this is my whole class ,I have added number 2 to the doubly linked list and then I want it to be be print in the concole but it will show this "datastructureproject.Node@f62373" thanks!
package datastructureproject;
public class DoublyLinkedList {
private Node head = new Node(0);
private Node tail = new Node(0);
private int length = 0;
public DoublyLinkedList() {
head.setPrev(null);
head.setNext(tail);
tail.setPrev(head);
tail.setNext(null);
}
public void add(int index, int value) throws IndexOutOfBoundsException {
Node cursor = get(index);
Node temp = new Node(value);
temp.setPrev(cursor);
temp.setNext(cursor.getNext());
cursor.getNext().setPrev(temp);
cursor.setNext(temp);
length++;
}
private Node get(int index) throws IndexOutOfBoundsException {
if (index < 0 || index > length) {
throw new IndexOutOfBoundsException();
} else {
Node cursor = head;
for (int i = 0; i < index; i++) {
cursor = cursor.getNext();
}
return cursor;
}
}
public long size() {
return length;
}
public boolean isEmpty() {
return length == 0;
}
@Override
public String toString() {
StringBuffer result = new StringBuffer();
result.append("(head) - ");
Node temp = head;
while (temp.getNext() != tail) {
temp = temp.getNext();
result.append(temp.getValue() + " - ");
}
result.append("(tail)");
return result.toString();
}
public static void main(String[] args){
DoublyLinkedList list = new DoublyLinkedList();
list.add(0,2 );
System.out.println(list.get(0).toString());
}
}
EDITED: also this is my Node class, thanks!
class Node {
public int value;
public Node(){
}
public void setValue(int value) {
this.value = value;
}
public Node next;
public Node prev;
public Node(int value) {
this.value = value;
}
public Node(int value, Node prev, Node next) {
this.value = value;
setNext(next);
setPrev(prev);
}
public void setNext(Node next) {
this.next = next;
}
public void setPrev(Node prev) {
this.prev = prev;
}
public Node getNext() {
return next;
}
public Node getPrev() {
return prev;
}
public int getValue() {
return value;
}
}
You've overridden toString()
on the DoubleLinkedList
but you're calling it on a Node
. Call list.toString()
or override Node.toString()
if you only want to print the node's content.
您需要在Node类中重写toString()。
The output is revealing:
"datastructureproject.Node@f62373"
This is what a class Node
in package datastructureproject
would return in its toString()
that is inherited from Object
.
You also need to @Override
the public String toString()
method in your Node
class if you want the nodes themselves to return something else on toString()
.
Your Node class does not override the toString() method and falls back to use the Object.toString() method instead.
Also I think it is a bit confusing that you add a value but return a Node instead of a value with get().
Update: to print the value of your Node add the following code to your Node class.
@Override public String toString(){return ""+ value;}
Or you can change the get method in DoublyLinkedList to
public int get(int index) throws IndexOutOfBoundsException {
if (index < 0 || index > length) {
throw new IndexOutOfBoundsException();
} else {
Node cursor = head;
for (int i = 0; i < index; i++) {
cursor = cursor.getNext();
}
return cursor.getValue();
}
}
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