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Java: Instanceof and Generics

...ok like this: if (arg0 != null && !(this.type.isAssignableFrom(arg0.getClass())) { return -1; } share | improve this answer | fo...
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Convert datetime to Unix timestamp and convert it back in python

...f your original naive datetime was UTC, the way to recover it is to use utcfromtimestamp instead of fromtimestamp. On the other hand, if your original naive datetime was local, you shouldn't have subtracted a UTC timestamp from it in the first place; use datetime.fromtimestamp(0) instead. Or, if y...
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How to get just the parent directory name of a specific file

How to get ddd from the path name where the test.java resides. 10 Answers 10 ...
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Sending Email in Android using JavaMail API without using the default/built-in app

...e mail. Cheers! P.S. And don't forget that you cannot do network operation from any Activity in android. Hence it is recommended to use AsyncTask or IntentService to avoid network on main thread exception. Jar files: https://code.google.com/archive/p/javamail-android/ ...
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How do I clone a Django model instance object and save it to the database?

...objects one by one. If you don't want the call to the database, just do: from copy import deepcopy new_instance = deepcopy(object_you_want_copied) new_instance.id = None new_instance.save() It does the same thing as some of these other answers, but it doesn't make the database call to retrieve ...
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How do I debug an MPI program?

...ce Analysis Tool (STAT). We use this at Livermore to collect stack traces from potentially hundreds of thousands of running processes and to represent them intelligently to users. It's not a full-featured debugger (a full-featured debugger would never scale to 208k cores), but it will tell you whi...
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how to get the last character of a string?

...thod. Just by: str.slice(-1); A negative start index slices the string from length+index, to length, being index -1, the last character is extracted: "abc".slice(-1); // "c"; share | improve t...
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How do I clear/delete the current line in terminal?

...y Ctrl+g Cancel the search and restore original line Ctrl+n Next command from the History Ctrl+p previous command from the History share | improve this answer | follow ...
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How is Math.Pow() implemented in .NET Framework?

... a look at the code requires the source code for the CLR. You can get that from the SSCLI20 distribution. It was written around the .NET 2.0 time frame, I've found the low-level implementations, like Math.Pow() to be still largely accurate for later versions of the CLR. The lookup table is located i...
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Why does ConcurrentHashMap prevent null keys and values?

... From the author of ConcurrentHashMap himself (Doug Lea): The main reason that nulls aren't allowed in ConcurrentMaps (ConcurrentHashMaps, ConcurrentSkipListMaps) is that ambiguities that may be just barely tolerable i...