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Initialization of an ArrayList in one line
...or later, after List.of() was added:
List<String> strings = List.of("foo", "bar", "baz");
With Java 10 or later, this can be shortened with the var keyword.
var strings = List.of("foo", "bar", "baz");
This will give you an immutable List, so it cannot be changed.
Which is what you want in mo...
How to convert a PIL Image into a numpy array?
...to a numpy array this way:
import numpy
import PIL
img = PIL.Image.open("foo.jpg").convert("L")
imgarr = numpy.array(img)
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Given a class, see if instance has method (Ruby)
...d
then read this:
In Ruby, a property (attribute) on your model is basically a method also. So method_defined? will also return true for properties, not just methods.
For example:
Given an instance of a class that has a String attribute first_name:
<instance>.first_name.class #=> Stri...
How do you assert that a certain exception is thrown in JUnit 4 tests?
...t can use JUnit 4.7, you can use the ExpectedException Rule:
public class FooTest {
@Rule
public final ExpectedException exception = ExpectedException.none();
@Test
public void doStuffThrowsIndexOutOfBoundsException() {
Foo foo = new Foo();
exception.expect(IndexOutOfBoundsExcepti...
Expression Versus Statement
...as one unit of execution, a thing that you did. The only reason it wasn't called a "line" was because sometimes it spanned multiple lines. An expression on its own couldn't do anything... you had to assign it to a variable.
1 + 2 / X
is an error in FORTRAN, because it doesn't do anything. You had...
Is there a literal notation for an array of symbols?
...
Yes! This is possible now in Ruby 2.0.0. One way to write it is:
%i{foo bar} # => [:foo, :bar]
You can also use other delimiters, so you could also write %i(foo bar) or %i!foo bar! for example.
This feature was originally announced here:
http://www.ruby-lang.org/zh_TW/news/2012/11/02/...
What is the proper way to check if a string is empty in Perl?
... situation where you haven't already guarded against undef, then the catch-all for "non-empty" that won't warn is if (defined $str and length $str).
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How do I compare strings in Java?
I've been using the == operator in my program to compare all my strings so far.
However, I ran into a bug, changed one of them into .equals() instead, and it fixed the bug.
...
ignoring any 'bin' directory on a git project
... mean zero or more sub-directories (see release notes).
The way to ignore all directories called bin anywhere below the current level in a directory tree is with a .gitignore file with the pattern:
bin/
In the man page, there an example of ignoring a directory called foo using an analogous patte...
JavaScript: Class.method vs. Class.prototype.method
... are extending the constructor function prototype, it will be available to all the object instances created with the new keyword, and the context within that function (the this keyword) will refer to the actual object instance where you call it.
Consider this example:
// constructor function
funct...