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What are the differences between LinearLayout, RelativeLayout, and AbsoluteLayout?
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LinearLayout means you can align views one by one (vertically/ horizontally).
RelativeLayout means based on relation of views from its parents and other views.
ConstraintLayout is similar to a RelativeLayout in that it uses relations to...
When to use ref and when it is not necessary in C#
...will be seen.
When a parameter (of any kind) is passed by reference, that means that any changes to the parameter are seen by the caller - changes to the parameter are changes to the variable.
The article explains all of this in more detail, of course :)
Useful answer: you almost never need to us...
Why don't Java Generics support primitive types?
...es are erased to their bounds as they are incorporated into bytecode. This means that whether a class is generic or not, it still compiles to a single class, with the same name, and whose member signatures are the same. Type safety is verified at compile time, and runtime is unfettered by the generi...
Auto-loading lib files in Rails 4
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Just remember that lib is meant for code that can be applied to multiple projects and might possibly be extracted to a gem. If not create a more appropriate folder under app search as services/ or presenters/ and even subdirs off these.
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Select distinct using linq [duplicate]
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myList.GroupBy(test => test.id)
.Select(grp => grp.First());
Edit: as getting this IEnumerable<> into a List<> seems to be a mystery to many people, you can simply write:
var result = myList.GroupBy(test => test.id)
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What do the f and t commands do in Vim?
... best explanation for the non-esoteric crowd. what does to [count]'th even mean?
– Tycholiz
Jan 6 at 6:51
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show 2 more comments
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Can I concatenate multiple MySQL rows into one field?
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You can use GROUP_CONCAT:
SELECT person_id, GROUP_CONCAT(hobbies SEPARATOR ', ')
FROM peoples_hobbies
GROUP BY person_id;
As Ludwig stated in his comment, you can add the DISTINCT operator to avoid duplicates:
SELECT person_id, GROUP_CONCAT(DISTINCT hobbies SEPARA...
how to exclude null values in array_agg like in string_agg using postgres?
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SQL Fiddle
select
id,
(select array_agg(a) from unnest(canonical_users) a where a is not null) canonical_users,
(select array_agg(a) from unnest(non_canonical_users) a where a is not null) non_canonical_users
from (
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Start an Activity with a parameter
I'm very new on Android development.
5 Answers
5
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How to Store Historical Data
...e exact same fields as FOO with the exception of an auto-incrementing HIST_ID. Every time FOO is updated, I perform an insert statement into FOO_Hist similar to: insert into FOO_HIST select * from FOO where id = @id .
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