what is the difference between fail-fast and fail-safe iterators in java?
231004
Fail-safe iterators means they will not throw any exception even if the collection is modified while iterating over it. Whereas Fail-fast iterators throw an exception(ConcurrentModificationException) if the collection is modified while iterating over it.
60563
try has almost no expense at all. Instead of doing the work of setting up the try at runtime, the code's metadata is structured at compile time such that when an exception is thrown, it now does a relatively expensive operation of walking up the stack and seeing if any try blocks exist that would catch this exception.
415418
Iterator is an interface. It is not a class. It is used to iterate through each and every element in a list. Iterator is implemented Iterator design pattern.
313593
All collection classes (except Vector and Hashtable) in the java. util package are not thread-safe. The only two legacy collections are thread-safe: Vector and Hashtable. ... This is how you can synchronise a list in java.
1091715
In general no. If the Spliterator used has the CONCURRENT characteristic, then the stream is thread-safe. The stream API defines numerous contracts for each step of the pipeline, if any of them are violated then unpredictable behavior or exception may happen.
1183480
NOTE: ToArray() is similar to ToList() but returning an array instead of a list and I included it in the benchmarks. Not surprisingly all the implementations are O(n), meaning the processing time increases with the number of items in the sequence. Surprisingly, ToArray() is faster than not using any conversion.
1032950
In general, in today's implementations, entering a try block is not expensive at all (this was not always true). However, throwing and handling an exception is usually a relatively expensive operation. So, exceptions should normally be used for exceptional events, not normal flow control.
375019
Using Iterator can be used on any collection and since it doesn't have to be thread safe there is no additional locking overhead. In the example of the micro-benchmark given, the reason the Enumeration is faster than Iterator is because it is tested first. ;)
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An iterator is any object that, pointing to some element in a range of elements (such as an array or a container), has the ability to iterate through the elements of that range using a set of operators (with at least the increment ( ++ ) and dereference ( * ) operators).
1376389
There IS a difference guys. DIE() can be used with other failable functions whereas echoing would need to caught as an error or exception.
1049853
Nested loops are not a bad thing per se. They are only bad, if there are used for problems, for which better algorithm have been found (better and bad in terms of efficiency regarding the input size).
1131912
Actually, list comprehension is much clearer and faster than filter+lambda, but you can use whichever you find easier. ... x then the list comprehension runs in a separate function so it will also be accessing the value through the closure and this difference won't apply.
1114196
The each method is meant to be an immutable iterator, where as the map method can be used as an iterator, but is really meant to manipulate the supplied array and return a new array. Another important thing to note is that the each function returns the original array while the map function returns a new array.
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First() is slightly more efficient because it doesn't bother checking to see if there is a second item. The only difference is that Single() expects there to be only one item in the enumeration to begin with, and will throw an exception if there are more than one. You use .
648622
Time complexity for ArrayDeque for accessing a element is O(1) and that for LinkList is is O(N) to access last element. ArrayDeque is not thread safe so manually synchronization is necessary so that you can access it through multiple threads and so they they are faster.
260588
Yes; all of the methods on the Atomic* classes are thread-safe. The difference between decrementAndGet() and getAndDecrement() is which value it returns. Saying " AtomicInteger is thread-safe" means that each thread calling for example value. No other guarantees.
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6 Answers. Actually immutable objects are always thread-safe, but its references may not be. Going back to basic: Thread-safe simply means that two or more threads must work in coordination on the shared resource or object. They shouldn't over-ride the changes done by any other thread.