41 lines
1.7 KiB
Markdown
41 lines
1.7 KiB
Markdown
---
|
|
parent: Code Howtos
|
|
---
|
|
# Error Handling in JabRef
|
|
|
|
## Throwing and Catching Exceptions
|
|
|
|
Principles:
|
|
|
|
* All exceptions we throw should be or extend `JabRefException`; This is especially important if the message stored in the Exception should be shown to the user. `JabRefException` has already implemented the `getLocalizedMessage()` method which should be used for such cases (see details below!).
|
|
* Catch and wrap all API exceptions (such as `IOExceptions`) and rethrow them
|
|
* Example:
|
|
|
|
```java
|
|
try {
|
|
// ...
|
|
} catch (IOException ioe) {
|
|
throw new JabRefException("Something went wrong...",
|
|
Localization.lang("Something went wrong...", ioe);
|
|
}
|
|
```
|
|
|
|
* Never, ever throw and catch `Exception` or `Throwable`
|
|
* Errors should only be logged when they are finally caught (i.e., logged only once). See **Logging** for details.
|
|
* If the Exception message is intended to be shown to the User in the UI (see below) provide also a localizedMessage (see `JabRefException`).
|
|
|
|
_(Rationale and further reading:_ [https://www.baeldung.com/java-exceptions](https://www.baeldung.com/java-exceptions)_)_
|
|
|
|
## Outputting Errors in the UI
|
|
|
|
Principle: Error messages shown to the User should not contain technical details (e.g., underlying exceptions, or even stack traces). Instead, the message should be concise, understandable for non-programmers and localized. The technical reasons (and stack traces) for a failure should only be logged.
|
|
|
|
To show error message two different ways are usually used in JabRef:
|
|
|
|
* showing an error dialog
|
|
* updating the status bar at the bottom of the main window
|
|
|
|
```text
|
|
TODO: Usage of status bar and `DialogService`
|
|
```
|