How can I initialize an array without knowing it size

Question

I have a situation  where I have to apply a criteria on an input array and reuturn another array as output which will have smaller size based upon the filtering criteria     Now problem is I do not know the size of filtered results  so I can not initialize the array with specific value  And I do not want it to be large size will null values because I am using array length  later on     One way is to first loop the original input array and set a counter  and then make another loop with that counter length and initialize and fill this array    But is there anyway to do the job in just one loop

User · Answer

Just return any kind of list  ArrayList will be fine  its not static       ArrayList lt yourClass gt  list   new ArrayList lt yourClass gt     for  yourClass item   yourArray        list add item

User · Answer

You can t    an array s size is always fixed in Java  Typically instead of using an array  you d use an implementation of List lt T gt  here - usually ArrayList lt T gt   but with plenty of other alternatives available   You can create an array from the list as a final step  of course - or just change the signature of the method to return a List lt T gt  to start with

User · Answer

Use LinkedList instead  Than  you can create an array if necessary

User · Answer

Here is the code for you r class   but this also contains lot of refactoring  Please add a for each rather than for  cheers      static int isLeft ArrayList lt String gt  left  ArrayList lt String gt  right                 int f   0          for  int i   0  i  lt  left size    i                  for  int j   0  j  lt  right size    j                                   if  left get i  charAt 0     right get j  charAt 0                         System out println  Grammar is left recursive                        f   1                                                     return f              public static void main String   args               TODO code application logic here         ArrayList lt String gt  left   new ArrayList lt String gt             ArrayList lt String gt  right   new ArrayList lt String gt               Scanner sc   new Scanner System in           System out println  enter no of prod            int n   sc nextInt            for  int i   0  i  lt  n  i                  System out println  enter left prod                String leftText   sc next                left add leftText               System out println  enter right prod                String rightText   sc next                right add rightText                      System out println  the productions are            for  int i   0  i  lt  n  i                  System out println left get i     - gt     right get i                      int flag          flag   isLeft left  right           if  flag    1                System out println  Removing left recursion              else               System out println  No left recursion

[java] How can I initialize an array without knowing it size?

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