Execute Groovy Online

/* Hello World in Groovy */
println("Hello world")
List<String> row1 = Arrays.asList("00", "01", "02");
List<String> row2 = Arrays.asList("10", "11", "12");
List<String> row3 = Arrays.asList("20", "21", "22");
List<String> row4 = Arrays.asList("30", "31", "32");
List<List> originalList = Arrays.asList(row1, row2, row3,row4);

List<List> columnList = new ArrayList<List>(originalList.size());
for(int i=0; i < originalList.size() ; i++){
    List<List> originalRow = originalList[i];
    for(int j=0; j < originalRow.size(); j++){
        System.out.println(originalRow.get(j));
    }
}