集合LinkedList 的特有功能

public static void main(String[] args) {    LinkedList l=new LinkedList();    l.addFirst("a");                        //添加    l.addFirst("b");    l.addFirst("c");                        //添加    l.addFirst("d");    l.addFirst("e");                        //添加    l.addFirst("f");    l.addLast("g");    System.out.println(l);    System.out.println(l.getFirst());       //获取    System.out.println(l.getLast());    System.out.println(l.removeFirst());    //删除    System.out.println(l.removeLast());    System.out.println(l.get(2));           //根据索引获取,从头或从尾开始查找}