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This is more of a conceptual question than technical pertaining to Java. I've noticed lately programmers tend to avoid creating classes to pass data around and simply move it using JSONObject if available or a basic HashMap. A lot of new interviewees choose to use what I call a JavaScript method of coding. So instead of creating class called Address, they would store it all in JSONObject/HashMap and pass it around as Object later casting to appropriate type. Also I notice a lot of
try { ... }
finally { return str; }
structured methods.
Is this something normal and accepted these days? To me, it just goes against everything I was thought in school. I mean, no generalization, no encapsulation, etc... And when asked, they claim JSONObject is encapsulation. Well, not disagreeing, but just not something expected.
The task is always being done in the end, but the way its done is disturbing to me. This kind of practice produces a lot of loose structures with a lot of potential errors if programmers are not careful. Wasn't java generics created to avoid exactly that?
Feel free to move this question to other exchange, but I'd really like to hear some opinions from seasoned folks.
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Currently my program is filled with many ugly references that often make field or method access look like this: weakReference1.get().weakReference2.get().field1.getSomeCustomObject().field2. I want to move to shorter and faster strong references like field1.field2. But my program design is such that I will also have to go for an ArrayList element-by-element search (in a for-loop) instead of accessing a WeakHashMap by get() method.
Thus, I'd like to understand, can moving to simpler references compensate for rejecting HashMap performance wise. Herewith I presume that WeakHashMap.get() is much faster than a loop-search of ArrayList.
Can someone, please, give me a rough estimate? Or maybe there's even an appropriate comparison table like this one. I'd appreciate that.
Thank you.
Currently my program is filled with many ugly references that often make field or method access look like this:
weakReference1.get().weakReference2.get().field1.getSomeCustomObject().field2
Given that the objects involved are not Data Transfer Objects
this is a violation of the law of Demeter aka Don't talk to Strangers / Tell, don't ask!
Following this LoD principle you should move the operations working with the data in field2 to a new method in the class SomeCustomObject.
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I was using this code to create some sort of a universal changer class:
//constructor method
public Change(Object affdObj, String affdField, float modifier) {
obj = affdObj;
//...
affectedField = affdObj.getClass().getField(affdField);
//...
affectedField.setFloat(obj, affectedField.getFloat(obj) + modifier);
}
But then I was advised to avoid reflection whenever possible since it's very slow. I was suggested to pay attention to interfaces. Unfortunately I can't see how to fit interfaces to my code.
Hence my question: if one needs to access a field which name he doesn't know in advance are there any options other than using reflection?
PS
Thank you for replies, guys.
And since my question is put on hold as primarily opinion-based, I consider this to be the answer to my question, i.e. there is no other way to achieve my goal which is better than mine in every aspect. In other words, I conclude that my approach is OK. Thank you.
First of all, reflection is not slow (anymore) and is widely used (Spring uses it, Hibernate uses it, etc.). So, you use it with confidence if your only concern is speed.
Regarding other ways to do what you want, since you provide the field name as as a string and identify it like that, you cannot do it with interfaces.
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I recently started a project in Java, that contains a class called System. This class (Luckily) contains methods for output management, so in the rare cases where I need to use the System. methods (Or the System object in general) I just reference it as java.lang.System.. I believe that this could be looked down upon, as System could be looked at as a reserved name. I currently am in the beginning stages of this program, and could change it accordingly quickly, as there are little calls to the class itself.
While it's not illegal, you don't want to do this. If I were the next person working on your code, the first thing I would do is try to remove "java.lang" from "java.lang.System" and then get miffed when it wouldn't compile.
The idea is to go toward brevity and only write what you need to write, while making sense of it all for the next person. It's more an art than a science.
You could always name it something like ProjectnamehereSystem or OutputManager or something to that effect.
I would not create something so similarly named as an important class. While everything is easy to edit, you may be able to keep up with all the changes you are making.
But when the project evolves things will get messy and complex. I would suggest naming it something else that can be easily distinguished.
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My project classes are quickly approaching large numbers of lines into the thousands. Is it good programming practice to divide the classes Into smaller classes even if they do the same thing? After all I'd hate to create communication caller functions for the same object.
It is a good programming practice to split up your code so you (and others) don't get lost.
Split it into methods/functions/procedures, classes and packages by meaning, not by size alone.
If several classes do the same thing, have you thought about using inheritance? Don't duplicate code, it makes maintenance harder (and is a waste).
For Java, interfaces and abstract classes can also improve legibility and structure of your code; use with moderation. Many Java IDEs come with handy "refactoring" functionalities which allow you to restructure your code easier and cleaner than copy/paste would be.
( Possibly related topic: "how do you organize your programming work" how do you organize your programming work )
As a rule, each class should have one responsibility that you can clearly state. If you can't state a single purpose for a class, or the narrowest purpose you can define is nebulous and vague, it's time to refactor.
Of course there are exceptions to every rule, and some classes with a lot of utility methods (like String) will be very large. But I generally take a hard look at the purpose of a class when it grows past about 300 lines. (For the second time - I do it the first time before the class grows past 0 lines.)
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We are learning about both of these things in Java class right now. I believe I understand the basic aspects of both, but not sure about how Casting ends up limiting Algorithm Reuse. Our teacher said we need to know this for the test next week. Can anyone explain this?
If you cast you are limiting your algorithm to only work with one Class (or it's children). If you were instead to use an Interface you would be able to accept a greater variety of Objects that themselves implement that Interface. Much more flexible.
Here is a related SO question: Explaining Interfaces to Students
When you use casting in your code, you must know the exact type that you cast to (during the code write phase). Hence your code can't be reused in the future with different types. Always remember to program to interface instead of to specific type.