[英]Java - Trying to sort a LinkedList with a custom comparator, cannot find symbol sort
[英]Sort Linkedlist with Comparator and Generics java
我正在嘗試使用泛型對鏈表進行排序,但是在某些轉換問題上遇到了麻煩。 代碼拋出錯誤,無法將Bus強制轉換為Node。 我知道問題出在比較器(我轉換為Bus的地方)中,但是否則我不知道如何調用Bus中定義的方法(與Bus還是另一個Object無關,只用一個隨機對象進行測試)。 我一直在研究互聯網,但找不到解決方案。 這是代碼:
/**
* Swaps the current node's element with the previous one
*/
public void swap(){
Object previous = getCurrent().getElement();
Object current = next().getElement();
getCurrent().setElement(previous);
previous().setElement(current);
}
public AbstractList<T> orderBy(Comparator<Node<T>> comparator){
setCurrent(getFirst());
Node<T> aux;
Node<T> current;
boolean check = true;
while (check){
check = false;
aux = getFirst();
current = getFirst().getNext();
while(hasNext()) {
if (comparator.compare(aux, current) > 0) {
check = true;
swap();
}
aux = current;
current = current.getNext();
}
}
return this;
}
比較器:
import java.util.Comparator;
public class InternComparator implements Comparator<Node<Bus>>{
@Override
public int compare(Node<Bus> o1, Node<Bus> o2) {
return ((Bus)o1.getElement()).getIntern() - ((Bus)o2.getElement()).getIntern();
} //getIntern() returns an Integer
摘要列表(由教授提供):
import java.util.NoSuchElementException;
public class AbstractList<T> {
private Node<T> first;
private Node<T> current;
private Node<T> last;
private int size = 0;
public boolean hasNext(){
return current != last;
}
public boolean hasPrevious(){
return current != first;
}
public Node getCurrent(){
return current;
}
public void setCurrent(Node<T> current) {
this.current = current;
}
public int size(){
return size;
}
public boolean isEmpty(){
return first == last || first == null;
}
public void add(T t){
Node<T> a = new Node<T>(t);
if(first == null){
first = a;
}
if(last == null && first != null){
last = a;
last.setPrevious(first);
first.setNext(last);
}
Node<T> aux = last;
last.setNext(a);
last = a;
last.setPrevious(aux);
current = last;
size++;
}
public Node next(){
if(!hasNext()){
throw new RuntimeException("No elements available next.");
}
current = current.getNext();
return current;
}
public Node previous(){
if(!hasPrevious()){
throw new RuntimeException("No elements available previous.");
}
current = current.getPrevious();
return current;
}
public Node getFirst(){
return first;
}
public Node getLast(){
return last;
}
public void setFirst(Node<T> first){
this.first = first;
}
public void setLast(Node<T> last) {
this.last = last;
}
public void remove(T t){
current = first;
boolean removed = false;
while (hasNext()) {
if (current.getElement() == t || current.getElement().equals(t)) {
if(current != last && current != first) {
current.getNext().setPrevious(current.getPrevious());
current.getPrevious().setNext(current.getNext());
} else if(current == first){
current.getNext().setPrevious(null);
} else if(current == last){
current.getPrevious().setNext(null);
}
removed = true;
return;
}
current = next();
}
if(removed){
size--;
} else {
throw new NoSuchElementException("No such element on the list.");
}
}
public Node goTo(int pos){
if(pos > size){
throw new ArrayIndexOutOfBoundsException("Inexistent Position");
}
current = first;
for(int i = 0; i < pos; i++){
current = next();
}
return current;
}
public void insertAfter(T t){
Node<T> aux = new Node<>(t);
if(current != last) {
Node<T> next = current.getNext();
Node<T> previous = current;
current.getNext().setPrevious(aux);
current.setNext(aux);
aux.setNext(next);
aux.setPrevious(previous);
} else {
current.setNext(aux);
aux.setPrevious(current);
last = aux;
}
size++;
}
public void insertPrevious(T t){
Node<T> aux = new Node<>(t);
if(current != first) {
Node<T> previous = current.getPrevious();
Node<T> next = current;
current.getPrevious().setNext(aux);
current.setPrevious(aux);
aux.setNext(next);
aux.setPrevious(previous);
} else {
Node<T> aux1 = current;
current.setPrevious(aux);
first = aux;
first.setNext(aux1);
}
size++;
}
@Override
public String toString() {
String result = "";
current = first;
while(hasNext()) {
result += current.getElement() + "";
next();
}
return result;
}
}
class Node<T> {
private Object element;
private Node<T> prev;
private Node<T> next;
public Node(T element){
this.element = element;
}
public Node(T element, Node next){
this.element = element;
this.next = next;
}
public Node<T> getNext() {
return next;
}
public Node<T> getPrevious() {
return prev;
}
public Object getElement() {
return element;
}
public void setNext(Node<T> next) {
this.next = next;
}
public void setPrevious(Node<T> prev) {
this.prev = prev;
}
public void setElement(Object element) {
this.element = element;
}
}
再想想:您的對象的類型為Node<Bus>
; 您想知道為什么投向Bus
失敗?
還是換個說法:您是否假設Bus<People>
代表一個人?
如果您有容器 ,則必須檢索包含的值; 而通過鑄造容器是無法實現的!
或者,為了繼續使用奇怪的圖片:您不會通過聲明盒子是雞蛋來開箱即用。 您打開盒子,取出雞蛋。
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