importjava.util.Collection;importjava.util.HashSet;importjava.util.Iterator;importjava.util.LinkedList;publicclassA{publicvoidgetList(Stringstr){LinkedListl=newLinkedList();for(inti=0;i0){System.out.println(l.getFirst());;l.removeFirst();}}}System.out.println("最后结果:");if(l.size()==0){System.out.println("最后的栈里不存在内容");}for(inti=0;i