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Why is there no Tree class in .NET?
The base class library in .NET has some excellent data structures for collections (List, Queue, Stack, Dictionary), but oddly enough it does not contain any data structures for binary trees. This is a terribly useful structure for certain algorithms, such as those that take advantage of different tr...
Immutable vs Unmodifiable collection
...ce to the unmodifiable collection, you can't rely on the contents not changing.
An immutable collection guarantees that nothing can change the collection any more. If it wraps a modifiable collection, it makes sure that no other code has access to that modifiable collection. Note that although no c...
Difference between JSONObject and JSONArray
After having a short look at Google I found this link that describes the difference, yet from a syntax point of view.
8 A...
Android Studio/Intellij Idea: “Table of Contents” for a class
I have been messing around with Android Studio and so far I like most of what I have seen. One thing that has been annoying me though is this lack of "Table of Contents" for a class. I apologize for not knowing exactly what to call it. But what I am referring to is the dropdown menu in eclipse that ...
What is the difference between UNION and UNION ALL?
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UNION removes duplicate records (where all columns in the results are the same), UNION ALL does not.
There is a performance hit when using UNION instead of UNION ALL, since the database server must do additional work to remove the duplicate rows, but usually you do not want ...
iOS - Calling App Delegate method from ViewController
What I am trying to do is click a button (that was created in code) and have it call up a different view controller then have it run a function in the new view controller.
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Deleting an object in java?
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You should remove the references to it by assigning null or leaving the block where it was declared. After that, it will be automatically deleted by the garbage collector (not immediately, but eventually).
Example 1:
Object a = new Object();
a = null; // after this, if t...
Filter data.frame rows by a logical condition
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To select rows according to one 'cell_type' (e.g. 'hesc'), use ==:
expr[expr$cell_type == "hesc", ]
To select rows according to two or more different 'cell_type', (e.g. either 'hesc' or 'bj fibroblast'), use %in%:
expr[expr$cell_type %in% c("...
Android update activity UI from service
I have a service which is checking for new task all the time. If there is new task, I want to refresh the activity UI to show that info.
I did find https://github.com/commonsguy/cw-andtutorials/tree/master/18-LocalService/ this example. Is that a good approch ? Any other examples?
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Get dimension from XML and set text size in runtime
In dimens.xml, I have:
3 Answers
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