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Why does Java's hashCode() in String use 31 as a multiplier?
...iplying by 31 can be relatively cheap. On an ARM, for instance, it is only one instruction:
RSB r1, r0, r0, ASL #5 ; r1 := - r0 + (r0<<5)
Most other processors would require a separate shift and subtract instruction. However, if your multiplier is slow this is still a win. Modern p...
Case objects vs Enumerations in Scala
...
One big difference is that Enumerations come with support for instantiating them from some name String. For example:
object Currency extends Enumeration {
val GBP = Value("GBP")
val EUR = Value("EUR") //etc.
}
Then yo...
Class JavaLaunchHelper is implemented in both … libinstrument.dylib. One of the two will be used. Wh
...of my app. I'm still getting the same issue with the version you have mentioned above. though I've tried many 8 version with its patches in my mac os. No Luck.
– Sathish
May 10 '17 at 8:20
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Why an abstract class implementing an interface can miss the declaration/implementation of one of th
... it makes better sense to factor it into a separate base class (DRY trumps one-place-code)
– Gishu
Oct 13 '08 at 15:23
4
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Twitter oAuth callbackUrl - localhost development
Is anyone else having a difficult time getting Twitters oAuth's callback URL to hit their localhost development environment.
Apparently it has been disabled recently. http://code.google.com/p/twitter-api/issues/detail?id=534#c1
...
SQL: deleting tables with prefix
...
I have only one database so i wont need the 2nd one.
– Deniz Zoeteman
Oct 19 '09 at 15:38
4
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Was PreferenceFragment intentionally excluded from the compatibility package?
...rection is to use PreferenceFragment on Android 3.0 and higher.
Can anyone tell me whether this was intentional?
My guess is it's a question of engineering time, but that's just a guess.
If so, can I easily target a range of devices (i.e. < 3.0 and >=3.0) or will I have to jump thr...
Explicitly calling return in a function or not
...eturn') with that last value as an argument will do the same job but needs one call more. So that this (often) unnecessary .Primitive('return') call can draw additional resources.
Simple measurement however shows that the resulting difference is very small and thus can not be the reason for not us...
How does one make random number between range for arc4random_uniform()?
...al extension of either Int or Range. I would simply add this as a stand-alone function in a utilities file.
– Vince O'Sullivan
Nov 16 '15 at 9:31
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Group by multiple columns in dplyr, using string vector input
...= names(data)[-3]
library(dplyr)
df1 <- data %>%
group_by_at(vars(one_of(columns))) %>%
summarize(Value = mean(value))
#compare plyr for reference
df2 <- plyr::ddply(data, columns, plyr::summarize, value=mean(value))
table(df1 == df2, useNA = 'ifany')
## TRUE
## 27
The output ...