.println("Invalid input. Last name needs to be all letters. Please try again."); 
         loginLName = input.nextLine(); 
        } 
        final String searchFName = loginFName; 
        final String searchLName = loginLName; 
        int loginValidation = 0; 

        Optional<Client> queryResult = clientArr.stream().filter(value -> value.getFName().equals(searchFName) 
                      &&value.getLName().equals(searchLName)).findFirst(); 
        if(queryResult.isPresent()) { 
         System.out.println("User "+loginFName+" "+loginLName+" successfully logged into. Welcome back to Java World Bank."); 
         menuChoice = 5; 
        } 
        else 
         System.out.println("Login failed. Returning to main menu."); 
        break; 
       case 2: 
        System.out.println("Clients of Java World Bank, sorted by last name: "); 
        clientArr.sort((p1, p2) -> p1.getLName().compareTo(p2.getLName())); 
        for(Client client : clientArr) 
         System.out.println(client); 
        menuChoice = 5; 
        break; 
       case 3: 
        System.out.println("Clients of Java World Bank, sorted by ID: "); 
        clientArr.sort((p1, p2) -> Integer.compare(p1.getAccount().getID(), 
                   p2.getAccount().getID())); 
        for(Client client : clientArr) 
         System.out.println(client); 
        menuChoice = 5; 
        break; 
       case 4: 
        System.out.println("You are now creating a new client account with Java World Bank!"); 
        System.out.println("Some information is required to create this account."); 
        System.out.println("What would you like your ID number to be? It must contain only integers."); 
        check = false; 
        do { 
         try { 
          System.out.println("Please enter your choice: "); 
          idNumber = input.nextInt(); 
          check = true; 
         } 
         catch(InputMismatchException e) { 
          System.out.println("ERROR: ID must contain integers only!"); 
          input.nextLine(); 
         } 
        }while(!check); 
        startingBalance = 0; 
        check = false; 
        // Continiously prompts user to enter valid input 
        do { 
         try { 
          System.out.println("What will be your starting balance?"); 
          startingBalance = input.nextDouble(); 
          check = true; 
         } 
         // Checks if user enters a value that is not a double 
         catch (InputMismatchException e) { 
          System.out.println("Invalid input! Please enter a numeric value."); 
          input.nextLine(); 
          if(debug == true) 
           e.printStackTrace(); 
         } 
        }while(!check); 
        customerAccount = new Client(idNumber, startingBalance); 
        System.out.println("Please enter client's first name: "); 
        firstName = input.nextLine(); 
        customerAccount.setFName(firstName); 
        // Verifies first name is only letters, either capital or lowercase 
        while(firstName.matches("[a-zA-Z]*") == false) { 
         System.out.println("Invalid input. First name needs to be all letters. Please try again."); 
         firstName = input.nextLine(); 
         customerAccount.setFName(firstName); 
        } 
        System.out.println("Please enter client's last name: "); 
        lastName = input.nextLine(); 
        customerAccount.setLName(lastName); 
        // Verifies last name is only letters, either capital or lowercase 
        while(lastName.matches("[a-zA-Z]*") == false) { 
         System.out.println("Invalid input. Last name needs to be all letters. Please try again."); 
         lastName = input.nextLine(); 
         customerAccount.setLName(lastName); 
        } 
        System.out.println("Please enter client's email address: "); 
        emailAddress = input.nextLine(); 
        customerAccount.setEmail(emailAddress); 
        // Verifies email address only uses lowercase/capital letters, dot, underscore, and/or dashes followed by @ symbol to specify domain 
        while(emailAddress.matches("^[A-Za-z0-9+_.-]+@(.+)$") == false) { 
         System.out.println("Invalid input. Email not in valid format. Please try again."); 
         emailAddress = input.nextLine(); 
         customerAccount.setEmail(emailAddress); 
        } 
        System.out.println("Please enter client's phone number: "); 
        phoneNumber = input.nextLine(); 
        // Verifies phone number follows valid North American format 000-000-0000 
        while(phoneNumber.matches("[0-9]\\d{2}-[0-9]\\d{2}-\\d{4}") == false) { 
         System.out.println("Invalid input. Phone number must be in the following format: 123-456-7890. Please try again."); 
         phoneNumber = input.nextLine(); 
         customerAccount.setPNumber(phoneNumber); 
        } 


      // Verifies that the starting balance the user inputs is positive 
      while(startingBalance < 0) { 
       System.out.println("**********************************"); 
       System.out.println("ERROR: You can not start with a negative balance."); 
       System.out.println("Please enter a POSITIVE value for your starting balance: "); 
       startingBalance = input.nextDouble(); 
      } 

     }//end switch 
    } 
     // Debugging to verify user input is correctly stored 
     if(debug == true) { 
      System.out.println(customerAccount.toString()); 
      Account testing = customerAccount.getAccount(); 
      System.out.println("ID: "+testing.getID()+ " Balance: "+testing.getBalance()); 
     } 

     System.out.println("********************************"); 
     System.out.println("Your account has been fully initialized! Thank you for choosing Java World Bank!"); 
     System.out.println("********************************"); 

     // Loops through menu prompt until user enters 4 to quit 
     int choice = 0; 
     while(choice != 4) { 
      System.out.println("Client Menu"); 
      System.out.println("[1] Check Balance"); 
      System.out.println("[2] Withdraw"); 
      System.out.println("[3] Deposit"); 
      System.out.println("[4] Exit"); 
      System.out.println("================================="); 

      // Continiously prompts user to enter valid input 
      check = false; 
      do { 
       try { 
        System.out.println("So... What do you want to do?"); 
        choice = input.nextInt(); 
        check = true; 
       } 
       // Checks if user enters an unexpected input (not a digit) 
       catch(InputMismatchException e) { 
        System.out.println("Invalid input! Please use a numeric value between 1 and 4."); 
        if(debug == true) 
         e.printStackTrace(); 
        input.nextLine(); 
       } 
      }while(!check); 

      double amount = 0; 
      switch(choice) { 
       // Will display updated balance 
       case 1: 
        System.out.println("Your current balance is: $"+customerAccount.getAccount().getBalance()); 
        System.out.println("********************************"); 
        break; 
       // Allows user to withdraw money from current balance 
       case 2: 
        // Continiously prompts user to enter valid input 
        check = false; 
        do { 
         try { 
          System.out.println("How much do you wish to withdraw?"); 
          amount = input.nextDouble(); 
          customerAccount.getAccount().withdraw(amount); // Passes withdraw value to Account class 
          System.out.println("********************************"); 
          check = true; 
         } 
         // Validates that customer has enough money to withdraw the specified amount 
         catch(OutOfMoney error) { 
          System.out.println("You do not have enough funds to do this."); 
          System.out.println("********************************"); 
         } 
         // Validates that customer enters expected input 
         catch(InputMismatchException e) { 
          System.out.println("INVALID INPUT. Please enter a numeric value."); 
          // Used to clear input buffer after catching exception 
          input.nextLine(); 
          System.out.println("********************************"); 
         } 
        }while(!check); 

        // Debugging to make sure values are correctly calculated 
        if(debug == true) 
         System.out.println(customerAccount.getAccount().getBalance()); 
        break; 
       // Allows user to deposit money to current balance 
       case 3: 
        check = false; 
        do { 
         try { 
          System.out.println("How much do you wish to deposit?"); 
          amount = input.nextDouble(); 
          customerAccount.getAccount().deposit(amount); // Passes deposit value to Account class 
          System.out.println("********************************"); 
          check = true; 
         } 
         // Validates that user enters expected input 
         catch(InputMismatchException e) { 
          System.out.println("Invalid input. Please enter a numeric value."); 
          // Used to clear input buffer after catching exception 
          input.nextLine(); 
          System.out.println("********************************"); 
         } 
        }while(!check); 

        // Debugging to make sure values are correctly calculated 
        if(debug == true) 
         System.out.println(customerAccount.getAccount().getBalance()); 
        break; 
       // Exits program 
       case 4: 
        System.out.println("Thank you for choosing Java World Bank!"); 
        break; 
       // Checks if user does not enter 1, 2, 3, or 4 in main menu prompt 
       default: 
        System.out.println("You have entered an invalid input. Please try again."); 
        System.out.println("********************************"); 
        break; 
      } 
     } 
     input.close(); 
    } 
} 

Answer 1

Da die Initialisierung des Objekts in einem Zustand passiert, kann der Compiler nicht herausfinden, wenn es initialisiert wird oder nicht, so müssen Sie sicherstellen, dass sein außerhalb einer Bedingung initialisiert, zum Beispiel es null machen.

Client customerAccount = null ; 

Answer 2

Erstens kann man hier über deklarieren und Initialisieren von Variablen sehen wollen: here

Sie initialisieren die customerAccount auf dieser Linie: customerAccount = new Client(idNumber, startingBalance);

jedoch, dass 4 innerhalb des Schalters für den Fall auftritt. Dann versuchen Sie in dieser Zeile System.out.println(customerAccount.toString()); auf die ToString-Funktion von CustomerAccount zuzugreifen. Da dieser Schritt nicht in Fall 4 ist, wird customerAccount möglicherweise nicht initialisiert.

Betrachten Sie den Fall, in dem die switch-Anweisung nicht auf 4 und debug auf true gesetzt ist. customerAccount wird aus dieser Zeile deklariert: Client customerAccount; Der Codepfad initialisiert ihn jedoch nicht, sodass Sie toString nicht aufrufen können.

Eine Lösung könnte sein, das customerAccount auf null zu initialisieren, wenn Sie es deklarieren oder auf new Client(), oder versuchen Sie nur, auf diese Variable zuzugreifen, nachdem es unbedingt initialisiert wurde. Ganz sicher ohne die Client-Klasse zu sehen. Beachten Sie, dass Sie im Null-Fall möglicherweise einige Null-Überprüfungen durchführen müssen. Wenn beispielsweise customerAccount null ist, wird customerAccount.toString() eine Ausnahme auslösen.