Creating custom class in java, using try-catch blocks, filewriter and printwriter

Question

Trying to surround this code with a try-catch block. However, upon many unsuccessful attempts i still cant get it to throw my CUSTOM exception message for when a user input a balance less than 0. Im trying to keep it extremely simple for learning purposes. I have my main throwing an IOException and InvalidException however i cant seem to figure out how to call the custom exception message. I removed it so the code looks more simple to viewers here. Any logic advice on how i should go about correcting this? ANY feedback is appreciated.

import java.util.Scanner;
import java.io.File;
import java.io.IOException;
import java.io.PrintWriter;

public class TestAccountWithException 
{

    public static void main(String[] args) throws IOException, InvalidBalanceException 
    {
        // variable declaration
        String fileName;
        String firstName;
        String lastName;
        double balance;
        int id = 1122;
        final double RATE = 4.50;

        Scanner input = new Scanner(System.in);
        System.out.print("Please enter file name: ");
        fileName = input.next();
        File fw = new File(fileName);

        // check if file already exists
        while(fw.exists()) 
        {
            System.out.print("File already exists, enter valid file name: ");
            fileName = input.next();
            fw = new File(fileName);
        }   


        System.out.print("Enter your first name: ");
        firstName = input.next();

        System.out.print("Enter your last name: ");
        lastName = input.next();

        // combine first and last name
        String fullName = firstName.concat(" " + lastName);

        System.out.print("Input beginnning balance: ");
        balance = input.nextDouble();   

        // pass object to printwriter and use pw to write to the file
        PrintWriter pw = new PrintWriter(fw);

        // print to created file
        pw.println(firstName);
        pw.println(lastName);
        pw.println(balance);
        pw.println(id);
        pw.println(RATE);

        AccountWithException acctException = new AccountWithException(fullName, balance, 1122, 4.50);
        System.out.println(acctException.toString());   
    } // end main
} // end class





    //  Account with exception class 

    public class AccountWithException {
      private int id;
      private double balance;
      private static double annualInterestRate;
      private java.util.Date dateCreated;
      // CRE additions for lab assignment
      private String name;

      // no-arg constructor to create default account
      public AccountWithException() {
        this.dateCreated = new java.util.Date();
      }

      // constructor for test account with exception that takes in arguments
      public AccountWithException(String newName, double newBalance, int newId, double newRate) {
          this.name = newName;
          this.balance = newBalance;
          this.id = newId; 
          AccountWithException.annualInterestRate = newRate;
          this.dateCreated = new java.util.Date();
      }

      // accessor methods
      public int getId() {
        return this.id;
      }

      public double getBalance() {
        return this.balance;
      }

      public static double getAnnualInterestRate() {
        return annualInterestRate;
      }

      public double getMonthlyInterest() {
        return this.balance * (this.annualInterestRate / 1200);
      }

      public java.util.Date getDateCreated() {
        return this.dateCreated;
      }

      public String getName() {
        return this.name;
      }

      // mutator methods
      public void setId(int newId) {
        this.id = newId;
      }

      public void setBalance(double newBalance) throws InvalidBalanceException {

          if(balance >= 0) {
            this.balance = newBalance;
          }
          else {
            throw new InvalidBalanceException(balance);
          }
      }   

      public static void setAnnualInterestRate(double newAnnualInterestRate) {
        annualInterestRate = newAnnualInterestRate;
      }

      public void setName(String newName) {
        this.name = newName;
      }

      // balance modification methods
      public void withdraw(double amount) {
        this.balance -= amount;
      }

      public void deposit(double amount) {
        this.balance += amount;
      }

      // override of Object method
      public String toString() {
        // return string with formatted data 
        // left-align 20 character column and right-align 15 character column
        return String.format("%-20s%15d\n%-20s%15tD\n%-20s%15s\n%-20s%15.2f%%\n%-20s%,15.2f\n",
          "ID:", this.id,
          "Created:", this.dateCreated,
          "Owner:", this.name,
          "Annual Rate:", this.annualInterestRate,
          "Balance:", this.balance);
      }
    }



public class InvalidBalanceException extends Exception {

    private double balance;

    public InvalidBalanceException(double balance) {
        // exceptions constructor can take a string as a message
        super("Invalid Balance " + balance);
        this.balance = balance;
    }

    public double getBalance() {
        return balance;
    }

}

score 1 · Answer 1 · answered Apr 03 '14 at 22:27

You are throwing your exception from the setBalance() method, but you aren't calling it in your constructor. You are just setting the value directly on the member variable.

Try this instead:

// constructor for test account with exception that takes in arguments
public AccountWithException(String newName, double newBalance, int newId, double newRate) throws InvalidBalanceException {
    setName(newName);
    setBalance(newBalance);
    setId(newId);
    setAnnualInterestRate(newRate);
    this.dateCreated = new java.util.Date();
}

Also, your setBalance method won't work, you are checking whether the existing balance is illegal, not the new value.

Try this instead:

public void setBalance(double newBalance) throws InvalidBalanceException {
    if (newBalance >= 0) {
        this.balance = newBalance;
    } else {
        throw new InvalidBalanceException(balance);
    }
}

Creating custom class in java, using try-catch blocks, filewriter and printwriter

1 Answers1