我目前正在处理一个链表项目，但我对我的最后3个方法，我的removeWord（），concatenate（）和doubleChar（）感到困惑。我想知道是否有人可以给我一些提示我的内容我做错了。
class Node {
private char letter;
private Node next;
public Node(char ch, Node link) {
letter = ch;
next = link;
}
public void setLetter(char letter) {
this.letter=letter;
}
public char getLetter() {
return letter;
}
public void setNext(Node next) {
this.next=next;
}
public Node getNext() {
return next;
}
}
class Word {
// instance variable pointing to the head of the linked list
private Node head;
// default constructor
public Word() {
head = null;
}
// copy constructor
public Word(Word w) {
this.head = copy(w.head);
}
private static Node copy(Node l){
Node newL;
if( l ==null){
newL=null;
}else{
newL = new Node(l.getLetter(),copy(l.getNext()));
}
return newL;
}
// constructor from a String
public Word( String s ) {
Node pt;
head = null;
for( int i = s.length()-1; i >=0; i--){
pt = new Node(s.charAt(i),head);
head = pt;
}
}
// for output purposes -- override Object version
// no spaces between the characters, no linefeeds/returns
@Override
public String toString() {
//s.charAt
return toString(head);
// return toString(head);
}
private static String toString(Node L){
String Word="";
if (L == null){
// do nothing
}
else{
Word = L.getLetter() + toString(L.getNext());
// return the letter
}
return Word;
}
// remove the first occurrence of the Word w from this Word
public void removeWord( Word w ) {
head = removeWord(head,w);
}
private static Node removeWord(Node L, Word w)
{
if(L == null)
{
// do nothing
}else if(L==w.head){
L = L.getNext();
}
else {
// remove the word
L.setNext(removeWord(L.getNext(),w));
}
return L;
}
// concatenate a copy of s to the end of this Word
public void concatenate( Word s ) {
this.head = concatenate(head,s);
}
private static Node concatenate(Node L, Word s){
if( L==null){
L = null;
}
else{
L = new Node(L.getLetter(),concatenate(L.getNext(),s));
L.setNext(concatenate(L.getNext(),s));// add to the end of the list
}
return L;
}
// make a copy of every occurrence of ch in this Word
// for example, if this Word is abbcbccb, doubleChar ( 'b' ) should
// change the Word to abbbbcbbccbb
public void doubleChar( char ch ) {
head = doubleChar(head,ch);
}
public static Node doubleChar(Node L, char ch){
if(L == null)
{
}
else if(L.getLetter()==ch){
}
else{
//double
L.setNext(doubleChar(L.getNext(),ch));
}
return L;
}