為什么我的方法無法按字母順序對鏈接列表進行排序？

Question

public class doubleLinkedList {

    class Node {
      String value;
      Node prev;
      Node next;

      Node(String val, Node p, Node n) {
        value = val;
        prev = p;
        next = n;
      }

      Node(String val) {
        value = val;
        prev = null;
        next = null;
      }
    }

    Node first;
    Node last;

    public doubleLinkedList() {
      first = null;
      last = null;
    }

    public boolean isEmpty() {
      if (first == null)
        return true;
      else
        return false;
    }

    /**The size method returns the length of the linked list
     * @return the number of element in the linked list
    */
    public int size() {
      int count = 0;
      Node traverse = first;
      while (traverse != null) {
        count++;
        traverse = traverse.next;
      }
      return count;
    }


    public void add(String element) {

      if (isEmpty()) {
        first = new Node(element);
        last = first;
      } else {

        Node p = first;
        Node elementTobeAdded;
        while (((p.value).compareTo(element)) > 0 && p.next != null) {
          p = p.next;
        }

        if (p.next != null) {
          elementTobeAdded = new Node(element, p, p.next);
          p.next.prev = elementTobeAdded;
          p = elementTobeAdded.prev;
        } else {
          elementTobeAdded = new Node(element, p, null);
          p.next = elementTobeAdded;
          elementTobeAdded.next = null;
          last = elementTobeAdded;
        }

      }
    }

    public void printForward() {
      Node printNode = first;
      while (printNode != null) {
        System.out.print(printNode.value + ", ");
        printNode = printNode.next;
      }
    }
  }
  public class test {

    public static void main(String[] args) {
      doubleLinkedList car = new doubleLinkedList();
      car.add("Jeep");
      car.add("benz");
      car.add("Honda");
      car.add("Lexus");
      car.add("BMW");
      car.printForward();
    }
  }

我的add方法嘗試按字母順序將節點添加到列表中。 我的printForward方法打印出列表中的每個元素。 在我的主要方法中，它打印出“吉普，奔馳，本田，寶馬”，但不是按字母順序排列。

Answer 1

從這里更改add方法的非空大小寫

  Node p = first;

  Node elementTobeAdded;

  while(((p.value).compareTo(element)) > 0 && p.next != null)
  {
    p = p.next;
  }

  if(p.next != null)
  {
  elementTobeAdded = new Node(element,p,p.next);
  p.next.prev = elementTobeAdded;
  p = elementTobeAdded.prev;
  }

  else
  {
    elementTobeAdded = new Node(element, p, null);
    p.next = elementTobeAdded;
    elementTobeAdded.next = null;
    last = elementTobeAdded;
  }

對此：

  Node p = first;
  while (p.value.compareTo(element) < 0 && p.next != null) {
    p = p.next;
  }
  if (p.value.compareTo(element) > 0) {
    Node toAdd = new Node(element, p.prev, p);
    p.prev = toAdd;
    if (toAdd.prev != null) {
        toAdd.prev.next = toAdd;
    }else {
      first = toAdd;
    }
  }else {
    Node toAdd = new Node(element, p, p.next);
    p.next = toAdd;
    if (toAdd.next != null) {
        toAdd.next.prev = toAdd;
    }else {
      last = toAdd;
    }
  }

這里有很多錯誤。 最大的問題是您從未檢查過將新元素插入列表開頭的情況。 即使第一個元素應該放在最前面，也總是在其后插入一個新元素。

請注意，“ benz”位於末尾，因為String.compareTo方法將大寫字母視為小寫字母之前的大寫字母。

Answer 2

它不是一個鏈表...您編寫了某種隊列（可以選擇使它出隊）。

關於您的問題-您的“添加”方法存在錯誤-至少您不檢查是否有必要前進。 您可能還有其他錯誤，但是很難讀取此類樣式的源代碼（請修復您的問題格式）...