java – I still don’t fully understand getters & setters


I’m still really new to learning to program. Just learning the syntax for a few programming languages at the moment.

The courses I viewed for C# and Java touched only very briefly on getters & setters and it still didn’t make an awful lot of sense to me. So I researched them further and found that the whole subject of getters & setters is a lot more debated than I could believe. For every argument & example both for and against getters & setters there was a counter argument, saying that it was wrong, the code was a bad example etc. and I still didn’t know who to agree with or even fully grasp the jargon behind it.

So I’m really not sure what to go for at the moment. So I’m going to post my take on what getters & setters really are given what I’ve read and if there’s anything I’ve got wrong then please tell me. Then I have a few more questions that I haven’t found any answers for anywhere.

My take on getters & setters

FOR:

  • Getters and setters are methods declared within a class and applied to fields within said class, and control what other classes can access and modify these fields.

  • They’re used on fields which need to be accessed from outside their class, but at the same time cannot let anything have access other than what needs access.

  • When programmers talk about “if you make a field public then ANYONE can have access to them” by anyone they’re not necessarily talking about hackers or the user of your finished program. They’re talking about any other programmers who are working on the same program (or yourself) creating something which accidentally creates side effects which modify that class. Then you not being able to work out what is causing that change.

  • As well as controlling access they can do other things such as validate any input to the field before it is added (Mike Dane aka Giraffeacademy has used the example several times that a movie can only have 3 age ratings, so adding into the setter a method which checks the rating of a movie before it is added is a good side effect of a setter). In the same example, it can also improve the maintainability of your program, for example if a fourth rating is added, you can modify any objects where the new rating applies to just by adding it to the setter, rather than going through each movie individually.

AGAINST

  • Many programmers nowadays are strongly against the use of getters and setters. They argue that it ruins the encapsulation of your objects and makes code noisy and unreadable. Also that they encourage programmers to think of objects as data structures.

  • I’ve seen some arguments that they are now somewhat obsolete as some programming languages such as Python, which doesn’t need to use getters & setters. Also some IDE’s make it easy to see where side effects are taking place.

  • The main argument I’ve seen against them is that they’re just poor design. Code and classes should be clean and organised in a way that fields are only accessed outside the class when it absolutely needs to be, and getters and setters should only be used as a last resort.

  • An idea I saw recently is that you should start off making every field you create private. Then find everything which needs to be accessed outside the class and if there’s no other way around it, add a getter and/or setter to it.

The final, neutral argument I’ve seen is that you shouldn’t be adding things to your code that you don’t understand or don’t know if you’re going to need or not. That I absolutely agree with. But obviously I need to know if they’re going to be useful to me or not when I actually create something.

So if I’ve got anything wrong then please let me know, and I still have a few questions:

  • What parts of your program would you actually use getters and setters on? The examples I’ve seen online use classes such as ‘Dog/Ball’ and ‘Person’ which really aren’t much use to me. I’m thinking you would use them if you had a class for ‘Accounts’ and a different class for ‘Settings’.. the settings class would need to access the Account’s user name if the username requested to change it.. right?

  • Going with that example, if getters and setters are created to prevent someone from being able to change a variable through a side effect, what kind of code could actually change a user’s name as a side effect accidentally? Surely the only kind of areas in your program that could modify an accounts username are setUsername, displayUsername and changeUsername, and nothing else would ever need to go near those variables.

  • Given the debate I’ve found surrounding getters & setters why do courses and tutorials touch so briefly on them only just teaching you the syntax for them, and not arguing the cases for and against or even providing actual real world examples? (See note before about dog/ball). Are they too biased of an opinion? Or am I just looking into one topic way too much?

As I said I’m still so new to programming, so I’m probably either too inexperienced or thinking about it way too much. I just want to be absolutely clear on what I’m adding/not adding to my programs before I release them to the world.

Any help much appreciated. Have a good day.