Array initialization syntax when not in a declaration

Question

I can write   AClass   array    object1  object2    I can also write   AClass   array   new AClass 2       array 0    object1  array 1    object2    but I can t write   AClass   array      array    object1  object2     Why is this blocked by Java   I know how to work around it  but from time to time it would be simpler   For example   public void selectedPointsToMove cpVect coord         if  tab    null            if  arePointsClose coord  point1  10                 cpVect   tempTab    point1               tab   tempTab            else if  arePointsClose point2  coord  10                 cpVect   tempTab    point2               tab   tempTab            else               cpVect   tempTab    point1 point2               tab   tempTab                      This simple question that has been bugging me since I learned how to play with arrays in Java

User · Answer

I can t answer the why part   But if you want something dynamic then why don t you consider Collection ArrayList   ArrrayList can be of any Object type   And if as an compulsion you want it as an array you can use the toArray   method on it   For example               ArrayList lt String gt  al   new ArrayList lt String gt                 al add  one                al add  two                String   strArray    String    al toArray new String 0      I hope this might help you

User · Answer

Why is this blocked by Java    You d have to ask the Java designers  There might be some subtle grammatical reason for the restriction  Note that some of the array creation   initialization constructs were not in Java 1 0  and  IIRC  were added in Java 1 1   But  why  is immaterial     the restriction is there  and you have to live with it      I know how to work around it  but from time to time it would be simpler    You can write this   AClass   array      array   new AClass   object1  object2

User · Answer

I ll try to answer the why question  The Java array is very simple and rudimentary compared to classes like ArrayList  that are more dynamic  Java wants to know at declaration time how much memory should be allocated for the array  An ArrayList is much more dynamic and the size of it can vary over time   If you initialize your array with the length of two  and later on it turns out you need a length of three  you have to throw away what you ve got  and create a whole new array  Therefore the  new  keyword    In your first two examples  you tell at declaration time how much memory to allocate  In your third example  the array name becomes a pointer to nothing at all  and therefore  when it s initialized  you have to explicitly create a new array to allocate the right amount of memory   I would say that  and if someone knows better  please correct me  the first example   AClass   array    object1  object2    actually means   AClass   array   new AClass   object1  object2     but what the Java designers did  was to make quicker way to write it if you create the array at declaration time    The suggested workarounds are good  If the time or memory usage is critical at runtime  use arrays  If it s not critical  and you want code that is easier to understand and to work with  use ArrayList

User · Answer

For those of you  who doesn t like this monstrous new AClass           syntax  here s some sugar   public AClass   c AClass    arr    return arr      Use this little function as you like   AClass   array      array   c object1  object2

[java] Array initialization syntax when not in a declaration

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