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What does “Object reference not set to an instance of an object” mean? [duplicate]

...hod() { } } This is a very common error and can occur because of all kinds of reasons. The root cause really depends on the specific scenario that you've encountered. If you are using an API or invoking methods that may return null then it's important to handle this gracefully. The main m...
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Intermittent log4net RollingFileAppender locked file issue

... Try adding <lockingModel type="log4net.Appender.FileAppender+MinimalLock" /> to your <appender /> element. There is some performance impact because this means that log4net will lock the file, write to it, and unlock it for each write operation (as opposed to the default behavior,...
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Why would I use a templating engine? jsp include and jstl vs tiles, freemarker, velocity, sitemesh

...scope, by controllers) to fill these placeholders. Yes, references are really the core of VTL: <b>Hello $username!</b> or #if($listFromModel.size() > 1) You have many entries! #end Efficiency - <%@ include file="file.jsp" %> is more efficient than anything else, b...
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What is the difference between atan and atan2 in C++?

... std::atan2 allows calculating the arctangent of all four quadrants. std::atan only allows calculating from quadrants 1 and 4. share | ...
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Google MAP API Uncaught TypeError: Cannot read property 'offsetWidth' of null

... This problem is usually due to the map div not being rendered before the javascript runs that needs to access it. You should put your initialization code inside an onload function or at the bottom of your HTML file, just before the tag, so th...
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How to fully clean bin and obj folders within Visual Studio?

... As others have responded already Clean will remove all artifacts that are generated by the build. But it will leave behind everything else. If you have some customizations in your MSBuild project this could spell trouble and leave behind stuff you would think it should have...
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How to print the full traceback without halting the program?

...rmed XML, missing entries, and other things I've yet to categorize. I initially made this program to handle errors like this: ...
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Pythonic way to check if a file exists? [duplicate]

... It seems to me that all other answers here (so far) fail to address the race-condition that occurs with their proposed solutions. Any code where you first check for the files existence, and then, a few lines later in your program, you create it...
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Unable to execute dex: Multiple dex files define

...der and not in your source folder. Include the libraries in libs/ individually in the build path. BTW, you may want to bring in the android-support-v4 library to get Ice Cream Sandwich support instead of the Honeycomb support library. ...
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Get Root Directory Path of a PHP project

...IR gets the directory of the current file not the project root unless you call it in a file that is in the project root, but as php doesn't have the concept of a project all paths have to be absolute or relative to the current location – MikeT Nov 12 '19 at 14...