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Do I need elements in persistence.xml?
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The persistence.xml has a jar-file that you can use. From the Java EE 5 tutorial:
<persistence>
<persistence-unit name="OrderManagement">
<description>This unit manages orders and customers.
It does not rely on any vendor-specific features and...
How to count the number of occurrences of an element in a List
I have an ArrayList , a Collection class of Java, as follows:
22 Answers
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Google Guava vs. Apache Commons [closed]
I was looking for a bidirectional map implementation in Java, and stumbled upon these two libraries:
5 Answers
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Java Synchronized Block for .class
What does this java code mean? Will it gain lock on all objects of MyClass ?
4 Answers
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Iterating through a Collection, avoiding ConcurrentModificationException when removing objects in a
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With Java 8 you can use the new removeIf method. Applied to your example:
Collection<Integer> coll = new ArrayList<>();
//populate
coll.removeIf(i -> i == 5);
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When should I use File.separator and when File.pathSeparator?
...le part is implied. But who knows why they did a lot of what they did with Java.
– user489041
Dec 21 '16 at 17:34
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Is there a performance difference between a for loop and a for-each loop?
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From Item 46 in Effective Java by Joshua Bloch :
The for-each loop, introduced in
release 1.5, gets rid of the clutter
and the opportunity for error by
hiding the iterator or index variable
completely. The resulting idiom
applies equally...
Difference between final and effectively final
I'm playing with lambdas in Java 8 and I came across warning local variables referenced from a lambda expression must be final or effectively final . I know that when I use variables inside anonymous class they must be final in outer class, but still - what is the difference between final and ef...
Difference between wait() and sleep()
...it of missing information. Many people wrote down the definitions from the Javadoc and also the meaning of the two english words but I do not see Why I should ever use sleep instead of wait? What is the benchmarking and speed difference between the two? If I can do everything that I can do with sle...
Difference between Inheritance and Composition
...same?
If I want to implement the composition pattern, how can I do that in Java?
17 Answers
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