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List of standard lengths for database fields
I'm designing a database table and once again asking myself the same stupid question: How long should the firstname field be?
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Volatile boolean vs AtomicBoolean
...ranteed that every method is "atomic".
Thus, if you use an AtomicInteger and getAndAdd(int delta), you can be sure that the result will be 10. In the same way, if two threads both negate a boolean variable concurrently, with an AtomicBoolean you can be sure it has the original value afterwards, wi...
What is the difference between print and puts?
For example in this line of code I wrote, print and puts produce different results.
6 Answers
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How to create and handle composite primary key in JPA
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You can make an Embedded class, which contains your two keys, and then have a reference to that class as EmbeddedId in your Entity.
You would need the @EmbeddedId and @Embeddable annotations.
@Entity
public class YourEntity {
@EmbeddedId
private MyKey myKey;
@Column(name ...
How do I use disk caching in Picasso?
I am using Picasso to display image in my android app:
9 Answers
9
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Where do I find the current C or C++ standard documents?
For many questions the answer seems to be found in "the standard". However, where do we find that? Preferably online.
12 An...
Why is 128==128 false but 127==127 is true when comparing Integer wrappers in Java?
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When you compile a number literal in Java and assign it to a Integer (capital I) the compiler emits:
Integer b2 =Integer.valueOf(127)
This line of code is also generated when you use autoboxing.
valueOf is implemented such that certain numbers are "pooled", and i...
Bash script absolute path with OS X
...ction that'll do the job, but I'm not seeing anything available on the command-line. Here's a quick and dirty replacement:
#!/bin/bash
realpath() {
[[ $1 = /* ]] && echo "$1" || echo "$PWD/${1#./}"
}
realpath "$0"
This prints the path verbatim if it begins with a /. If not it must b...
Are arrays in PHP copied as value or as reference to new variables, and when passed to functions?
...e
copying. Use the reference operator to
copy an array by reference.
And the given example :
<?php
$arr1 = array(2, 3);
$arr2 = $arr1;
$arr2[] = 4; // $arr2 is changed,
// $arr1 is still array(2, 3)
$arr3 = &$arr1;
$arr3[] = 4; // now $arr1 and $arr3 are the same
?>
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What's the best way of implementing a thread-safe Dictionary?
...e to implement a thread-safe Dictionary in C# by deriving from IDictionary and defining a private SyncRoot object:
8 Answer...