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Avoid synchronized(this) in Java?
...angerous. You've now introduced a client-side (user's of this class) lock ordering requirement. If two threads are calling method1() and method2() in a different order, they are likely to deadlock, but the user of this class has no idea that this is the case.
– daveb
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How to add a button dynamically in Android?
...d(R.id.buttonlayout);
LayoutParams lp = new LayoutParams(LayoutParams.MATCH_PARENT, LayoutParams.WRAP_CONTENT);
ll.addView(myButton, lp);
Have a look to this example
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How can strings be concatenated?
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The easiest way would be
Section = 'Sec_' + Section
But for efficiency, see: https://waymoot.org/home/python_string/
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How do I check if I'm running on Windows in Python? [duplicate]
...lue cannot be determined.
If that isn't working, maybe try platform.win32_ver and if it doesn't raise an exception, you're on Windows; but I don't know if that's forward compatible to 64-bit, since it has 32 in the name.
win32_ver(release='', version='', csd='', ptype='')
Get additional ...
Hidden features of C
...ints to the compiler (common in the Linux kernel)
#define likely(x) __builtin_expect((x),1)
#define unlikely(x) __builtin_expect((x),0)
see: http://kerneltrap.org/node/4705
What I like about this is that it also adds some expressiveness to some functions.
void foo(int arg)
{
if (...
List of lists changes reflected across sublists unexpectedly
...at you create a new list at each position. One way to do it is
[[1]*4 for _ in range(3)]
which will reevaluate [1]*4 each time instead of evaluating it once and making 3 references to 1 list.
You might wonder why * can't make independent objects the way the list comprehension does. That's beca...
What does |= (ior) do in Python?
...s1 |= s2 # 2
>>> s1.__ior__(s2) # 3
where the final value of s1 is equivalent either by:
an assigned OR operation
an in-place OR operation
an in-place OR operation via special method++
Example
Here we a...
How to access object attribute given string corresponding to name of that attribute
...ay prefer to use a generalized getter method like so:
class Test:
def __init__(self):
self.attr1 = 1
self.attr2 = 2
def get(self,varname):
return getattr(self,varname)
t = Test()
x = "attr1"
print ("Attribute value of {0} is {1}".format(x, t.get(x)))
Outputs:
At...
Hide keyboard when scroll UITableView
...to our UITableViewController class
override func scrollViewDidScroll(_ scrollView: UIScrollView) {
if !tableView.isDecelerating {
view.endEditing(true)
}
}
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How do I get the n-th level parent of an element in jQuery?
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Since parents() returns the ancestor elements ordered from the closest to the outer ones, you can chain it into eq():
$('#element').parents().eq(0); // "Father".
$('#element').parents().eq(2); // "Great-grandfather".
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