I have two questions about Exceptions. Firstly, I got this message from my code… This error message means dividing by zero, such as by doing int a = 5 / 0; A method can throw an Exception class instance, can’t it? But this is an expression. Why can an expression throw an Exception class instance … Read more
This probably means that the field in the database is Null. You could add this line before the problematic line: In case that doesn’t work, you could also try changing the problematic line into this:
You’ll have to make this separate try blocks: This assumes you want to run code c only if code b failed. If you need to run code c regardless, you need to put the try blocks one after the other: I’m using except ExplicitException here because it is never a good practice to blindly ignore … Read more
Well, I’d expect it’s this line that’s throwing the exception: First() will throw an exception if it can’t find any matching elements. Given that you’re testing for null immediately afterwards, it sounds like you want FirstOrDefault(), which returns the default value for the element type (which is null for reference types) if no matching items are found: … Read more
As you are creating a database from scratch, you could use: Here is an identical scenario.
Here is the complete source code, updated from your source:
You should be able to create a custom exception class that extends the Exception class, for example: Usage:
java.lang.VerifyError can be the result when you have compiled against a different library than you are using at runtime. For example, this happened to me when trying to run a program that was compiled against Xerces 1, but Xerces 2 was found on the classpath. The required classes (in org.apache.* namespace) were found at runtime, so ClassNotFoundException was not the result. There … Read more
Use the MultiValueDict’s get method. This is also present on standard dicts and is a way to fetch a value while providing a default if it does not exist. Generally,
An Error “indicates serious problems that a reasonable application should not try to catch.” while An Exception “indicates conditions that a reasonable application might want to catch.” Error along with RuntimeException & their subclasses are unchecked exceptions. All other Exception classes are checked exceptions. Checked exceptions are generally those from which a program can recover & it might be a good idea … Read more