Any nontrivial app will have some level of the validation required. The POIApp app is somewhat trivial, but we have a small set of rules we need to enforce that will facilitate the discussion:
|
Property |
Rule |
|---|---|
|
|
This cannot be empty or null |
|
|
This contains a valid decimal number between |
|
|
This contains a valid decimal number between |
The EditText widget has a string property named Error, which simplifies the effort of displaying errors to the user, particularly if you want to be able to show all the fields with errors at once. The following screenshot displays the error received for leaving the Name field empty:
To use this facility, simply set the property to an error message and clear the property when no errors exist. The following example demonstrates implementing the rule for the Name property:
bool errors = false;
if (String.IsNullOrEmpty (_nameEditText.Text)) {
_nameEditText...