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What happens when a duplicate key is put into a HashMap?
...bject, that object becomes eligible for garbage collection. Additionally, Java returns any previous value associated with the given key (or null if none present), so you can determine what was there and maintain a reference if necessary.
More information here: HashMap Doc
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Why is it not possible to extend annotations in Java?
I don't understand why there is no inheritance in Java annotations, just as Java classes. I think it would be very useful.
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Does Java have something like C#'s ref and out keywords?
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No, Java doesn't have something like C#'s ref and out keywords for passing by reference.
You can only pass by value in Java. Even references are passed by value. See Jon Skeet's page about parameter passing in Java for more deta...
What is the best Java email address validation method? [closed]
What are the good email address validation libraries for Java? Are there any alternatives to commons validator ?
19 Answe...
Open Source Java Profilers [closed]
What can you guys recommend to use with Java?
12 Answers
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Retrieving a List from a java.util.stream.Stream in Java 8
I was playing around with Java 8 lambdas to easily filter collections. But I did not find a concise way to retrieve the result as a new list within the same statement. Here is my most concise approach so far:
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Truststore and Keystore Definitions
.... You can actually import a private key and a public certificate into the [java home]/jre/lib/security/cacerts default "truststore". The keytool utility does not make a distinction in the two terms, only in store types (i.e. - JKS vs. PKCS12). For that matter, Java does the same thing in the source ...
Java: Clear the console
Can any body please tell me what code is used for clear screen in Java? For example in C++
14 Answers
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How to initialize HashSet values by construction?
... Although most probably correct at the time of writing, as of Java 7 do use the Diamond operator as in: Set<String> h = new HashSet<>(Arrays.asList("a", "b")); public static final Set<String> MY_SET = new HashSet<>(Arrays.asList(SET_VALUES));
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List of Java class file format major version numbers?
I saw this list of major version numbers for Java in another post:
4 Answers
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