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How do MySQL indexes work?
I am really interested in how MySQL indexes work, more specifically, how can they return the data requested without scanning the entire table?
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Purpose of buildscript block in Gradle
...u can use everything that ships with Gradle out-of-the-box. If you additionally want to use third-party plugins, task classes, or other classes (in the build script!), you have to specify the corresponding dependencies in the buildScript block.
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Android: How can I get the current foreground activity (from a service)?
...atePendingResult()) that the service invokes
Have the activity register a callback or listener object with the service via bindService(), and have the service call an event method on that callback/listener object
Send an ordered broadcast Intent to the activity, with a low-priority BroadcastReceiver...
How to check if an int is a null
I have an object called Person .
8 Answers
8
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How can I find the current OS in Python? [duplicate]
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I usually use sys.platform (docs) to get the platform. sys.platform will distinguish between linux, other unixes, and OS X, while os.name is "posix" for all of them.
For much more detailed information, use the platform module. Th...
What is reflection and why is it useful?
... say you have an object of an unknown type in Java, and you would like to call a 'doSomething' method on it if one exists. Java's static typing system isn't really designed to support this unless the object conforms to a known interface, but using reflection, your code can look at the object and fin...
How much size “Null” value takes in SQL Server
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The smallest addressable unit of memory in most computer systems is one byte (typically 8 bits). So in reality, a bit takes a byte. Great answer Mark: +1.
– JohnB
Sep 16 '10 at 22:23
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How do I get the RootViewController from a pushed controller?
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:) ty. It still seems hacky - :) I really wanted an "official" member to do the job, something like self.navigationController.rootViewController, but alas, no such thing..
– bobobobo
Nov 25 '09 at 2:21
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Give examples of functions which demonstrate covariance and contravariance in the cases of both over
...List<? super String> contravariantList = aList;
You can now access all methods of covariantList that doesn't take a generic parameter (as it must be something "extends Object"), but getters will work fine (as the returned object will always be of type "Object")
The opposite is true for cont...
How to remove the last character from a string?
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replace will replace all instances of a letter. All you need to do is use substring():
public String method(String str) {
if (str != null && str.length() > 0 && str.charAt(str.length() - 1) == 'x') {
str = str.subs...