If you are looking for a radio-controlled helicopter, the most difficult question to answer is: “what should I buy?”
Bear in mind that if you skip to answer this question, then you might be ending up with a one time flying experience. In other words, after you have bought and first flown your radio-controlled helicopter, you might not be able to fly it again.
So here are the things you should know in order to get you end up getting the right radio-controlled helicopter for you.
If you have yet to fly an rc helicopter, then you should settle for kinds that are easy to fly. What you should be looking for is an electric radio-controlled helicopter. In this way, you eliminate the risk of crashing down your newly purchased helicopter to the ground. This is a great starting point to those who would like to take rc helicopter flying a hobby. Electric radio-controlled helicopter is also quiet. So if you are considerate enough to give your neighbors some peace, then this one is for you
Rc helicopter, whether it is electric or gas, comes in different sizes and identifying what is the size you need is important. Here you can trim down your choices into gas, electric, mini, micro, and toy.
Gas rc helicopter is relatively larger than other type of rc helicopters while electric rc helicopter can be categorized into 3 sizes- that is, electric, mini and micro.
If you are planning to fly your rc helicopter on open spaces, then the electric rc helicopter is your ideal size. On the other hand, if you only prefer indoor flying, then you can either choose the mini or the micro.
Crashes can come anytime so make sure that when you purchase a model, you also purchase parts. Used parts are abundant but they are less reliable so you have to determine if there are new parts available for the type of rc helicopter you are buying.
The price of rc helicopter depends on the size and components used. Make sure you have set your budget so that you can limit your selection that would make buying easier.
They tell the developer immediately where he is wrong and also they will defend the code against unwanted changes and bugs in the future, like many small powerful soldiers.
Acceptance test are also very important because they are defined by or with the product owners and they contain the actual functionality expected from the business.
Integration tests are less important, but still important. They are there to test “happy paths” and make sure communication between components is fine. Communication NOT functionality!
They are difficult to maintain, to mock, to extends. Slow to run. Hard to understand. They corrupt code coverage. They give big false positive thinking.
I know what you are thinking.....the maiden flight of the Ariane 5 launcher failure, still I'm not a big fan of these.
Performance and stress tests are important, as you can imagine they test your software under extreme circumstances. They tell you if you met the product owner expectations in terms of SLA and Throughput, and they tell you also if you introduced some kind of nasty bottleneck before going to production.
And finally manual UAT tests, that are normally run by product owners to verify that everything is cool and ready to make the business rich.
CompletableFuture can be a complex concept if taken by itself, so I will use a simple example here to show for one business requirement, how to use it, when to use it and what is the difference comparing to parallelStream.
Build a list of promotion Strings. For each one you need to send an email to all the customers with the promotion. You also need to send an email to the Boss saying that promotions have been applied today.
The boss email and the customers emails are independent to each others and should not wait on either completion.
For each promotion we add the discount percentage. Then we add the day of when the discount is valid. Lastly we send the emails to all the customers. At the end we send the email to the Boss.
We can improve the speed of the algorithm parallelizing the process of sending emails to the customers using parallelStream :
But we still have a requirement to fulfill, customers and Boss don't want to wait on each other to receive their emails.
Everything is asynchronous here and CompletableFuture[] futures holds the composed completableFutures.
When the jvm rich the line sendEmailToTheBoss("Today discount was 30%"); , some of the customers email will be already sent and some are still to be sent, but we don't care to wait, we just want to acknowledge our Boss that promotions were generated.
The last line CompletableFuture.allOf(futures).join(); is because before leaving this method we want to wait for all the emails to be sent to the customers.
These are two examples on how to implement a Strategy pattern design using Java 8 functional style together with Cyclops pattern matching and Hamcrest libraries.
PrintDependingOnInput method is a strategy that will System.println some message based on the log passed.
I was wondering how the hell can Optional remove the need to check for null? At some point I will need to use optional.isPresent() before using whatever is inside. So what's the point to replace == null with isPresent()?
The main concept to keep in mind is that Optional is a monad and as a monad contains map(), flatmap(), filter() and other methods that can be used directly against the optional instance.
Here, with the following simple code, I hope I will clarify a bit more the power of java.util.Optional.
In this example we have a list of logs and we want to apply 3 different operations based on the the type of log (INFO, ERROR, WARN).
Cyclops is another promising open source library from John McClean in AOL, that aims to extends and simplify Java 8 functionality.
Traditionally, we could have manage exceptions surrounding the loadFiles() method with try and catch and handle each exception within a catch statement.
When you enter in the office, before sitting on your desk, smile and say good morning to the team. Yes, E V E R Y day.
You may be always right, but who cares?! Other people need to learn to fail and take responsibilities.
Do code reviews without sounding the king of the programming universe. Explain in a calm and friendly tone whatever you want to say.
Memoization is not a grammar error, memoization is an optimization technique used primarily to speed up computer programs by storing the results of expensive function calls and returning the cached result when the same inputs occur again.
We have a java function called "hereThePizzaGiveMeTheId" where you pass a String representing a pizza name and it will return the correspondent id retrieved from the DB.
Fantastic, but I don't want to run that function every time, if I already know the result based on the pizza name.
First we create a generic method that wraps a function into another function that will behave the same as the input one, but will check if the result is already computed :
Because you are a good and careful developer you want to keep things immutable as much as possible. So adding a new element to an immutable collections will mean that you have to create a new immutable collection that contains all the elements of the original collections plus the new element.
You can create immutable collections using the guava library and also using the recent pCollection library.
In the following example, we will build 2 immutable lists, one immutable from guava and one persistent from pCollection.
Because you have no total control : objects can be passed anywhere and can arrive from anywhere in the code. If they are mutable, then any object can modify their state. Different threads can access the same model object and modify/read its state creating many problems difficult to handle.