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Are Java static initializers thread safe?
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Yes, Java static initializers are thread safe (use your first option).
However, if you want to ensure that the code is executed exactly once you need to make sure that the class is only loaded by a single class-loader. Static ini...
When to use AtomicReference in Java?
...ing synchronized. In general, you're better off using synchronizers or the java.util.concurrent framework rather than bare Atomic* unless you know what you're doing.
Two excellent dead-tree references which will introduce you to this topic:
Herlihy's excellent Art of Multiprocessor Programming...
How to for each the hashmap? [duplicate]
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Lambda Expression Java 8
In Java 1.8 (Java 8) this has become lot easier by using forEach method from Aggregate operations(Stream operations) that looks similar to iterators from Iterable Interface.
Just copy paste below statement to your ...
Get keys from HashMap in Java
I have a Hashmap in Java like this:
14 Answers
14
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Understanding Spliterator, Collector and Stream in Java 8
I am having trouble understanding the Stream interface in Java 8, especially where it has to do with the Spliterator and Collector interfaces. My problem is that I simply can't understand Spliterator and the Collector interfaces yet, and as a result, the Stream interface is still somewha...
NullPointerException in Java with no StackTrace
I've had instances of our Java code catch a NullPointerException , but when I try to log the StackTrace (which basically ends up calling Throwable.printStackTrace() ), all I get is:
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Using the “final” modifier whenever applicable in Java [closed]
In Java, there is a practice of declaring every variable (local or class), parameter final if they really are.
25 Answers
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Retrieve version from maven pom.xml in code
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Assuming you're using Java, you can:
Create a .properties file in (most commonly) your src/main/resources directory (but in step 4 you could tell it to look elsewhere).
Set the value of some property in your .properties file using the standard M...
How to specify JVM maximum heap size “-Xmx” for running an application with “run” action in SBT?
...rays processing and needs more memory than JVM gives by default. I know in Java it's specified by "-Xmx" option. How do I set SBT up to use particular "-Xmx" value to run an application with "run" action?
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Using Java 8's Optional with Stream::flatMap
The new Java 8 stream framework and friends make for some very concise java code, but I have come across a seemingly-simple situation that is tricky to do concisely.
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