question: protected static int [ ] concat ( @ Nullable int [ ] arr , int ... obj ) { int [ ] newArr ; if ( arr == null || arr . length == 0 ) newArr = obj ; else { newArr = Arrays . copyOf ( arr , arr . length + obj . length ) ; System . arraycopy ( obj , 0 , newArr , arr . length , obj . length ) ; } return newArr ; }
target:  Concatenates elements to an int array.