(Solved) Merge Arraylists inside an ArrayLists of Arraylists [closed]
The following method should do the trick: public static <T> void merge(ArrayList<ArrayList<T>> arrayLists) { int blockSize = 6; for(int i=blockSize; i<arrayLists.size(); i++) { arrayLists.get(i % blockSize).addAll(arrayLists.get(i)); } arrayLists.subList(blockSize, arrayLists.size()).clear(); } You can convert blockSize to the method parameter if you like. 1 solved Merge Arraylists inside an ArrayLists of Arraylists [closed]