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Split Java String by New Line
...'m trying to split text in a JTextArea using a regex to split the String by \n However, this does not work and I also tried by \r\n|\r|n and many other combination of regexes.
Code:
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Postgresql GROUP_CONCAT equivalent?
...ld, array_agg(value_field1), array_agg(value_field2)
FROM data_table
GROUP BY id_field
array_agg returns an array, but you can CAST that to text and edit as needed (see clarifications, below).
Prior to version 8.4, you have to define it yourself prior to use:
CREATE AGGREGATE array_agg (anyeleme...
What is the most efficient/elegant way to parse a flat table into a tree?
...d in the same table too. Read "Trees and Hierarchies in SQL for Smarties" by Joe Celko for a lot more information on these designs.
I usually prefer a design called Closure Table (aka "Adjacency Relation") for storing tree-structured data. It requires another table, but then querying trees is pre...
In mongoDb, how do you remove an array element by its index?
...
There is no straight way of pulling/removing by array index. In fact, this is an open issue http://jira.mongodb.org/browse/SERVER-1014 , you may vote for it.
The workaround is using $unset and then $pull:
db.lists.update({}, {$unset : {"interests.3" : 1 }})
db.lists...
Multiple “order by” in LINQ
I have two tables, movies and categories , and I get an ordered list by categoryID first and then by Name .
7 Answers...
Reason to Pass a Pointer by Reference in C++?
...
You would want to pass a pointer by reference if you have a need to modify the pointer rather than the object that the pointer is pointing to.
This is similar to why double pointers are used; using a reference to a pointer is slightly safer than using point...
Group by in LINQ
...basically want:
var results = from p in persons
group p.car by p.PersonId into g
select new { PersonId = g.Key, Cars = g.ToList() };
Or as a non-query expression:
var results = persons.GroupBy(
p => p.PersonId,
p => p.car,
(key, g) => new { Perso...
List vs Set vs Bag in NHibernate
...and Equals to indicate the business definition of duplicate. Can be sorted by defining an orderby or by defining a comparer resulting in a SortedSet result.
Bag: Unordered list of entities, duplicates allowed. Use a .NET ICollection<T> in code. The index column of the list is not mapped and no...
Understanding garbage collection in .NET
...ow the garbage collector discovers local variables and how that's affected by having a debugger present.
First off, the jitter performs two important duties when it compiles the IL for a method into machine code. The first one is very visible in the debugger, you can see the machine code with the ...
Service vs IntentService in the Android platform
...ded (Intent triggered tasks).
How to trigger?
The Service is triggered by calling method startService().
The IntentService is triggered using an Intent, it spawns a new worker thread and the method onHandleIntent() is called on this thread.
Triggered From
The Service and IntentService may be...