我有我制作的这个链表类，我知道如何测试它，你认为它有效吗？或者你能解释一下我如何测试它吗？
public class List {
private int size;
private Node head;
private Node current;
private Node prev;
private Node temp;
/**
* Creates an empty list.
* @pre none
* @post and empty list is created
*/
public List(){
head = null;
}
/**
* Delete the current element from this list. The element after the deleted element becomes the new current.
* If that's not possible, then the element before the deleted element becomes the new current.
* If that is also not possible, then you need to recognize what state the list is in and define current accordingly.
* Nothing should be done if a delete is not possible.
* @pre there is a current element
* @post the item current pointed to is removed, the element before or after is the new current
*/
public void delete(){
if(current.getNext() != null){
current = current.getNext();
prev.setNext(current);
size--;
}
else
if(current.getNext() == null){
current = prev;
current.setNext(null);
resetPrev();
size--;
}
}
/**
* Get the value of the current element. If this is not possible, throw an IllegalArgumentException.
* @pre the list is not empty
* @post the current element's data is returned
* @return value of the current element.
*/
public char get(){
return current.getItem();
}
/**
* Go to the last element of the list. If this is not possible, don't change the cursor.
* @pre there is a current element
* @post current is now the last element in the list
*/
public void goLast(){
while (current.getNext() != null){
current = current.getNext();
}
}
/**
* Advance the cursor to the next element. If this is not possible, don't change the cursor.
* @pre there is a current element
* @post current is now the element after what it was
*/
public void goNext(){
if(current.getNext() != null){
current = current.getNext();
}
//else do nothing
}
/**
* Retreat the cursor to the previous element. If this is not possible, don't change the cursor.
* @pre
* @post
*/
public void goPrev(){
current = prev;
resetPrev();
}
/**
* Go to top of the list. This is the position before the first element.
* @pre
* @post
*/
public void goTop(){
}
/**
* Go to first element of the list. If this is not possible, don't change the cursor.
* @pre none
* @post current is now pointing to the first node of the list, the head
*/
public void goFirst(){
current = head;
}
/**
* Insert the given parameter after the current element. The newly inserted element becomes the current element.
* @pre none
* @post newVal is inserted into the list and is now the current element
* @param newVal is the value to insert after the current element.
*/
public void insert(char newVal){
if(head == null){
head = new Node(newVal);
size++;
}
else{
Node current = head;
while(current.getNext() != null){
current = current.getNext();
}
Node prev = current;
current = new Node(newVal);
prev.setNext(current);
size++;
}
}
/**
* Determines if this list is empty. Empty means this list has no elements.
* @pre none
* @post a boolean value of the state of the list is returned
* @return true if the list is empty.
*/
public boolean isEmpty(){
return head == null;
}
/**
* Determines the size of the list. The size of the list is the number of elements in the list.
* @pre none
* @post size is accessed and returned
* @return size which is the number of elements in the list.
*/
public int size(){
return size;
}
public void resetPrev(){
//reset prev to prev's previous
Node temp = head;
while(temp != current){
temp = temp.getNext();
}
prev = temp;
}
public class Node {
private char item;
private Node next;
public Node(char val) {
this.item = val;
}
public char getItem() {
return this.item;
}
public Node getNext() {
return this.next;
}
public void setNext(Node next) {
this.next = next;
}
}
}
感谢您的帮助，我仍然很新，所以我不确定如何做这些，我什至不确定它是否一直有效，这就是我想测试它的原因！