Is there a goto statement in Java

Question

I m confused about this  Most of us have been told that there isn t any goto statement in Java   But I found that it is one of the keywords in Java  Where can it be used  If it can not be used  then why was it included in Java as a keyword

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No  goto is not used in Java  despite being a reserved word  The same is true for const  Both of these are used in C    which is probably the reason why they re reserved  the intention was probably to avoid confusing C   programmers migrating to Java  and perhaps also to keep the option of using them in later revisions of Java

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Because it s not supported and why would you want a goto keyword that did nothing or a variable named goto   Although you can use break label  and continue label  statements to effectively do what goto does  But I wouldn t recommend it   public static void main String    args          boolean t   true        first            second               third                   System out println  Before the break                    if  t                      break second                                   System out println  Not executed                             System out println  Not executed - end of second block                       System out println  End of third block

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It is important to understand that the goto construct is remnant from the days that programmers programmed in machine code and assembly language   Because those languages are so basic  as in  each instruction does only one thing   program control flow is done completely with goto statements  but in assembly language  these are referred to as jump or branch instructions      Now  although the C language is fairly low-level  it can be thought of as very high-level assembly language - each statement and function in C can easily be broken down into assembly language instructions   Although C is not the prime language to program computers with nowadays  it is still heavily used in low level applications  such as embedded systems   Because C s function so closely mirrors assembly language s function  it only makes sense that goto is included in C   It is clear that Java is an evolution of C C     Java shares a lot of features from C  but abstracts a lot more of the details  and therefore is simply written differently   Java is a very high-level language  so it simply is not necessary to have low-level features like goto when more high-level constructs like functions  for  for each  and while loops do the program control flow   Imagine if you were in one function and did a goto to a label into another function   What would happen when the other function returned   This idea is absurd     This does not necessarily answer why Java includes the goto statement yet won t let it compile  but it is important to know why goto was ever used in the first place  in lower-level applications  and why it just doesn t make sense to be used in Java

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To prohibit declarations of variables with the same name   e g   int i   0  goto

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Of course it is keyword  but it is not used on level of source code   But if you use jasmin or other lower level language  which is transformed to bytecode  then  goto  is there

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No  goto is not used  but you can define labels and leave a loop up to the label  You can use break or continue followed by the label  So you can jump out more than one loop level  Have a look at the tutorial

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Yes is it possible  but not as nice as in c   in my opinion c  is BETTER    Opinions that goto always obscures software are dull and silly  It s sad java don t have at least goto case xxx  Jump to forward   public static void main String    args       myblock         System out println  quot Hello quot         if  some condition         break myblock        System out println  quot Nice day quot               here code continue after performing break myblock    System out println  quot And work quot        Jump to backward   public static void main String    args       mystart    here code continue after performing continue mystart    do        System out println  quot Hello quot         if  some condition                  continue mystart        System out println  quot Nice day quot         while  false      System out println  quot And work quot

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goto is not in Java  you have to use  GOTO But it don t work correctly in key java word it is not used  http   docs oracle com javase tutorial java nutsandbolts  keywords html     public static void main String   args                            GOTO me                code              me                code

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Because although the Java language doesn t use it  JVM bytecode does

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The keyword exists  but it is not implemented   The only good reason to use goto that I can think of is this   for  int i   0  i  lt  MAX I  i          for  int j   0  j  lt  MAX J  j                 do stuff         goto outsideloops     to break out of both loops         outsideloops    In Java you can do this like this   loops  for  int i   0  i  lt  MAX I  i          for  int j   0  j  lt  MAX J  j                 do stuff         break loops

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They are reserved for future use  see  Java Language Keywords      The keywords const and goto are reserved  even though they are not currently used    The reason why there is no goto statement in Java can be found in  The Java Language Environment       Java has no goto statement  Studies illustrated that goto is  mis used more often than not simply  because it s there   Eliminating goto led to a simplification of the language--there are no rules about the effects of a goto into the middle of a for statement  for example  Studies on approximately 100 000 lines of C code determined that roughly 90 percent of the goto statements were used purely to obtain the effect of breaking out of nested loops  As mentioned above  multi-level break and continue remove most of the need for goto statements

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An example of how to use  continue  labels in Java is   public class Label       public static void main String   args            int temp   0          out     label         for  int i   0  i  lt  3    i                System out println  I am here                for  int j   0  j  lt  20    j                    if temp  0                        System out println  j      j                       if  j    1                            temp   j                          continue out     goto label  out                                                                          System out println  temp       temp             Results   I am here    i 0 j  0 j  1 I am here    i 1 I am here    i 2 temp   1

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James Gosling created the original JVM with support of goto statements  but then he removed this feature as needless  The main reason goto is unnecessary is that usually it can be replaced with more readable statements  like break continue  or by extracting a piece of code into a method   Source  James Gosling  Q amp A session

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As was pointed out  there is no goto in Java  but the keyword was reserved in case Sun felt like adding goto to Java one day  They wanted to be able to add it without breaking too much code  so they reserved the keyword  Note that with Java 5 they added the enum keyword and it did not break that much code either   Although Java has no goto  it has some constructs which correspond to some usages of goto  namely being able to break and continue with named loops  Also  finally can be thought of as a kind of twisted goto

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I m not a fan of goto either  as it usually makes code less readable  However I do believe that there are exceptions to that rule  especially when it comes to lexers and parsers    Of Course you can always bring your program into Kleene Normalform by translating it to something assembler-like and then write something like  int line   1  boolean running   true  while running        switch line                  case 1     line 1                    break          case 2     line 2                    break                      case 42  line   1337     goto 1337                 break                      default  running   false                  break             So you basically write a VM that executes your binary code    where line corresponds to the instruction pointer   That is so much more readable than code that uses goto  isn t it

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No  thankfully  there isn t goto in Java   The goto keyword is only reserved  but not used  the same goes for const

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It s very much considered one of those things you Do Not Do  but was probably listed as a reserved word to avoid confusion for developers

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http   java sun com docs books tutorial java nutsandbolts  keywords html      The keywords const and goto are   reserved  even though they are not   currently used

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See the following link is shows all java reserved words and tells you what versions they where added   http   java sun com docs books tutorial java nutsandbolts  keywords html  goto is reserved  even though it is not currently used  never say never however

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So they could be used one day if the language designers felt the need   Also  if programmers from languages that do have these keywords  eg  C  C    use them by mistake  then the Java compiler can give a useful error message   Or maybe it was just to stop programmers using goto

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http   docs oracle com javase specs jvms se7 html jvms-6 html jvms-6 5 goto  If you have been told that there is no goto statement in Java you have been fooled  Indeed  Java consists two layers of  source  code

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The Java keyword list specifies the goto keyword  but it is marked as  not used    It was in the original JVM  see answer by  VitaliiFedorenko   but then removed  It was probably kept as a reserved keyword in case it were to be added to a later version of Java   If goto was not on the list  and it gets added to the language later on  existing code that used the word goto as an identifier  variable name  method name  etc     would break  But because goto is a keyword  such code will not even compile in the present  and it remains possible to make it actually do something later on  without breaking existing code

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Note that you can replace most of the benign uses of goto by   return break break label throw inside try-catch-finally

[java] Is there a goto statement in Java?

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