以下是我的控制台日志输出...用户输入要添加的整数，以及他们希望切换的元素的索引：
输入要添加的整数：4
输入另一个要添加的整数：5
输入另一个要添加的整数：6
输入另一个要添加的整数：7
输入另一个要添加的整数：8
双向链表的节点：
4 5 6 7 8
输入您要交换的元素的索引：2
双向链表的节点：
4 5 6 7 8
...但是，最后一行当然应该是45768
package ass1Q2A;
public class SLList {
public SLNode head = null;
public SLNode tail = null;
public void add(int a) { //adds new element to our single-linked list.
SLNode newNode = new SLNode(a);
if (head == null) {
head = newNode;
tail = newNode;
} else {
tail.next = newNode;
tail = newNode;
}
}
//THIS SLSWAP METHOD IS WHERE I THINK THE ERROR IS:
public void SLswap(int i) throws illegalOperation { //i is index of node to change. method swaps specified node of index "i" with following node.
if(i>=(size()-1))
throw new illegalOperation("must swap one of the nodes, OR there does not exist node after tail");
if (size() < 2)
throw new illegalOperation("cant swap if theres less than two elements");
else if (size() == 2) {
SLNode placeholder = tail;
tail = head;
head = placeholder;
} // end else if
else { //LOGICAL ERROR MUST EXIST IN THIS ELSE STATEMENT
SLNode iterationNode = head;
for (int j = 0; j<i; i++) {//order of pointing: iterationNode => iterationNode.next => nodeB => iterationNode.next.next.NEXT
if (j==(i-1)) { //GOAL: swap iterationNode.next with nodeB(iteraitonNode.next.next)
SLNode nodeB = iterationNode.next.next;
iterationNode.next.next = iterationNode.next.next.next;
nodeB.next = iterationNode.next;
iterationNode.next = nodeB;
break;
}
iterationNode = iterationNode.next; //iterate to next node
} // end for-loop
}
}
public int size() {//returns number of nodes in SingleLinkedList
SLNode u = head;
int size = 0;
while (u != null) {
size++;
u = u.next;
}
return size;
}
public void display() { //prints values of all nodes in SLL, starting from head
SLNode current = head;
if(head == null) {
System.out.println("List is empty");
return;
}
System.out.println("Nodes of doubly linked list: ");
while(current != null) {
//Prints each node by incrementing the pointer.
System.out.print(current.data + " ");
current = current.next;
}
}
public static void main(String[] args) {
//EVERYTHING WORKS BUT SWAP METHOD... LOGICAL ERROR?
SLList myList = new SLList();
//Add nodes to the list
int toAdd1 = IOHelper.getInt("enter integer to add:");
int toAdd2 = IOHelper.getInt("enter another integer to add:");
int toAdd3 = IOHelper.getInt("enter another integer to add:");
int toAdd4 = IOHelper.getInt("enter another integer to add:");
int toAdd5 = IOHelper.getInt("enter another integer to add:"); //completed prompting user for input data for SinglyLinkedList
myList.add(toAdd1);
myList.add(toAdd2);
myList.add(toAdd3);
myList.add(toAdd4);
myList.add(toAdd5); //completed adding user-inputted data to SinglyLinkedList
myList.display(); //Displays the nodes present in the SLList before any swapping takes place
int indexToSwap = IOHelper.getInt("enter the index of the element that you would like to swap:"); //prompt user for index he/she wishes to swap
try {
try {
myList.SLswap(indexToSwap); //call SLSwap with user-inputted index
}catch(NullPointerException i) {};
}catch(illegalOperation e) {};
myList.display(); //display list after the switch
}
}
public class SLNode {
int data; //data that a node holds
SLNode next; // next node in the SSList that this given node will point to
public SLNode(int data) {
this.data = data;
this.next = null;
}
}