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Looking for simple Java in-memory cache [closed]
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Then use ConcurrentHashMap<WeakReference<T>>. docs.oracle.com/javase/7/docs/api/java/lang/ref/…
– jdmichal
Sep 22 '16 at 18:23
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ExecJS and could not find a JavaScript runtime
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In your Gem file, write
gem 'execjs'
gem 'therubyracer'
and then run
bundle install
Everything works fine for me :)
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Key existence check in HashMap
...map.containsKey(key)) doSomethingWith(map.get(key))
all over the place ? Then you should simply check whether map.get(key) returned null and that's it.
By the way, HashMap doesn't throw exceptions for missing keys, it returns null instead. The only case where containsKey is needed is when you're s...
Convert datetime object to a String of date only in Python
...ness' sake: you can also directly access the attributes of the object, but then you only get the numbers:
'%s/%s/%s' % (dt.month, dt.day, dt.year)
The time taken to learn the mini-language is worth it.
For reference, here are the codes used in the mini-language:
%a Weekday as locale’s abb...
Mailto links do nothing in Chrome but work in Firefox?
...nt Settings->Manage Handlers...
If "email" is not listed on that page, then see this answer regarding how to proceed.
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Qt: can't find -lGL error
...4.x and 15.x, might work for later versions)
First locate the GL library
Then link it under /usr/lib
If the library is missing, it can be installed via libgl1-mesa-dev package
Here is how you could do this:
$ locate libGL
/usr/lib/i386-linux-gnu/mesa/libGL.so.1
/usr/lib/i386-linux-gnu/mesa/libG...
What exactly is Java EE?
...pecific classes such as org.jboss.wildfly.*, com.sun.glassfish.*, etc) and then we'll be able to run our code on any implementation (thus, on any application server). If you're familiar with JDBC, it's basically the same concept as how JDBC drivers work. See also a.o. In simplest terms, what is a fa...
List vs List
...t just in case, here it goes:
Covariance
If you have a class Automobile, then Car and Truck are their subtypes. Any Car can be assigned to a variable of type Automobile, this is well-known in OO and is called polymorphism. Covariance refers to using this same principle in scenarios with generics o...
What is cardinality in MySQL?
...ity of that set is |3|.
If set "A" contains 5 values A={10,21,33,42,57}, then the cardinality is |5|.
What that means in the context of mysql is that the cardinality of a table column is the count of that column's unique values. If you are looking at the cardinality of your primary key column (e...
Check if a value exists in ArrayList
...verride the equals() and hashCode() methods. If you are using Eclipse IDE, then you can have these methods generated by first opening the source file for your CurrentAccount object and the selecting Source > Generate hashCode() and equals()...
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