// Converting array to List to Collection to array // Convert an array to a List: final String[] animals = { "bear", "cougar", "wolverine"}; final List<String> list = Arrays.asList( animals ) ); // A List can then be fed to the constructor or addAll method // of many Collections: final Collection<String> h = new HashSet<String>( list ); // Convert a Collection back to an array, no (String[]) cast needed. final String[] predators = h.toArray( new String[ h.size() ] ); // The above toArray technique works only with // Object[], not int[], short[], long[] etc. // To extract a primitive array you need code like this: final List<Short> reps = new ArrayList( 10 ); ... final short[] reparray = new short[ reps.size() ]; int i = 0; // autounboxing Short -> short for ( short rep: reps ) { reparray[ i++ ] = rep; }