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In Hibernate Validator 4.1+, what is the difference between @NotNull, @NotEmpty, and @NotBlank?
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@NotEmpty: The CharSequence, Collection, Map or Array object is not null and size > 0.
@NotBlank: The string is not null and the trimmed length is greater than zero.
To help you understand, let's look into how these constraints are defined and carried out (I'm using version 4.1):
The @Not...
Hidden Features of Java
...e per-thread state.
Since JDK 1.5 Java has had extremely well implemented and robust concurrency tools beyond just locks, they live in java.util.concurrent and a specifically interesting example is the java.util.concurrent.atomic subpackage that contains thread-safe primitives that implement the co...
Python (and Python C API): __new__ versus __init__
...stion I'm about to ask seems to be a duplicate of Python's use of __new__ and __init__? , but regardless, it's still unclear to me exactly what the practical difference between __new__ and __init__ is.
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Why does one hot encoding improve machine learning performance?
...ced that when One Hot encoding is used on a particular data set (a matrix) and used as training data for learning algorithms, it gives significantly better results with respect to prediction accuracy, compared to using the original matrix itself as training data. How does this performance increase h...
Generating CSV file for Excel, how to have a newline inside a value
...ot strip off leading spaces. You will get unwanted spaces in your headings and data fields. Worse, the " that should be "protecting" that line-break in the third column will be ignored because it is not at the start of the field.
If you have non-ASCII characters (encoded in UTF-8) in the file, you ...
Downloading jQuery UI CSS from Google's CDN
I am planning on using Google to download the jQuery lib for both UI and Core. My question is, do they allow me to download the CSS for it or should I have to host it myself?
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Difference between size_t and std::size_t
What are the differences between size_t and std::size_t in terms of where they are declared, when they should be used and any other differentiating features?
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What is time_t ultimately a typedef to?
I searched my Linux box and saw this typedef:
10 Answers
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What is the difference between setUp() and setUpClass() in Python unittest?
What is the difference between setUp() and setUpClass() in the Python unittest framework? Why would setup be handled in one method over the other?
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How to read from a file or STDIN in Bash?
...e following Perl script ( my.pl ) can read from either the file on the command line args or from STDIN:
15 Answers
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