java 8 functional programming book

Original December 25, 2016 10:02:52 Label: Functional Programming/ Java 3250 Describes the:supplierSource:public interface Supplier/** * Gets a result. * * @return a result */ T get();} 1 2 3 4 5 6 7 8 9 Test code:@Te

Programming | Function Note: When you read this article, I hope you can understand and understand the Java Generic (paradigm). Note: In the FP for Javaparty this weekend, many people seem to have no interest in FP and think that the FP in Java is not very useful. In fact, this is a very large concept of error, paradigm of the development of

I. OverviewA collection is a tool that our Java programmers need every day, and without a collection, Java programmers can hardly do anything, and our daily work is doing different things to the collection.Although the functionality of the collection is strong enough, when we are faced with complex business problems, it becomes disgusting to take advantage of the primitive collection operations.So the lambd

This series of articles translates from functional programming in Java Venkat Subramaniam Chapter II: The use of collections We often use a variety of collections, numbers, strings, and objects. They are everywhere, even if the code to operate a set can be slightly optimized, it can make the code a lot clearer. In this chapter, we explore how to use lamb

serial and difficult to parallelization.2. Such a cycle is not polymorphic; the income is the demand. Instead of using a method (which supports polymorphism) to perform a specific operation, we pass the collection directly to the for loop rather than to the collection.3. From the design level, the code written in this way violates the "Tell,don ' t ask" principle. Instead of leaving the iterations to the underlying library, we ask for an iteration to execute. It's time to switch from the old i

collection returned by Pollevents to a Java 8 stream and then used its internal iterator to print out detailed updates for each file. Let's run this code and then modify the Sample.txt file in the current directory to see if the program can detect the update. Copy Code code as follows: The "any" file changed within next 1 minute ... Sample.txt When we modify this file, the pro

Listing files in a directory The list () method of the file class makes it easy to list the file names of all the files in the directory. You can use its listfiles () method if you want to get a file, not just a filename. This is very simple and difficult is how to deal with the return of the list. Instead of using the traditional verbose external iterator, we use elegant functional expressions to actually traverse the list. Here we also have to use

status NBSP; lock Type advantages cons applicable range biased lock locking, unlocked unwanted amount External consumption thread competition when there is additional lock cancellation consumption Only one thread accesses the scene of the synchronization block lightweight lock competing threads do not block and incr

Conversion of lists Converting a collection into a new set is as simple as traversing it. Let's say we want to convert the names in the list to uppercase. Let's see what we can achieve. The string in Java is immutable, so it cannot be changed. We can generate new strings to replace the elements in the list. In this case, however, the original list is gone; there is a problem, the original list may also be immutable, such as Arrays.aslist () generate

then pass this reference to the filter method; this can easily avoid code redundancy. Let's refactor the previous Code to make it conform to the DRY principle. (Don't Repeat Yoursef -- DRY -- principle, see The Pragmatic Programmer: From Journeyman to Master [HT00],A book ). final Predicate startsWithN = name -> name.startsWith(N);final long countFriendsStartN =friends.stream().filter(startsWithN).count();final long countEditorsStartN =editor

implementation of the predicate test method. Now we can make it more explicit for the Java compiler to generate this method, rather than reproducing it in the location where the parameter is defined. In the example above, we can explicitly store a lambda expression in a predicate type reference, and then pass the reference to the filter method, which is easy to avoid code redundancy. Let's refactor the previous code to conform to the dry principle.

Implement Comparator interface The comparator interface can be found everywhere in the JDK library, from lookup to sorting, to reverse operation, and so on. Java 8 It becomes a functional interface, the advantage of which is that we can use the flow syntax to implement the comparator. We use several different ways to realize comparator and see the value of new

have to check the results before we can print. So little task to write such a long code. Let's re-examine the problem. We just want to be able to pick the first matching element and be able to safely handle a situation where there is no such element. Let's rewrite this pickname method with a lambda expression. Copy Code code as follows: public static void Pickname ( Final listFinal optionalNames.stream () . Filter (name->name.startswith (startingletter)) . FindFirst ();

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easier to maintain. Java code redundancy is also well known, and most attacks to the Java language will directly target Java's tedious and rigid syntax (but I think this is also one of the advantages of Java, as mentioned in the first section of this book, "conservative design ideas are the biggest advantage of