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What is the Java string pool and how is “s” different from new String(“s”)? [duplicate]
...allows string constants to be reused, which is possible because strings in Java are immutable. If you repeat the same string constant all over the place in your Java code, you can actually have only one copy of that string in your system, which is one of the advantages of this mechanism.
When you u...
Why Java needs Serializable interface?
...f this form makes the class internals part of the public API (which is why javadoc gives you the persisted forms of classes).
For long-term persistence, the class must be able to decode this form, which restricts the changes you can make to class design. This breaks encapsulation.
Serialization ca...
Which Java Collection should I use?
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@MattBall I agree with you for the most part. However Java LinkedList is a double linked list, so access at start and at end are both fast. You will note that of the branches above all three questions have to answer yes before I'd recommend using the LinkedList - so in other wor...
Java int to String - Integer.toString(i) vs new Integer(i).toString()
Sometimes java puzzles me.
I have a huge amount of int initializations to make.
11 Answers
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JPA or JDBC, how are they different?
I am learning Java EE and I downloaded the eclipse with glassfish for the same. I saw some examples and also read the Oracle docs to know all about Java EE 5. Connecting to a database was very simple. I opened a dynamic web project, created a session EJB , I used EntityManager and with the get meth...
String isNullOrEmpty in Java? [duplicate]
...d before, but Googling doesn't find it . Is there, in any of the standard java libraries (including apache/google/...), a static isNullOrEmpty() method for Strings ?
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IntelliJ not recognizing a particular file correctly, instead its stuck as a text file
... note for googlers happening upon this, I had the exact same issue (with a Java file) with the same resolution; IntelliJ 13. When trying to create the file, I encountered the error 'Unable to parse template "Interface" Selected class file name mapped to not java'. Couldn't find that error message an...
Java: Get first item from a collection
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In java 8:
Optional<String> firstElement = collection.stream().findFirst();
For older versions of java, there is a getFirst method in Guava Iterables:
Iterables.getFirst(iterable, defaultValue)
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How to sort an ArrayList?
I have a List of doubles in java and I want to sort ArrayList in descending order.
20 Answers
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Static nested class in Java, why?
I was looking at the Java code for LinkedList and noticed that it made use of a static nested class, Entry .
14 Answers
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