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Android emulator shows nothing except black screen and adb devices shows “device offline”
...tor comes up on the screen. But even after waiting for as long as 2-3 hrs, all it shows is a black screen. Not even the android home screen or the android logo. Just a black screen. And while initially "adb devices" shows the emulator as offline.after 2-3 minutes the list of attached devices becomes...
Why seal a class?
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Performance is an important factor for example, the string class in java is final(<- sealed) and reason for this is performance only.
I think another important point is to avoid the brittle base class problem described in detail here:
http://blogs.msdn.com/ericlippert/archi...
Automatic counter in Ruby for each?
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In this context, the %-sign operator is a method of the String class. You can read about it at ruby-doc.org/core/classes/String.html#M000770. Or you can type ri String#% at a command prompt. Or you can type ri % to see all of the documented classes that recognize it, e.g., the mor...
MySQL DISTINCT on a GROUP_CONCAT()
...swers to this question do not return what the OP needs, they will return a string like:
test1 test2 test3 test1 test3 test4
(notice that test1 and test3 are duplicated) while the OP wants to return this string:
test1 test2 test3 test4
the problem here is that the string "test1 test3" is duplic...
How to overcome “datetime.datetime not JSON serializable”?
...ult=json_util.default)
Example usage (deserialization):
json.loads(aJsonString, object_hook=json_util.object_hook)
Django
Django provides a native DjangoJSONEncoder serializer that deals with this kind of properly.
See https://docs.djangoproject.com/en/dev/topics/serialization/#djangojsonen...
Getting new Twitter API consumer and secret keys
...term "API key" usually refers to what's called an OAuth consumer key. This string identifies your application when making requests to the API. In OAuth 1.0a, your "API keys" probably refer to the combination of this consumer key and the "consumer secret," a string that is used to securely "sign" you...
How to generate a random int in C?
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Note: Don't use rand() for security. If you need a cryptographically secure number, see this answer instead.
#include <time.h>
#include <stdlib.h>
srand(time(NULL)); // Initialization, should only be called once.
int r = rand(); // Returns a pseudo-random integer bet...
Convert array of strings into a string in Java
I want the Java code for converting an array of strings into an string.
13 Answers
13
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Functional style of Java 8's Optional.ifPresent and if-not-Present?
...b")).ifPresent(this::print);
map() - transform value if present
opt.map(String::trim).filter(t -> t.length() > 1).ifPresent(this::print);
orElse()/orElseGet() - turning empty Optional to default T
int len = opt.map(String::length).orElse(-1);
int len = opt.
map(String::length).
o...
Objective-C: Where to remove observer for NSNotification?
...his is obviously not a satisfying answer.
I'd recommend, that you add a call [notificationCenter removeObserver: self] in method dealloc of those classes, which you intend to use as observers, as it is the last chance to unregister an observer cleanly. This will, however, only protect you against ...