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What does 'synchronized' mean?
...hout the synchronized keyword, your thread 1 may not see the change thread 2 made to foo, or worse, it may only be half changed. This would not be what you logically expect.
Again, this is a non-trivial topic in Java. To learn more, explore topics here on SO and the Interwebs about:
Concurrenc...
Which is faster: while(1) or while(2)?
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23 Answers
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Immutable vs Mutable types
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233
What? Floats are immutable? But can't I do
x = 5.0
x += 7.0
print x # 12.0
Doesn't that "mu...
Gradle store on local file system
...downloaded jar files on the local file system? Maven stores them in the .m2 directory under USER_HOME , but where does Gradle store them? I checked the .gradle folder there, but saw only compiled scripts.
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How to extract numbers from a string and get an array of ints?
...p = Pattern.compile("-?\\d+");
Matcher m = p.matcher("There are more than -2 and less than 12 numbers here");
while (m.find()) {
System.out.println(m.group());
}
... prints -2 and 12.
-? matches a leading negative sign -- optionally. \d matches a digit, and we need to write \ as \\ in a Java ...
Index all *except* one item in python
...lement:
a = range(10)[::-1] # [9, 8, 7, 6, 5, 4, 3, 2, 1, 0]
b = [x for i,x in enumerate(a) if i!=3] # [9, 8, 7, 5, 4, 3, 2, 1, 0]
This is very general, and can be used with all iterables, including numpy arrays. If you replace [] with (), b will be an iterator instead of...
echo that outputs to stderr
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You could do this, which facilitates reading:
>&2 echo "error"
>&2 copies file descriptor #2 to file descriptor #1. Therefore, after this redirection is performed, both file descriptors will refer to the same file: the one file descriptor #2 was originally referri...
Pairs from single list
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52
My favorite way to do it:
from itertools import izip
def pairwise(t):
it = iter(t)
ret...
What is the most efficient/elegant way to parse a flat table into a tree?
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462
Now that MySQL 8.0 supports recursive queries, we can say that all popular SQL databases support...
Testing whether a value is odd or even
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22 Answers
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