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applications:custom_errorhandling [2019/08/06 13:00] admin |
applications:custom_errorhandling [2020/07/08 13:14] (current) cduncan articles |
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| ~~NOTRANS~~ | ~~NOTRANS~~ | ||
| - | ~~Title: Custom error handling~~ | + | ~~Title: Custom Error Handling~~ |
| The application (ProjX) implements the **IExceptionListener** interface and registers itself as listener: | The application (ProjX) implements the **IExceptionListener** interface and registers itself as listener: | ||
| Line 13: | Line 13: | ||
| </file> | </file> | ||
| - | All Exceptions will be handled in one method: | + | All exceptions will be handled in the listener method: |
| <file java> | <file java> | ||
| Line 20: | Line 20: | ||
| </file> | </file> | ||
| - | So, it's very easy to change the default error handling. The default error handling shows a popup dialog with the error message and some details (stack trace). | + | So, it's very easy to change the default error handling which shows a popup dialog: |
| - | As example, we'll show the exceptions directly in the work-screens. So, every work-screen should be able to show error messages. To make this possible, we introduce the following interface: | + | {{:applications:error_dialog.png?nolink|}} |
| + | |||
| + | with the error message and some details (stack trace). \\ | ||
| + | \\ | ||
| + | As an example of a custom error handling, we'll show the exceptions directly in the workscreens. So, every workscreen should be able to show error messages. To make this possible, we introduce the following interface: | ||
| <file java> | <file java> | ||
| Line 30: | Line 34: | ||
| } | } | ||
| </file> | </file> | ||
| - | and all our work-screens should implement it like this example: | + | and all our workscreens should implement the interface, e.g.: |
| <file java> | <file java> | ||
| Line 41: | Line 45: | ||
| { | { | ||
| labelMain.setText("ErrorArea"); | labelMain.setText("ErrorArea"); | ||
| + | labelMain.setForeground(UIColor.red); | ||
| ... | ... | ||
| Line 62: | Line 67: | ||
| </file> | </file> | ||
| - | So, our work-screen example contains a new label in the SOUTH area (the bottom of the screen). The label will be hidden initially in **onLoad()**. Our screen is now ready to show error messages, but our application must be changed. To do this, we need a [[vaadin:customize_application|custom application]]. | + | So, our workscreen example contains a new label in the SOUTH area (the bottom of the screen). The label will be hidden initially in **onLoad()**. \\ |
| + | Our screen is now ready to show error messages, but our application must be changed. To do this, we need a [[vaadin:customize_application|custom application]]. | ||
| - | Our application contains following code: | + | Our application contains the following code: |
| <file java MyCustomApplication.java> | <file java MyCustomApplication.java> | ||
| Line 90: | Line 96: | ||
| public void showErrorMessage() | public void showErrorMessage() | ||
| { | { | ||
| - | String message = liErrors.get(0).getMessage(); | + | String message = ExceptionUtil.getRootCause(liErrors.get(0)).getMessage(); |
| | | ||
| for (IWorkScreen screen : getWorkScreens()) | for (IWorkScreen screen : getWorkScreens()) | ||
| Line 104: | Line 110: | ||
| } | } | ||
| </file> | </file> | ||
| - | We collect all occurred Exceptions and show one message at the end. We iterate through all opened work-screens and check if the interface is implemented. In our example, every work-screen has to implement the interface IErrorHandler. A better solution would be a custom work-screen base class, e.g. | + | We collect all occurred exceptions in a list - **liErrors** - and show one message at the end, see **showErrorMessages**. \\ |
| + | \\ | ||
| + | In **showErrorMessages**, we iterate through all opened workscreens and check if our interface is implemented. In our example, every workscreen has to implement the interface **IErrorHandler**. A better solution would be a custom workscreen base class, e.g. | ||
| <file java> | <file java> | ||
| Line 111: | Line 119: | ||
| } | } | ||
| </file> | </file> | ||
| - | and all our work-screens should extend this base screen: | + | and all our workscreens should extend this base screen: |
| <file java> | <file java> | ||
| public class FirstWorkScreen extends MyCustomWorkScreen | public class FirstWorkScreen extends MyCustomWorkScreen | ||
| </file> | </file> | ||
| + | |||
| + | And the result will look like the following: | ||
| + | |||
| + | {{:applications:error_screen.jpg?nolink|}} | ||