Using underscores in Java variables and method names

Question

Even nowadays I often see underscores in Java variables and methods  an example are member variables  like  m count  or   count    As far as I remember  to use underscores in these cases is called bad style by Sun   The only place they should be used is in constants  like in  public final static int IS OKAY   1     because constants should be all upper case and not camel case  Here  the underscore should make the code more readable   Do you think using underscores in Java is bad style  If so  or not   why

User · Accepted Answer

If you have no code using it now  I d suggest continuing that   If your codebase uses it  continue that   The biggest thing about coding style is consistency   If you have nothing to be consistent with  then the language vendor s recommendations are likely a good place to start

User · Answer

Bad style  is very subjective  If a certain conventions works for you and your team  I think that will qualify a bad good style   To answer your question  I use a leading underscore to mark private variables  I find it clear and I can scan through code fast and find out what s going on    I almost never use  this  though  except to prevent a name clash

User · Answer

It s nice to have something to distinguish private vs  public variables  but I don t like     in general coding  If I can help it in new code  I avoid their use

User · Answer

It s a blend of coding styles  One school of thought is to preface private members with an underscore to distinguish them   setBar  int bar        bar   bar      instead of   setBar  int bar       this bar   bar      Others will use underscores to indicate a temp local variable that will go out of scope at the end of the method call   I find this pretty useless - a good method shouldn t be that long  and the declaration is RIGHT THERE  so I know it goes out of scope  Edit  God forbid a programmer from this school and a programmer from the memberData school collaborate  It would be hell   Sometimes  generated code will preface variables with   or      The idea being that no human would ever do this  so it s safe

User · Answer

sunDoesNotRecommendUnderscoresBecauseJavaVariableAndFunctionNamesTendToBeLongEnoughAsItIs     as others have said consistency is the important thing here so chose whatever you think is more readable

User · Answer

The reason people do it  in my experience  is to differentiate between member variables and function parameters   In Java you can have a class like this   public class TestClass     int var1     public void func1 int var1         System out println  Which one is it       var1          If you made the member variable  var1 or m var1  you wouldn t have the ambiguity in the function   So it s a style  and I wouldn t call it bad

User · Answer

There is a reason why using underscores was considered being bad style in the old days  When a runtime compiler was something unaffordable and monitors came with astonishing 320x240 pixel resolution it was often not easy to differentiate between  name and   name

User · Answer

it s just your own style nothing a bad style code and nothing a good style code just difference our code with the others

User · Answer

I don t think using   or m  to indicate member variables is bad in Java or any other language   It my opinion it improves readability of your code because it allows you to look at a snippet and quickly identify out all of the member variables from locals     You can also achieve this by forcing users to prepend instance variables with  this  but I find this slighly draconian   In many ways it violates DRY because it s an instance variable  why qualify it twice     My own personal style is to use m  instead of     The reason being that there are also global and static variables   The advantage to m    is it distinguishes a variables scope   So you can t reuse   for global or static and instead I choose g  and s  respectively

User · Answer

using  m   or     in the front of a variable makes it easier to spot member variables in methods throughout an object    As a side benefit typing  m   or     will make intellsense pop them up first

User · Answer

I happen to like leading underscores for  private  instance variables  it seems easier to read and distinguish Of course this thing can get you into trouble with edge cases  e g  public instance variables  not common  I know  - either way you name them you re arguably breaking your naming convention  private int  my int   public int myInt    my int       -as much as I like the  style of this and think it s readable I find it s arguably more trouble than it s worth  as it s uncommon and it s likely not to match anything else in the codebase you re using    -automated code generation  e g  eclipse s generate getters  setters  aren t likely to understand this so you ll have to fix it by hand or muck with eclipse enough to get it to recognize    Ultimately  you re going against the rest of the  java  world s prefs and are likely to have some annoyances from that  And as previous posters have mentioned  consistency in the codebase trumps all of the above issues

User · Answer

I think any style that breaks a language s own style guidelines  without due reason  is ugly and therefore  bad    No doubt the code you ve seen was written by someone who used to work on a language where underscores were acceptable   Some people just cannot adapt to new coding styles

User · Answer

Rules    Do what the code you are editing does If  1 doesn t apply  use camelCase  no underscores

User · Answer

it s just your own style nothing a bad style code and nothing a good style code just difference our code with the others

User · Answer

Here s a link to Sun s recommendations for Java  Not that you have to use these or even that their library code follows all of them  but it s a good start if you re going from scratch   Tool like Eclipse have built in formatters and cleanup tools that can help you conform to these conventions  or others that you define    For me      are too hard to type

User · Answer

Personally  I think a language shouldn t make rules about coding style  It is a matter of preferences  usage  convenience  concept about readability  Now  a project must set coding rules  for consistency across listings  You might not agree with these rules  but you should stick to them if you want to contribute  or work in a team    At least  IDEs like Eclispe are agnostic  allowing to set rules like variable prefixes or suffixes  various styles of brace placement and space management  etc  So you can use it to reformat code along your guidelines   Note  I am among those keeping their old habits from C C    coding Java with m  prefixes for member variables  and s  for static ones   prefixing booleans with an initial b  using an initial uppercase letter for function names and aligning braces    The horror for Java fundamentalists   -  Funnily  that s the conventions used where I work    probably because the main initial developer comes from MFC world   -D

[java] Using underscores in Java variables and method names

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