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Why is “throws Exception” necessary when calling a function?
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In Java, as you may know, exceptions can be categorized into two: One that needs the throws clause or must be handled if you don't specify one and another one that doesn't. Now, see the following figure:
In Java, you can throw anything that ex...
“A project with an Output type of Class Library cannot be started directly”
...Single Startup Project
Select your Project in there and apply.
That's it. Now save and build your project. Run the project to see the output.
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get dictionary value by key
...n the dictionary.
return; // or whatever you want to do
}
// xmlfile is now equal to the value
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How to UPSERT (MERGE, INSERT … ON DUPLICATE UPDATE) in PostgreSQL?
...ou're on 9.5 and don't need to be backward-compatible you can stop reading now.
9.4 and older:
PostgreSQL doesn't have any built-in UPSERT (or MERGE) facility, and doing it efficiently in the face of concurrent use is very difficult.
This article discusses the problem in useful detail.
In general y...
How does a “stack overflow” occur and how do you prevent it?
...ite recursive call (given the usual amount of memory in standard computers nowadays).
When you make a call to a method, function or procedure the "standard" way or making the call consists on:
Pushing the return direction for the call into the stack(that's the next sentence after the call)
Usuall...
Difference between abstract class and interface in Python
...nd interface is a hairsplitting thing when you have duck typing. I don't know what "substantial" means. It's "real" -- it has substance -- from a design perspective. But from a language perspective there may be no support. You could adopt conventions to distinguish between an abstract class and ...
How can I search for a commit message on GitHub?
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Update (2017/01/05):
GitHub has published an update that allows you now to search within commit messages from within their UI. See blog post for more information.
I had the same question and contacted someone GitHub yesterday:
Since they switched their search engine to Elasticsearch it's ...
Why is React's concept of Virtual DOM said to be more performant than dirty model checking?
... might find in knockout or other MVVM style libraries. Essentially, React knows when to re-render the scene because it is able to observe when this data changes. Dirty checking is slower than observables because you must poll the data at a regular interval and check all of the values in the data str...
Force “git push” to overwrite remote files
...em up-to-date with the main development branch. Just let other developers know this will happen periodically so they'll know what to expect.
Update 2: Because of the increasing number of viewers I'd like to add some additional information on what to do when your upstream does experience a force pus...
What's the difference between an id and a class?
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Just confused these two things for quite a long time. Now I understood that "id" should be referred with unique element while "class" can be applied into multiple elements or things according their difference
– Michael Lai
Jul 20 '13 at 3:0...