Why is there no String Empty in Java

Question

I understand that every time I type the string literal     the same String object is referenced in the string pool   But why doesn t the String API include a public static final String Empty        so I could use references to String Empty   It would save on compile time  at the very least  since the compiler would know to reference the existing String  and not have to check if it had already been created for reuse  right  And personally I think a proliferation of string literals  especially tiny ones  in many cases is a  code smell    So was there a Grand Design Reason behind no String Empty  or did the language creators simply not share my views

User · Answer

Apache StringUtils addresses this problem too.

Failings of the other options:

isEmpty() - not null safe. If the string is null, throws an NPE
length() == 0 - again not null safe. Also does not take into account whitespace strings.
Comparison to EMPTY constant - May not be null safe. Whitespace problem

Granted StringUtils is another library to drag around, but it works very well and saves loads of time and hassle checking for nulls or gracefully handling NPEs.

User · Answer

All those    literals are the same object  Why make all that extra complexity  It s just longer to type and less clear  the cost to the compiler is minimal   Since Java s strings are immutable objects  there s never any need at all to distinguish between them except possibly as an efficiency thing  but with the empty string literal that s not a big deal   If you really want an EmptyString constant  make it yourself  But all it will do is encourage even more verbose code  there will never be any benefit to doing so

User · Answer

If you really want a String EMPTY constant  you can create an utility static final class named  Constants   for example  in your project  This class will maintain your constants  including the empty String     In the same idea  you can create ZERO  ONE int constants    that don t exist in the Integer class  but like I commented  it would be a pain to write and to read    for int i Constants ZERO             if myArray length  gt  Constants ONE            System out println  More than one element              Etc

User · Answer

String EMPTY is 12 characters  and    is two  and they would both be referencing exactly the same instance in memory at runtime  I m not entirely sure why String EMPTY would save on compile time  in fact I think it would be the latter   Especially considering Strings are immutable  it s not like you can first get an empty String  and perform some operations on it - best to use a StringBuilder  or StringBuffer if you want to be thread-safe  and turn that into a String   Update From your comment to the question      What inspired this is actually   TextBox setText        I believe it would be totally legitimate to provide a constant in your appropriate class   private static final String EMPTY STRING         And then reference it as in your code as  TextBox setText EMPTY STRING     As this way at least you are explicit that you want an empty String  rather than you forgot to fill in the String in your IDE or something similar

User · Answer

For those claiming    and String Empty are interchangeable or that    is better  you are very wrong   Each time you do something like myVariable       you are creating an instance of an object  If Java s String object had an EMPTY public constant  there would only be 1 instance of the object     E g  -  String EMPTY         Simply demonstrating  I realize this is invalid syntax  myVar0   String EMPTY  myVar1   String EMPTY  myVar2   String EMPTY  myVar3   String EMPTY  myVar4   String EMPTY  myVar5   String EMPTY  myVar6   String EMPTY  myVar7   String EMPTY  myVar8   String EMPTY  myVar9   String EMPTY    10  11 including String EMPTY  Pointers to 1 object  Or  -  myVar0       myVar1       myVar2       myVar3       myVar4       myVar5       myVar6       myVar7       myVar8       myVar9         10 pointers to 10 objects  This is inefficient and throughout a large application  can be significant   Perhaps the Java compiler or run-time is efficient enough to automatically point all instances of    to the same instance  but it might not and takes additional processing to make that determination

User · Answer

Seems like this is the obvious answer  String empty   org apache commons lang StringUtils EMPTY   Awesome because  quot empty initialization quot  code no longer has a  quot magic string quot  and uses a constant

User · Answer

If you want to compare with empty string without worrying about null values you can do the following   if     equals text     Ultimately you should do what what you believe is clearest   Most programmers assume    means empty string  not a string someone forgot to put anything into   If you think there is a performance advantage  you should test it   If you don t think its worth testing for yourself  its a good indication it really isn t worth it   It sounds like to you try to solve a problem which was solved when the language was designed more than 15 years ago

User · Answer

Use org apache commons lang StringUtils EMPTY

User · Answer

Don t just say  memory pool of strings is reused in the literal form  case closed   What compilers do under the hood is not the point here  The question is reasonable  specially given the number of up-votes it received   It s about the symmetry  without it APIs are harder to use for humans   Early Java SDKs notoriously ignored the rule and now it s kind of too late  Here are a few examples on top of my head  feel free to chip in your  favorite  example    BigDecimal ZERO  but no AbstractCollection EMPTY  String EMPTY Array length but List size   List add    Set add   but Map put    ByteBuffer put   and let s not forget StringBuilder append    Stack push

User · Answer

To add on to what Noel M stated  you can look at this question  and this answer shows that the constant is reused   http   forums java net jive message jspa messageID 17122     String constant are always  interned    so there is not really a need for such   constant   String s     String t     boolean b s  t     true

User · Answer

Late answer  but I think it adds something new to this topic   None of the previous answers has answered the original question  Some have attempted to justify the lack of a constant  while others have showed ways in which we can deal with the lack of the constant  But no one has provided a compelling justification for the benefit of the constant  so its lack is still not properly explained   A constant would be useful because it would prevent certain code errors from going unnoticed   Say that you have a large code base with hundreds of references to     Someone modifies one of these while scrolling through the code and changes it to      Such a change would have a high chance of going unnoticed into production  at which point it might cause some issue whose source will be tricky to detect   OTOH  a library constant named EMPTY  if subject to the same error  would generate a compiler error for something like EM PTY   Defining your own constant is still better  Someone could still alter its initialization by mistake  but because of its wide use  the impact of such an error would be much harder to go unnoticed than an error in a single use case   This is one of the general benefits that you get from using constants instead of literal values  People usually recognize that using a constant for a value used in dozens of places allows you to easily update that value in just one place  What is less often acknowledged is that this also prevents that value from being accidentally modified  because such a change would show everywhere  So  yes     is shorter than EMPTY  but EMPTY is safer to use than      So  coming back to the original question  we can only speculate that the language designers were probably not aware of this benefit of providing constants for literal values that are frequently used  Hopefully  we ll one day see string constants added in Java

User · Answer

It s funny how old this is and there is still no nice string class like there is in C   I have been doing Java for a few years now and I still also do c    When I do Java I miss the completeness of the c  language for strings  Mainly I miss string Empty and string IsNullOrEmpty string   I also really miss the lowercase string type      1 for adding this stuff to Java   All the workarounds are just that  Happy Coding in 2020 and beyond

User · Answer

I understand that every time I type the String literal     the same String object is referenced in the String pool  There s no such guarantee made  And you can t rely on it in your application  it s completely up to jvm to decide   or did the language creators simply not share my views  Yep  To me  it seems very low priority thing

[java] Why is there no String.Empty in Java?

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