编译运行以下代码( ) import java.util.*; class ComicBooks{ public static void main(String[] args){ Map comics = new TreeMap(); comics.put(new Integer(101),"Year One pt 1"); comics.put(new Integer(102),"Year Two pt 1"); comics.put(new Integer(103),"Once upon a time"); comics.put(new Integer(104),null); System.out.println(comics); } }