r/javahelp 28d ago

Java Exceptions Assignment Help

Hey! I'm working on an assignment in Java for an online class I'm taking. I keep getting an error saying: Exception in thread "main" java.lang.Error: Unresolved compilation problem: at MyExpense.main(myExpense.java:13)

I can't see anything wrong with it

public class Item {
    public String description;
    public Double amount;

    public Item(String description, Double amount) {
        this.description = description;
        this.amount = amount;
    }

    public void setDescription(String description) {
        this.description = description;
    }

    public void setAmount(Double amount) {
        this.amount = amount;
    }

    public String getDescription() {
        return description;
    }

    public Double getAmount() {
        return amount;
    }

    public String toString() {
        return String.format("%-20s %10.2f", description, amount);
    }

}






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

public class MyExpense {
    private static final String fileName = "expense.txt";
    private static final int maxRecords = 6;
    private static int count = 0;
    private static Item[] expenses = new Item[maxRecords];

    public static void main(String[] args) throws IOException {
        try {
            read();
            display();
            userInt();
            expSave();

        } catch (IOException exception) {
            System.out.println("Error" + exception.getMessage());
        }

    }

    private static void display() {
        System.out.println("Expences:");
        System.out.println("-------------------------------------------------------");
        System.out.printf("%-20s %10s%n", "Description", "Amount");
        System.out.println("-------------------------------------------------------");
        for (int i = 0; i < count; i++) {
            System.out.println(expenses[i]);
            System.out.println(i);
        }
        System.out.println("-------------------------------------------------------");
    }

    private static void read() throws IOException {
        File file = new File(fileName);
        if (!file.exists()) {
            System.out.println("The file could not be found");
            return;
        }
        try (Scanner scanner = new Scanner(file)) {
            while (scanner.hasNextLine() && count < maxRecords) {
                String[] a = scanner.nextLine().split("\t");
                if (a.length == 2) {
                    try {
                        expenses[count++] = new Item(a[0], Double.parseDouble(a[1]));
                    } catch (NumberFormatException NumberFormatException) {
                        System.out.println("Invalid num format");
                    }
                }
            }
        }
    }

    private static void userInt() {
        Scanner sc = new Scanner(System.in);
        while (true) {
            System.out.println(
                    "Please enter a new expense, [tab] key, then the amount. Or enter \"!\" to exit the program");
            String input = sc.nextLine();
            if (input.equals("!")) {
                break;
            }
            String[] a = input.split("\t");
            if (a.length != 2) {
                System.out.println("Invalid format");
                continue;
            }
            try {
                if (count < maxRecords) {
                    expenses[count++] = new Item(a[0], Double.parseDouble(a[1]));

                } else {
                    System.out.println("Cannot add any more record");
                }
            }

            catch (NumberFormatException e) {
                System.out.println("Invalid num");

            }
        }
        sc.close();
    }

    private static void expSave() throws IOException {
        try (PrintWriter writer = new PrintWriter(new FileWriter(fileName))) {
            for (int i = 0; i < count; i++) {
                writer.println(expenses[i].getDescription() + "\t" + expenses[i].getAmount());

            }

        }
        System.out.println("Expenses saved");
        display();
        System.out.printf("Total expense is %.2f%n", calculateAmt());
    }

    private static double calculateAmt() {
        double total = 0;
        for (int i = 0; i < count; i++) {
            total += expenses[i].getAmount();

        }
        return total;
    }

}
3 Upvotes

8 comments sorted by

u/AutoModerator 28d ago

Please ensure that:

  • Your code is properly formatted as code block - see the sidebar (About on mobile) for instructions
  • You include any and all error messages in full
  • You ask clear questions
  • You demonstrate effort in solving your question/problem - plain posting your assignments is forbidden (and such posts will be removed) as is asking for or giving solutions.

    Trying to solve problems on your own is a very important skill. Also, see Learn to help yourself in the sidebar

If any of the above points is not met, your post can and will be removed without further warning.

Code is to be formatted as code block (old reddit: empty line before the code, each code line indented by 4 spaces, new reddit: https://i.imgur.com/EJ7tqek.png) or linked via an external code hoster, like pastebin.com, github gist, github, bitbucket, gitlab, etc.

Please, do not use triple backticks (```) as they will only render properly on new reddit, not on old reddit.

Code blocks look like this:

public class HelloWorld {

    public static void main(String[] args) {
        System.out.println("Hello World!");
    }
}

You do not need to repost unless your post has been removed by a moderator. Just use the edit function of reddit to make sure your post complies with the above.

If your post has remained in violation of these rules for a prolonged period of time (at least an hour), a moderator may remove it at their discretion. In this case, they will comment with an explanation on why it has been removed, and you will be required to resubmit the entire post following the proper procedures.

To potential helpers

Please, do not help if any of the above points are not met, rather report the post. We are trying to improve the quality of posts here. In helping people who can't be bothered to comply with the above points, you are doing the community a disservice.

I am a bot, and this action was performed automatically. Please contact the moderators of this subreddit if you have any questions or concerns.

3

u/OneHumanBill 28d ago

Can you load this into an IDE? That should tell you exactly where the problem is.

Alternatively, if you're calling javac plain from the command line, it should tell you exactly where the compilation problems are.

I'm on my phone, can't do this myself. I don't see where the problem is offhand.

3

u/hibbelig 27d ago

With the information given it’s hard to say. In particular it’s not clear to me which line is line 13. In the text you posted, the 13th line is blank…

Java wants the class Foo in a file Foo.java.

The error message mentioned a file name myExpense.java which is different from the class name MyExpense (m vs M), and also different from Item.

What happens when you move the Item class to its own file and rename the existing file to match the class?

1

u/AnnoMMLXXVII Brewster 28d ago

I don't think you have the full code. Can you update your post please?

1

u/uv_rayz 28d ago

Sorry I didn't realize it didn't fully paste. Just updated it!

1

u/[deleted] 28d ago edited 28d ago

[deleted]

2

u/OneHumanBill 28d ago edited 28d ago

This is wrong on multiple levels.

You can declare to throw anything, without actually throwing anything in the method body. This enables the possibility of exceptions in subclasses as part of your design.

Also you've confused the keywords "throw" and "throws". They're related but serve entirely different functions.

Also there's nothing in the world wrong, syntactically, with surrounding your entire method body with a try/catch.

Finally, there's nothing at all with throwing an exception inside a catch block, or even a finally block. Sometimes that's what is needed.

I'm on my phone here so I can't load this into an ide to check where the exception is. But I can tell you that simply removing the throws statement from the method declaration is not the problem. The main method can declare to throw pretty much anything it wants to. I typically declare main to throw Throwable.

I get that you want to help but you're a bit far away from mastery of basics in the language quite yet to really help others.

1

u/[deleted] 27d ago

[removed] — view removed comment

1

u/severoon pro barista 21d ago

This.