Naming conventions for Java methods that return boolean

Question

I like using question mark at the end of method function names in other languages  Java doesn t let me do this  As a workaround how else can I name boolean returning methods in Java  Using an is  has  should  can in the front of a method sound okay for some cases  Is there a better way to name such methods   For e g  createFreshSnapshot

User · Answer

I want to post this link as it may help further for peeps checking this answer and looking for more java style convention

Java Programming Style Guidelines

Item "2.13 is prefix should be used for boolean variables and methods." is specifically relevant and suggests the is prefix.

The style guide goes on to suggest:

There are a few alternatives to the is prefix that fits better in some situations. These are has, can and should prefixes:

boolean hasLicense();
boolean canEvaluate();
boolean shouldAbort = false;

If you follow the Guidelines I believe the appropriate method would be named:

shouldCreateFreshSnapshot()

User · Answer

If you wish your class to be compatible with the Java Beans specification  so that tools utilizing reflection  e g  JavaBuilders  JGoodies Binding  can recognize boolean getters  either use getXXXX   or isXXXX   as a method name  From the Java Beans spec   8 3 2 Boolean properties In addition  for boolean properties  we allow a getter method to match the pattern  public boolean is lt PropertyName gt     This    is lt PropertyName gt     method may be provided instead of a    get lt PropertyName gt     method  or it may be provided in addition to a    get lt PropertyName gt     method  In either case  if the    is lt PropertyName gt     method is present for a boolean property then we will use the    is lt PropertyName gt     method to read the property value  An example boolean property might be  public boolean isMarsupial    public void setMarsupial boolean m

User · Answer

The convention is to ask a question in the name   Here are a few examples that can be found in the JDK   isEmpty    hasChildren     That way  the names are read like they would have a question mark on the end      Is the Collection empty    Does this Node have children    And  then  true means yes  and false means no   Or  you could read it like an assertion      The Collection is empty    The node has children   Note  Sometimes you may want to name a method something like createFreshSnapshot    Without the question mark  the name implies that the method should be creating a snapshot  instead of checking to see if one is required     In this case you should rethink what you are actually asking   Something like isSnapshotExpired is a much better name  and conveys what the method will tell you when it is called  Following a pattern like this can also help keep more of your functions pure and without side effects   If you do a Google Search for isEmpty   in the Java API  you get lots of results

User · Answer

is is the one I ve come across more than any other  Whatever makes sense in the current situation is the best option though

User · Answer

I want to point a different view on this general naming convention  e g   see java util Set  boolean  add  E  e  where the rationale is  do some processing then report whether it succeeded or not  While the return is indeed a boolean the method s name should point the processing to complete instead of the result type  boolean for this example   Your createFreshSnapshot example seems for me more related to this point of view because seems to mean this  create a fresh-snapshot then report whether the create-operation succeeded  Considering this reasoning the name createFreshSnapshot seems to be the best one for your situation

User · Answer

Standard is use is or has as a prefix  For example isValid  hasChildren

User · Answer

For methods which may fail  that is you specify boolean as return type  I would use the prefix try   if  tryCreateFreshSnapshot                   For all other cases use prefixes like is   has   was   can   allows

[java] Naming conventions for Java methods that return boolean

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