Fixing the java.lang.NumberFormatException in Your Java Arithmetic Game

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Understanding the Problem

In the context of your game, the error is triggered when the user clicks on number buttons but later clears their input via a "Clear" button. For example, if a player enters the number 5, deletes it, and then attempts to enter 9, the application might still hold onto the previous number, interpreting it as the string 59 rather than just 9. The error occurs when the game tries to convert an invalid string (like an empty string) into an integer due to improper string handling.

Typical Causes of NumberFormatException

Attempting to parse an empty string as an integer.

Including characters in the string that cannot be converted to a number.

A Solution to the Problem

To fix the issue, you need to ensure that you are checking if the string is empty before attempting to parse it into a number. Below is a detailed breakdown of how to implement this into your existing code.

Step-by-Step Implementation

Check for Empty String Before Parsing: It’s essential to verify that the user's input (userAnswer) is not empty prior to parsing it. In the code snippet below, an additional check has been added to handle this.

[[See Video to Reveal this Text or Code Snippet]]

Output a Friendly Message: If userAnswer is empty, informing the player with a dialog box encourages correct input and improves user experience. In the modified example above, a clear message requests the user to provide an answer before sending their input.

Testing the Solution: After making these changes, test the application to ensure the problem is resolved. Enter various numeric inputs, clear them, and observe the application's behavior. Ensure that with each operation, the entries are properly parsed, and appropriate messages are displayed as needed.

Conclusion

Now that you’ve identified the root cause and implemented a solution, your Java arithmetic game should run smoothly without encountering parsing errors. Happy coding!