Java 8 introduced several new features including lambda expressions, default methods in interfaces, streams API and others. Lambda expressions allow implementing functional interfaces using anonymous functions. Interfaces can now define default and static methods. The streams API allows performing bulk operations on collections in a declarative way. Some performance improvements in Java 8 include faster common data structures like HashMap, garbage collector improvements and enhanced fork/join framework.
Java is Object Oriented Programming. Java 8 is the latest version of the Java which is used by many companies for the development in many areas. Mobile, Web, Standalone applications.
Java 8 is coming soon. In this presentation I have outlined the major Java 8 features. You get information about interface improvements, functional interfaces, method references, lambdas, java.util.function, java.util.stream
Java is Object Oriented Programming. Java 8 is the latest version of the Java which is used by many companies for the development in many areas. Mobile, Web, Standalone applications.
Java 8 is coming soon. In this presentation I have outlined the major Java 8 features. You get information about interface improvements, functional interfaces, method references, lambdas, java.util.function, java.util.stream
In Java 8, the java.util.function has numerous built-in interfaces. Other packages in the Java library (notably java.util.stream package) make use of the interfaces defined in this package. Java 8 developers should be familiar with using key interfaces provided in this package. This presentation provides an overview of four key functional interfaces (Consumer, Supplier, Function, and Predicate) provided in this package.
Slides for a lightning talk on Java 8 lambda expressions I gave at the Near Infinity (www.nearinfinity.com) 2013 spring conference.
The associated sample code is on GitHub at https://github.com/sleberknight/java8-lambda-samples
Java 8 Stream API. A different way to process collections.David Gómez García
A look on one of the features of Java 8 hidden behind the lambdas. A different way to iterate Collections. You'll never see the Collecions the same way.
These are the slides I used on my talk at the "Tech Thursday" by Oracle in June in Madrid.
In this Meetup Victor Perepelitsky - R&D Technical Leader at LivePerson leading the 'Real Time Event Processing Platform' team , will talk about Java 8', 'Stream API', 'Lambda', and 'Method reference'.
Victor will clarify what functional programming is and how can you use java 8 in order to create better software.
Victor will also cover some pain points that Java 8 did not solve regarding functionality and see how you can work around it.
This presentation introduces some concepts about the Java Collection framework. These slides introduce the following concepts:
- Collections and iterators
- Linked list and array list
- Hash set and tree set
- Maps
- The collection framework
The presentation is took from the Java course I run in the bachelor-level informatics curriculum at the University of Padova.
In this core java training session, you will learn Collections - Maps. Topics covered in this session are:
• Collections – Maps
• Map Interface
• Map methods
• Mapuse
• Hashmap
• Treemap
• Utilities
For more information about this course visit on this link: https://www.mindsmapped.com/courses/software-development/learn-java-fundamentals-hands-on-training-on-core-java-concepts/
what is exception?
what is exception handling?
When occur Exception in a program?
Why we use exception handling macanisum?
explain try, catch, finally keywords.
try,catch and finally-Rules.
Types of Exception.
example of Some java Pre-defined /Built-in exception class.
User-defined Eceptions
Exception in java?
In Java 8, the java.util.function has numerous built-in interfaces. Other packages in the Java library (notably java.util.stream package) make use of the interfaces defined in this package. Java 8 developers should be familiar with using key interfaces provided in this package. This presentation provides an overview of four key functional interfaces (Consumer, Supplier, Function, and Predicate) provided in this package.
Slides for a lightning talk on Java 8 lambda expressions I gave at the Near Infinity (www.nearinfinity.com) 2013 spring conference.
The associated sample code is on GitHub at https://github.com/sleberknight/java8-lambda-samples
Java 8 Stream API. A different way to process collections.David Gómez García
A look on one of the features of Java 8 hidden behind the lambdas. A different way to iterate Collections. You'll never see the Collecions the same way.
These are the slides I used on my talk at the "Tech Thursday" by Oracle in June in Madrid.
In this Meetup Victor Perepelitsky - R&D Technical Leader at LivePerson leading the 'Real Time Event Processing Platform' team , will talk about Java 8', 'Stream API', 'Lambda', and 'Method reference'.
Victor will clarify what functional programming is and how can you use java 8 in order to create better software.
Victor will also cover some pain points that Java 8 did not solve regarding functionality and see how you can work around it.
This presentation introduces some concepts about the Java Collection framework. These slides introduce the following concepts:
- Collections and iterators
- Linked list and array list
- Hash set and tree set
- Maps
- The collection framework
The presentation is took from the Java course I run in the bachelor-level informatics curriculum at the University of Padova.
In this core java training session, you will learn Collections - Maps. Topics covered in this session are:
• Collections – Maps
• Map Interface
• Map methods
• Mapuse
• Hashmap
• Treemap
• Utilities
For more information about this course visit on this link: https://www.mindsmapped.com/courses/software-development/learn-java-fundamentals-hands-on-training-on-core-java-concepts/
what is exception?
what is exception handling?
When occur Exception in a program?
Why we use exception handling macanisum?
explain try, catch, finally keywords.
try,catch and finally-Rules.
Types of Exception.
example of Some java Pre-defined /Built-in exception class.
User-defined Eceptions
Exception in java?
Automatic Migration of Legacy Java Method Implementations to InterfacesRaffi Khatchadourian
Java 8 is one of the largest upgrades to the popular language and framework in over a decade. In this talk, I will first overview several new, key features of Java 8 that can help make programs easier to read, write, and maintain, especially in regards to collections. These features include Lambda Expressions, the Stream API, and enhanced interfaces, many of which help bridge the gap between functional and imperative programming paradigms and allow for succinct concurrency implementations. Next, I will discuss several open issues related to automatically migrating (refactoring) legacy Java software to use such features correctly, efficiently, and as completely as possible. Solving these problems will help developers to maximally understand and adopt these new features thus improving their software.
Cover Basic concept for Functional Programming in Java. Define new functional interfaces, lambda expressions, how to translate lambda expression, JVM deal with new byte code etc. This is not the perfect slides for functional programming, but trying cover simple basic functional programming.
The skeletal implementation pattern is a software design pattern consisting of defining an abstract class that provides a partial interface implementation. However, since Java allows only single class inheritance, if implementers decide to extend a skeletal implementation, they will not be allowed to extend any other class. Also, discovering the skeletal implementation may require a global analysis.
Java 8 enhanced interfaces alleviate these problems by allowing interfaces to contain (default) method implementations, which implementers inherit. Java classes are then free to extend a different class, and a separate abstract class is no longer needed; developers considering implementing an interface need only examine the interface itself.
In this talk, I will argue that both these benefits improve software modularity, and I will discuss our ongoing work in developing an automated refactoring tool that would assist developers in taking advantage of the enhanced interface feature for their legacy Java software.
Raffi Khatchadourian is an Assistant Professor in the Department of Computer Systems Technology (CST) at New York City College of Technology (NYCCT) of the City University of New York (CUNY) and an Open Educational Resources (OER) Fellow for the Spring 2016 semester. His research is centered on techniques for automated software evolution, particularly those related to automated refactoring and source code recommendation systems. His goal is to ease the burden associated with correctly and efficiently evolving large and complex software by providing automated tools that can be easily used by developers.
Raffi received his MS and PhD degrees in Computer Science from Ohio State University and his BS degree in Computer Science from Monmouth University in New Jersey. Prior to joining City Tech, he was a Software Engineer at Apple, Inc. in Cupertino, California, where he worked on Digital Rights Management (DRM) for iTunes, iBooks, and the App store. He also developed distributed software that tested various features of iPhones, iPads, and iPods.
Open Problems in Automatically Refactoring Legacy Java Software to use New Fe...Raffi Khatchadourian
Java 8 is one of the largest upgrades to the popular language and framework in over a decade. In this talk, I will first overview several new, key features of Java 8 that can help make programs easier to read, write, and maintain, especially in regards to collections. These features include Lambda Expressions, the Stream API, and enhanced interfaces, many of which help bridge the gap between functional and imperative programming paradigms and allow for succinct concurrency implementations. Next, I will discuss several open issues related to automatically migrating (refactoring) legacy Java software to use such features correctly, efficiently, and as completely as possible. Solving these problems will help developers to maximally understand and adopt these new features thus improving their software.
This presentaion provides and overview of the new features of Java 8, namely default methods, functional interfaces, lambdas, method references, streams and Optional vs NullPointerException.
This presentation by Arkadii Tetelman (Lead Software Engineer, GlobalLogic) was delivered at Java.io 3.0 conference in Kharkiv on March 22, 2016.
This Lambda Expression C# Tutorial will acquaint you with a clear understanding of the fundamentals of LINQ C#. In this C# Tutorial for beginners, you will get a better understanding of are Lambda Expression C# tutorial. We will begin our session with a discussion on Linq. Then we will discuss the Lambda Expression and Async Lambda. After that, we will look into Lambda in the standard query operators with an implementation. Now we will dive into the Type Interface. Then we will discuss the Variable scope. After that, we will have a look at the Expression tree. Finally, we will wind up this session with a conclusion.
Custom Healthcare Software for Managing Chronic Conditions and Remote Patient...Mind IT Systems
Healthcare providers often struggle with the complexities of chronic conditions and remote patient monitoring, as each patient requires personalized care and ongoing monitoring. Off-the-shelf solutions may not meet these diverse needs, leading to inefficiencies and gaps in care. It’s here, custom healthcare software offers a tailored solution, ensuring improved care and effectiveness.
Introducing Crescat - Event Management Software for Venues, Festivals and Eve...Crescat
Crescat is industry-trusted event management software, built by event professionals for event professionals. Founded in 2017, we have three key products tailored for the live event industry.
Crescat Event for concert promoters and event agencies. Crescat Venue for music venues, conference centers, wedding venues, concert halls and more. And Crescat Festival for festivals, conferences and complex events.
With a wide range of popular features such as event scheduling, shift management, volunteer and crew coordination, artist booking and much more, Crescat is designed for customisation and ease-of-use.
Over 125,000 events have been planned in Crescat and with hundreds of customers of all shapes and sizes, from boutique event agencies through to international concert promoters, Crescat is rigged for success. What's more, we highly value feedback from our users and we are constantly improving our software with updates, new features and improvements.
If you plan events, run a venue or produce festivals and you're looking for ways to make your life easier, then we have a solution for you. Try our software for free or schedule a no-obligation demo with one of our product specialists today at crescat.io
Graspan: A Big Data System for Big Code AnalysisAftab Hussain
We built a disk-based parallel graph system, Graspan, that uses a novel edge-pair centric computation model to compute dynamic transitive closures on very large program graphs.
We implement context-sensitive pointer/alias and dataflow analyses on Graspan. An evaluation of these analyses on large codebases such as Linux shows that their Graspan implementations scale to millions of lines of code and are much simpler than their original implementations.
These analyses were used to augment the existing checkers; these augmented checkers found 132 new NULL pointer bugs and 1308 unnecessary NULL tests in Linux 4.4.0-rc5, PostgreSQL 8.3.9, and Apache httpd 2.2.18.
- Accepted in ASPLOS ‘17, Xi’an, China.
- Featured in the tutorial, Systemized Program Analyses: A Big Data Perspective on Static Analysis Scalability, ASPLOS ‘17.
- Invited for presentation at SoCal PLS ‘16.
- Invited for poster presentation at PLDI SRC ‘16.
Do you want Software for your Business? Visit Deuglo
Deuglo has top Software Developers in India. They are experts in software development and help design and create custom Software solutions.
Deuglo follows seven steps methods for delivering their services to their customers. They called it the Software development life cycle process (SDLC).
Requirement — Collecting the Requirements is the first Phase in the SSLC process.
Feasibility Study — after completing the requirement process they move to the design phase.
Design — in this phase, they start designing the software.
Coding — when designing is completed, the developers start coding for the software.
Testing — in this phase when the coding of the software is done the testing team will start testing.
Installation — after completion of testing, the application opens to the live server and launches!
Maintenance — after completing the software development, customers start using the software.
Need for Speed: Removing speed bumps from your Symfony projects ⚡️Łukasz Chruściel
No one wants their application to drag like a car stuck in the slow lane! Yet it’s all too common to encounter bumpy, pothole-filled solutions that slow the speed of any application. Symfony apps are not an exception.
In this talk, I will take you for a spin around the performance racetrack. We’ll explore common pitfalls - those hidden potholes on your application that can cause unexpected slowdowns. Learn how to spot these performance bumps early, and more importantly, how to navigate around them to keep your application running at top speed.
We will focus in particular on tuning your engine at the application level, making the right adjustments to ensure that your system responds like a well-oiled, high-performance race car.
Top Features to Include in Your Winzo Clone App for Business Growth (4).pptxrickgrimesss22
Discover the essential features to incorporate in your Winzo clone app to boost business growth, enhance user engagement, and drive revenue. Learn how to create a compelling gaming experience that stands out in the competitive market.
Unleash Unlimited Potential with One-Time Purchase
BoxLang is more than just a language; it's a community. By choosing a Visionary License, you're not just investing in your success, you're actively contributing to the ongoing development and support of BoxLang.
First Steps with Globus Compute Multi-User EndpointsGlobus
In this presentation we will share our experiences around getting started with the Globus Compute multi-user endpoint. Working with the Pharmacology group at the University of Auckland, we have previously written an application using Globus Compute that can offload computationally expensive steps in the researcher's workflows, which they wish to manage from their familiar Windows environments, onto the NeSI (New Zealand eScience Infrastructure) cluster. Some of the challenges we have encountered were that each researcher had to set up and manage their own single-user globus compute endpoint and that the workloads had varying resource requirements (CPUs, memory and wall time) between different runs. We hope that the multi-user endpoint will help to address these challenges and share an update on our progress here.
Enhancing Research Orchestration Capabilities at ORNL.pdfGlobus
Cross-facility research orchestration comes with ever-changing constraints regarding the availability and suitability of various compute and data resources. In short, a flexible data and processing fabric is needed to enable the dynamic redirection of data and compute tasks throughout the lifecycle of an experiment. In this talk, we illustrate how we easily leveraged Globus services to instrument the ACE research testbed at the Oak Ridge Leadership Computing Facility with flexible data and task orchestration capabilities.
Software Engineering, Software Consulting, Tech Lead, Spring Boot, Spring Cloud, Spring Core, Spring JDBC, Spring Transaction, Spring MVC, OpenShift Cloud Platform, Kafka, REST, SOAP, LLD & HLD.
In 2015, I used to write extensions for Joomla, WordPress, phpBB3, etc and I ...Juraj Vysvader
In 2015, I used to write extensions for Joomla, WordPress, phpBB3, etc and I didn't get rich from it but it did have 63K downloads (powered possible tens of thousands of websites).
AI Fusion Buddy Review: Brand New, Groundbreaking Gemini-Powered AI AppGoogle
AI Fusion Buddy Review: Brand New, Groundbreaking Gemini-Powered AI App
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https://sumonreview.com/ai-fusion-buddy-review
AI Fusion Buddy Review: Key Features
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✅Use Gemini to Build high-converting Converting Sales Video Scripts, ad copies, Trending Articles, blogs, etc.100% unique!
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✅Fully automated AI articles bulk generation!
✅Auto-post or schedule stunning AI content across all your accounts at once—WordPress, Facebook, LinkedIn, Blogger, and more.
✅With one keyword or URL, generate complete websites, landing pages, and more…
✅Automatically create & sell AI content, graphics, websites, landing pages, & all that gets you paid non-stop 24*7.
✅Pre-built High-Converting 100+ website Templates and 2000+ graphic templates logos, banners, and thumbnail images in Trending Niches.
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See My Other Reviews Article:
(1) AI Genie Review: https://sumonreview.com/ai-genie-review
(2) SocioWave Review: https://sumonreview.com/sociowave-review
(3) AI Partner & Profit Review: https://sumonreview.com/ai-partner-profit-review
(4) AI Ebook Suite Review: https://sumonreview.com/ai-ebook-suite-review
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Atelier - Innover avec l’IA Générative et les graphes de connaissancesNeo4j
Atelier - Innover avec l’IA Générative et les graphes de connaissances
Allez au-delà du battage médiatique autour de l’IA et découvrez des techniques pratiques pour utiliser l’IA de manière responsable à travers les données de votre organisation. Explorez comment utiliser les graphes de connaissances pour augmenter la précision, la transparence et la capacité d’explication dans les systèmes d’IA générative. Vous partirez avec une expérience pratique combinant les relations entre les données et les LLM pour apporter du contexte spécifique à votre domaine et améliorer votre raisonnement.
Amenez votre ordinateur portable et nous vous guiderons sur la mise en place de votre propre pile d’IA générative, en vous fournissant des exemples pratiques et codés pour démarrer en quelques minutes.
Check out the webinar slides to learn more about how XfilesPro transforms Salesforce document management by leveraging its world-class applications. For more details, please connect with sales@xfilespro.com
If you want to watch the on-demand webinar, please click here: https://www.xfilespro.com/webinars/salesforce-document-management-2-0-smarter-faster-better/
Globus Compute wth IRI Workflows - GlobusWorld 2024Globus
As part of the DOE Integrated Research Infrastructure (IRI) program, NERSC at Lawrence Berkeley National Lab and ALCF at Argonne National Lab are working closely with General Atomics on accelerating the computing requirements of the DIII-D experiment. As part of the work the team is investigating ways to speedup the time to solution for many different parts of the DIII-D workflow including how they run jobs on HPC systems. One of these routes is looking at Globus Compute as a way to replace the current method for managing tasks and we describe a brief proof of concept showing how Globus Compute could help to schedule jobs and be a tool to connect compute at different facilities.
Utilocate offers a comprehensive solution for locate ticket management by automating and streamlining the entire process. By integrating with Geospatial Information Systems (GIS), it provides accurate mapping and visualization of utility locations, enhancing decision-making and reducing the risk of errors. The system's advanced data analytics tools help identify trends, predict potential issues, and optimize resource allocation, making the locate ticket management process smarter and more efficient. Additionally, automated ticket management ensures consistency and reduces human error, while real-time notifications keep all relevant personnel informed and ready to respond promptly.
The system's ability to streamline workflows and automate ticket routing significantly reduces the time taken to process each ticket, making the process faster and more efficient. Mobile access allows field technicians to update ticket information on the go, ensuring that the latest information is always available and accelerating the locate process. Overall, Utilocate not only enhances the efficiency and accuracy of locate ticket management but also improves safety by minimizing the risk of utility damage through precise and timely locates.
Globus Connect Server Deep Dive - GlobusWorld 2024Globus
We explore the Globus Connect Server (GCS) architecture and experiment with advanced configuration options and use cases. This content is targeted at system administrators who are familiar with GCS and currently operate—or are planning to operate—broader deployments at their institution.
OpenMetadata Community Meeting - 5th June 2024OpenMetadata
The OpenMetadata Community Meeting was held on June 5th, 2024. In this meeting, we discussed about the data quality capabilities that are integrated with the Incident Manager, providing a complete solution to handle your data observability needs. Watch the end-to-end demo of the data quality features.
* How to run your own data quality framework
* What is the performance impact of running data quality frameworks
* How to run the test cases in your own ETL pipelines
* How the Incident Manager is integrated
* Get notified with alerts when test cases fail
Watch the meeting recording here - https://www.youtube.com/watch?v=UbNOje0kf6E
5. Faster : Applications that have moved to Java 8 see some sort of speed improvement without
any specific work or tuning.
Less Code : A more functional style for the new APIs, focusing on WHAT you want to achieve
and not HOW to do it.
Easy to Parallelize : JVM splits operation into separate jobs and use fork/join to run them on
multiple cores
• parallelStream
Minimize Null Pointers
• Optional Type
5
6. Faster
Performance Improvements in Common Data Structures:
Benchmarks of the ever-popular HashMap show that performance is better in Java 8. No need to learn the new
Streams API or lambda syntax or even change the existing code to get speed improvements in your application.
Garbage Collector Improvements:
Poor garbage collection performance will impact an application’s performance. Java 8 has substantial changes to
GC that improve performance and simplify tuning. Removal of PermGen and the introduction of Metaspace.
Fork/Join Speed Improvements:
The fork/join framework was new in Java 7, and was the latest effort to simplify concurrent programming using
the JVM. A lot of work went into improving it further for Java 8. Fork/join is now the framework that’s used
under the covers for parallel operations in the Streams API.
6
9. Interface Improvements
Interfaces can now define static methods:
A common scenario in Java libraries is, for some interface 'XYZ ' there would be a companion utility class
'XYZUtility' with static methods for generating or working with XYZ instances. With the ability to define static
methods in the interfaces, in many cases the XYZUtility class can go away, with its public methods going on the
interface instead.
Interfaces can now define default methods (Defender Methods)
Prior to Java 8, it was essentially impossible for Java libraries to add methods to interfaces. Adding a method to
an interface would mean breaking all existing code that implements the interface. Now, as long as a sensible
default implementation of a method can be provided, library maintainers can add methods to these interfaces.
9
14. After introducing Default(Defender) Methods, it seems that interfaces and abstract
classes are same. However, they are still different concept in Java 8.
Abstract class can define constructor.
They are more structured and can have a state associated with them. While in
contrast, default method can be implemented only in the terms of invoking other
interface methods, with no reference to a particular implementation's state.
Abstract Classes can have fields that are not static and final, and define public,
protected, and private concrete methods.With interfaces, all fields are automatically
public, static, and final, and all methods that you declare or define (as default
methods) are public.
Abstract Class is object oriented while Interface is functionality oriented.
14
15. Functional Interfaces
Java has always been an Object Oriented Programming language. Everything in java
programming revolves around Objects
There is no way of defining just a function / method which stays in Java all by itself.
There is no way of passing a method as argument or returning a method body for that
instance.
15
16. In Java, a functional interface is basically an interface with a single abstract method.
This kind of interfaces are also known as SAM (Single Abstract Method) types.
An interface is considered a functional interface if it contains one and only one
abstract method with no default implementation
Examples??
java.lang.Runnable, java.awt.event.ActionListener, java.util.Comparator,
java.util.concurrent.Callable.
16
17. @FunctionalInterface
@FunctionalInterface is a new interface added in Java 8 to indicate that an interface
type declaration is intended to be a functional interface as defined by the Java
Language Specification.
@FunctionalInterface can be used for compiler level errors when the interface you
have annotated is not a valid Functional Interface.
@FunctionalInterface annotation is a facility to avoid accidental addition of abstract
methods in the functional interfaces.
17
19. Function<T, R> - take a T as input, return an R as ouput [R apply(T t)]
Predicate<T> - take a T as input, return a boolean as output [boolean test(T t)]
Consumer<T> - take a T as input, perform some action and don't return anything
[void accept(T t)]
Supplier<T> - with nothing as input, return a T [T get()]
BinaryOperator<T> - take two T's as input, return one T as output, useful for "reduce"
operations [T apply(T t1,T t2)]
IntConsumer - take an int as input, perform some action and don't return anything
[void accept(Int i)]
IntUnaryOperator - an operation on a single int-valued operand that produces an int-valued
result [int applyAsInt(int i)] 19
21. A bit of Lambda Calculus!!!
The λ-calculus is an elegant notation for working with applications of functions to
arguments.
In λ-calculus, the idea is the same: we create a function by using λ to specify which
arguments a function takes in, then we give an expression for the function’s return
value.
λ-calculus treats functions "anonymously", without giving them explicit names.
λ-calculus only uses functions of a single input. An ordinary function that requires
two inputs, for instance the function, can be reworked into an equivalent function
that accepts a single input, and as output returns another function, that in turn
accepts a single input.
21
22. Lambda Expressions
Lambda Expression is thought to be one of the biggest features of
Java 8 through which we can visualize functional programming in the
Java object oriented world.
It’s a shorthand that allows you to write a method in the same place
where it is going to be used.
Useful in places where a method is being used only once, and the
method definition is short. It saves the effort of declaring and writing
a separate method to the containing class
One of the major benefits of functional interface is the possibility to
use lambda expressions to instantiate them.
22
23. Anonymous classes to Lambda Expression
Remove below things in order:
new keyword new,
class name and it’s parentheses Comparator,
class opening and closing braces { };,
@Override annotation (if have any),
remove method declaration (leave argument parentheses (int arg1, int arg2)) public int compare
removing method opening { and closing braces } is not necessary, however, if there is single line of code in
it then it is advisable to remove them.
add -> between parentheses () and execution code inside { }
23
25. List<Person> people = loadPeople();
Collections.sort(people, new Comparator<Person>() {
@Override
public int compare(Person p1, Person p2){
return p1.getName().compareTo(p2.getName());
}
});
25
26. List<Person> people = loadPeople();
Collections.sort(people, new Comparator<Person>() {
@Override
public int compare(Person p1, Person p2){
return p1.getName().compareTo(p2.getName());
}
} );
26
27. List<Person> people = loadPeople();
Collections.sort(people, new Comparator<Person>() {
@Override
public int compare(Person p1, Person p2){
return p1.getName().compareTo(p2.getName());
}
} );
27
28. List<Person> people = loadPeople();
Collections.sort(people,
(Person p1, Person p2) ---> p1.getName().compareTo(p2.getName()));
28
29. List<Person> people = loadPeople();
Collections.sort(people,
(Person p1, Person p2) ---> p1.getName().compareTo(p2.getName()));
29
30. List<Person> people = loadPeople();
Collections.sort(people,
(p1,p2) ---> p1.getName().compareTo(p2.getName()));
30
31. List<Person> people = loadPeople();
Collections.sort(people, (p1,p2) ---> p1.getName().compareTo(p2.getName()));
Best Practices:
Make use of parameter type inference
Only specify the types when compiler needs it
Prefer expression lambda over block ones and if required create a separate method.
Avoid using parameter brackets for single argument methods.
31
35. Anonymous Class vs Lambda Expression
An anonymous class object creates a separate class
file after compilation which increases the size jar
while after compilation Lambda expression
becomes invokedynamic which dynamic language
implementation.
We can use this keyword to represent the current
class in lambda expression while in the case of
anonymous class this keyword represents that
particular anonymous class.
In the case of Lambda expression, we need to
provide the function body only while in the case of
anonymous class we need to write the redundant
class definition.
35
36. Function<T, R> - take a T as input, return an R as ouput
(x) --> Integer.parseInt(x);
Predicate<T> - take a T as input, return a boolean as output
(x) --> x%2==0;
Consumer<T> - take a T as input, perform some action and don't return anything
(x) -> System.out.println(x.toLowerCase());
Supplier<T> - with nothing as input, return a T.
() --> “Sample String”;
BinaryOperator<T> - take two T's as input, return one T as output
(x, y) --> x + y;
IntConsumer - take an int as input, perform some action and don't return anything
(x) --> System.out.println(x);
IntUnaryOperator - an operation on a single int-valued operand that produces an INT
(x) --> x * x;
36
37. Streams API
Sounds similar to InputStream and OutputStream from Java I/O. But Java 8 streams
are a completely different thing.
A java.util.Stream represents a sequence of elements on which one or more operations
can be performed.
Stream operations are either intermediate or terminal.
Intermediate operations return a stream so we can chain multiple intermediate
operations without using semicolons. Such a chain of stream operations is also
known as operation pipeline.
Terminal operations are either void or return a non-stream result.
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38. Not a data structure.
Streams have no storage;
A stream is something like an iterator. The
values "flow past" (analogy to a stream of water)
and then they're gone.
A stream can only be traversed once, then it's
used up.
Designed for lambdas. All stream operations
take lambdas as arguments
Parallelizable. If a stream is designated as
parallel all operations on it will automatically be
done in parallel without explicit use of threads.
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44. Collection is a data structure. Based on the problem you decide which collection to be used
like ArrayList, LinekedList (Considering time and space complexity) . Where as Stream is just
a processing kind of tool, which makes your life easy.
Collection can be considered as in-memory data structure, where we can add , remove
element. Where as in Stream you can perform two kind of operation:
a. Intermediate operation : Filter, map ,sort,limit on the result set
b. Terminal operation : forEach ,collect the result set to a collection.
With stream we can't add or remove elements.
Stream is kind of iterator, you can traverse collection through stream. Note, you can traverse
stream only once
While collections have a finite size, streams need not. Short-circuiting operations such as
limit(n) or findFirst() can allow computations on infinite streams to complete in finite time.
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45. Parallel Streams
Streams can be executed in parallel to increase
runtime performance on large amount of input
elements.
Parallel streams use a common ForkJoinPool
available via the static ForkJoinPool.commonPool()
method. The size of the underlying thread-pool uses
up to five threads - depending on the amount of
available physical CPU cores:
Collections support the method parallelStream() to
create a parallel stream of elements. Alternatively
you can call the intermediate method parallel() on
a given stream to convert a sequential stream to a
parallel counterpart.
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48. The parallel stream utilizes all available threads
from the common ForkJoinPool for executing the
stream operations. The output may differ in
consecutive runs because the behavior which
particular thread is actually used is non-
deterministic.
48
51. filter
Filter accepts a predicate to filter all elements of the stream. This operation is
intermediate which enables us to call another stream operation (forEach) on the
result.
stringCollection
.stream()
.filter((s) -> s.startsWith("a"))
.forEach(System.out::println);
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52. sorted
Sorted is an intermediate operation which returns a sorted view of the stream. The
elements are sorted in natural order unless you pass a custom Comparator.
stringCollection
.stream()
.sorted()
.filter((s) -> s.startsWith("a"))
.forEach(System.out::println);
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53. map
The intermediate operation map converts each element into another object via the
given function. But you can also use map to transform each object into another type.
The generic type of the resulting stream depends on the generic type of the function
you pass to map
stringCollection
.stream()
.map(String::toUpperCase)
.sorted((a, b) -> b.compareTo(a))
.forEach(System.out::println);
53
54. count
Count is a terminal operation returning the number of elements in the stream as a
long.
long startsWithB =
stringCollection
.stream()
.filter((s) -> s.startsWith("b"))
.count();
54
55. collect
Collect is an extremely useful terminal operation to transform the elements of the
stream into a different kind of result, e.g. a List, Set or Map.
Collect accepts a Collector which consists of four different operations: a supplier, an
accumulator, a combiner and a finisher. This sounds super complicated at first, but the
good part is Java 8 supports various built-in collectors via the Collectors class.
List<Person> filtered =
persons
.stream()
.filter(p -> p.name.startsWith("P"))
.collect(Collectors.toList());
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56. count
Map<Integer, List<Person>> personsByAge = persons
.stream()
.collect(Collectors.groupingBy(p -> p.age));
personsByAge
.forEach((age, p) -> System.out.format("age %s: %sn", age, p));
create aggregations on the elements of the stream, e.g. determining the average age of
all persons:
Double averageAge = persons
.stream()
.collect(Collectors.averagingInt(p -> p.age));
56
57. count
n order to transform the stream elements into a map, we have to specify how both the
keys and the values should be mapped. Keep in mind that the mapped keys must be
unique, otherwise an IllegalStateException is thrown. You can optionally pass a merge
function as an additional parameter to bypass the exception:
Map<Integer, String> map = persons
.stream()
.collect(Collectors.toMap(
p -> p.age,
p -> p.name,
(name1, name2) -> name1 + ";" + name2));
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58. reduce
The reduce operation combines all elements of the stream into a single result. Java 8
supports two different kind of reduce methods.
1. Accepts a BinaryOperator accumulator function/reduces a stream of elements to
exactly one element of the stream. determine the oldest person:
persons
.stream()
.reduce((p1, p2) -> p1.age > p2.age ? p1 : p2)
.ifPresent(System.out::println);
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59. reduce
2. Accepts both an identity value and a BinaryOperator accumulator.
construct a new Person with the aggregated names and ages from all other persons in
the stream:
Person result =
persons
.stream()
.reduce(new Person("", 0), (p1, p2) -> {
p1.age += p2.age;
p1.name += p2.name;
return p1;
});
59
60. Most stream operations accept some kind of lambda expression parameter, a
functional interface specifying the exact behavior of the operation.Most of those
operations must be both non-interfering and stateless.
A function is non-interfering when it does not modify the underlying data source of
the stream.
A function is stateless when the execution of the operation is deterministic.
60
61. Optional
New class 'Optional' added to Java 8
Optional is a simple container for a value which may be null
or non-null. Think of a method which may return a non-null
result but sometimes return nothing. Instead of returning null
an Optional can be returned in Java 8.
Simple concept - two states
• present, with a value - Optional.of(foo)
• empty - Optional.empty()
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65. Best Practices:
Variable of type Optional must NEVER be null.
Assign empty variable as Optional.empty();
Optional is designed as a return type and not an input type.
Prefer functional methods like orElse()
Using isPresent() a lot is misusing the feature.
65
66. Date APIs
Date & Time API is a new introduction in Java 8
Designed to overcome all the flaws in the legacy
date time implementations.
66
67. Why new Date API?
Java Date Time classes are not defined consistently, we have Date Class in both java.util as
well as java.sql packages. Again formatting and parsing classes are defined in java.text package.
java.util.Date contains both date and time, whereas java.sql.Date contains only date. Also both
the classes have same name, that is a very bad design itself.
There are no clearly defined classes for time, timestamp, formatting and parsing.
All the Date classes are mutable, so they are not thread safe. It’s one of the biggest problem
with Java Date and Calendar classes.
Date class have no timezone support. So java.util.Calendar and java.util.TimeZone classes were
introduced, but they also have all the problems listed above.
67
69. Immutability: All the classes in the new Date Time API are immutable and
good for multithreaded environments.
Separation of Concerns: The new API separates clearly between human
readable date time and machine time (unix timestamp). It defines separate
classes for Date, Time, DateTime, Timestamp, Timezone etc.
Clarity: The methods are clearly defined and perform the same action in all
the classes. For example, to get the current instance we have now() method.
There are format() and parse() methods defined in all these classes rather
than having a separate class for them. All the classes use Factory Pattern and
Strategy Pattern for better handling. Once you have used the methods in one
of the class, working with other classes won’t be hard.
Utility operations: All the new Date Time API classes comes with methods
to perform common tasks, such as plus, minus, format, parsing, getting
separate part in date/time etc.
69
70. The java.time.LocalDate class represents a date without time or timezones; the
java.time.LocalTime class represents time without dates and timezones; the
java.time.LocalDateTime class represents both date and time without time zones.
The java.time.Instant class represents a Unix timestamp. Instants can be used to
create legacy java.util.Date objects
The java.time.Period is used to measure the amount of time in terms of years,
months, and days.
The java.time.Duration class represents time in terms of hours, minutes,seconds,
and fraction of seconds.
ZoneId identifies a time zone; ZoneOffset represents time zone offset from
UTC/Greenwich.
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71. ZonedDateTime provides support for all three aspects: date, time, and timezone.
The java.time.format.DateTimeFormatter class provides support for reading or
printing date and time values in different formats.
The DateTimeFormatter class provides predefined constants (such as ISO_DATE
and ISO_TIME ) for formatting date and time values.
The Java 8 date and time API differentiates how humans and computers use date-
and time-related information.
71
74. Repeatable Annotations
Prior to Java8, it was forbidden to declare more than one annotation of the same type
to the same location of a code.
Annotations in Java 8 are repeatable.
Java 8 enables us to use multiple annotations of the same type by declaring the
annotation @Repeatable
74
75. Prior to Java8, to have a repeated annotation, will have to group them in a container
annotation
With Java8 repeating annotations, it gives us the flexibility to write the same thing
without any container annotation
Though the container annotation was not used here, the Java compiler this time
around takes responsibility for wrapping the two annotations into a container.
75
76. String Joiners
Java 8 added a new class called StringJoiner.and as the name suggests we can use this
class to join strings.
String joined = String.join("/", "2014", "10", "28" ); // "2014/10/28"
Intention is to abstract away the choice of seperator from the act of adding entries.
StringJoiner is very useful, when it is needed to join Strings in a Stream.
String joinedString = Stream.of("Foo","Bar","Baz").collect(Collectors.joining(":", "[", "]"));
System.out.println(joinedString);
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Java 7 is now end of life—making Java 8 the only Oracle-supported option until Java 9. However, since organizations value stability over trendiness, many of us are still working with Java 7, or even 6.
http://cr.openjdk.java.net/~briangoetz/lambda/Defender%20Methods%20v4.pdf
Why can't default methods override equals, hashCode, and toString?
Since the ValidationUtils will need to have the validation logic very specific to the business requirement for SimpleInterface the best place to define it can be in the interface itself and we can totally get rid of the ValidationUtils class.
Abstract is object oriented. It offers the basic data an 'object' should have and/or functions it should be able to do. It is concerned with the object's basic characteristics: what it has and what it can do. Hence objects which inherit from the same abstract class share the basic characteristics (generalization). It reflects "is a" relation with concrete classes
Interface is functionality oriented. It defines functionalities an object should have. Regardless what object it is, as long as it can do these functionalities, which are defined in the interface, it's fine. It ignores everything else. An object/class can contain several (groups of) functionalities; hence it is possible for a class to implement multiple interfaces. It provides "has a" capability for classes.
Simplification1:
the function
sqsum(x,y) = x*x + y*y
can be rewritten in anonymous form as
(x,y) -> x*x +y*y;
Simplification2:
sqsum(x,y) = x*x + y*y
can be reworked into
x -> (y->x*x + y*y)
A lambda expression can have zero, one or more parameters.
The type of the parameters can be explicitly declared or it can be inferred from the context. e.g. (int a) is same as just (a)
Parameters are enclosed in parentheses and separated by commas. e.g. (a, b) or (int a, int b) or (String a, int b, float c)
Empty parentheses are used to represent an empty set of parameters. e.g. () -> 42
When there is a single parameter, if its type is inferred, it is not mandatory to use parentheses. e.g. a -> return a*a
The body of the lambda expressions can contain zero, one or more statements.
If body of lambda expression has single statement curly brackets are not mandatory and the return type of the anonymous function is the same as that of the body expression.
When there is more than one statement in body than these must be enclosed in curly brackets (a code block) and the return type of the anonymous function is the same as the type of the value returned within the code block, or void if nothing is returned.
Lambda Expressions allows us to code in functional style so it provides all benefits of functional style as well as we can see Lambda Expressions lets developers
Simply understand the code.
Simplify and shorten their code.
Making it more readable and maintainable.
Remove more verbose class declarations.
ForkJoinPool commonPool = ForkJoinPool.commonPool();
System.out.println(commonPool.getParallelism());
This value can be decreased or increased by setting the following JVM parameter:
-Djava.util.concurrent.ForkJoinPool.common.parallelism=5
Keep in mind that sorted does only create a sorted view of the stream without manipulating the ordering of the backed collection. The ordering of stringCollection is untouched: