如何将此链表存储在对象数组中?

时间:2017-03-21 23:43:16

标签: java linked-list

我有一个名为Sorting的类,它从用户接收一组整数,将它们存储在链表中,然后检查它们是否以递增的顺序存储。

现在它能够接收一个整数列表并存储它,然后检查它是否已排序。我需要能够存储两个单独的列表并检查它们,但我不确定如何存储它们。

我假设我应该将它存储在一个对象数组中但是如何将IntNode类对象存储在存储数组中呢?

以下是排序类:

import java.util.Scanner;

public class Sorting {

    public static IntNode[] storage = new IntNode[2];

    public static void main(String[] args) {
        Scanner input = new Scanner(System.in);

        IntNode head;
        head = new IntNode(0, null);
        int headCounter = 0;
        int searchNumber = 0;
        int nextInt;
        int storageNumber = 0;

        System.out.println("Please enter a seqeunce of integer numbers. When you are finished, enter a negative number");
        while (input.hasNextInt()) {
            nextInt = input.nextInt();
            if (nextInt >= 0) {
                if (headCounter == 0) {
                    head = new IntNode(nextInt, null);
                    searchNumber = nextInt;
                    headCounter++;
                    storageNumber++;
                } else {
                    IntNode selection = IntNode.listSearch(head, searchNumber);
                    selection.addNodeAfter(nextInt);
                    searchNumber = nextInt;
                    storageNumber++;
                }
            } else {
                headCounter = 0;
            }
        }

        for (IntNode cursor = head; cursor != null; cursor = cursor.getLink())
        System.out.print(cursor.getData() + " ");

        System.out.println(isSorted(head));

    }
    // Checks the linked list to see if the integers are sorted in increasing order
    // @param IntNode head
    //      The head of the linked list being checked
    // @return 
    //      The method returns true if the linked list is sorted in increasing order, and false if the 
    //      list is not sorted in an increasing order
    public static boolean isSorted(IntNode head) {
        int numCheckPrevious = 0;
        for (IntNode cursor = head; cursor != null; cursor = cursor.getLink()) {
            if (cursor.getData() > numCheckPrevious) {
                numCheckPrevious = cursor.getData();
                continue;
            } else {
                return false;
            }
        }
        return true;
    }
}

以下是将整数存储在链表中的IntNode类:

// File: IntNode.java 
/******************************************************************************
* An IntNode provides a node for a linked list with 
* integer data in each node.
*
* @note
*   Lists of nodes can be made of any length, limited only by the amount of
*   free memory in the heap. But beyond Integer.MAX_VALUE (2,147,483,647),
*   the answer from listLength is incorrect because of arithmetic
*   overflow. 
******************************************************************************/
public class IntNode
{
   // Invariant of the IntNode class:
   //   1. The node's integer data is in the instance variable data.
   //   2. For the final node of a list, the link part is null.
   //      Otherwise, the link part is a reference to the
   //      next node of the list.
   private int data;
   private IntNode link;   


   /**
   * Initialize a node with a specified initial data and link to the next
   * node. Note that the initialLink may be the null reference, 
   * which indicates that the new node has nothing after it.
   * @param initialData
   *   the initial data of this new node
   * @param initialLink
   *   a reference to the node after this new node--this reference may be null
   *   to indicate that there is no node after this new node.
   * @postcondition
   *   This node contains the specified data and link to the next node.
   **/   
   public IntNode(int initialData, IntNode initialLink)
   {
      data = initialData;
      link = initialLink;
   }


   /**
   * Modification method to add a new node after this node.   
   * @param item
   *   the data to place in the new node
   * @postcondition
   *   A new node has been created and placed after this node.
   *   The data for the new node is item. Any other nodes
   *   that used to be after this node are now after the new node.
   * @exception OutOfMemoryError
   *   Indicates that there is insufficient memory for a new 
   *   IntNode. 
   **/
   public void addNodeAfter(int item)   
   {
      link = new IntNode(item, link);
   }          


   /**
   * Accessor method to get the data from this node.   
   * @param - none
   * @return
   *   the data from this node
   **/
   public int getData( )   
   {
      return data;
   }


   /**
   * Accessor method to get a reference to the next node after this node. 
   * @param - none
   * @return
   *   a reference to the node after this node (or the null reference if there
   *   is nothing after this node)
   **/
   public IntNode getLink( )
   {
      return link;                                               
   } 


   /**
   * Copy a list.
   * @param source
   *   the head of a linked list that will be copied (which may be
   *   an empty list in where source is null)
   * @return
   *   The method has made a copy of the linked list starting at 
   *   source. The return value is the head reference for the
   *   copy. 
   * @exception OutOfMemoryError
   *   Indicates that there is insufficient memory for the new list.   
   **/ 
   public static IntNode listCopy(IntNode source)
   {
      IntNode copyHead;
      IntNode copyTail;

      // Handle the special case of the empty list.
      if (source == null)
         return null;

      // Make the first node for the newly created list.
      copyHead = new IntNode(source.data, null);
      copyTail = copyHead;

      // Make the rest of the nodes for the newly created list.
      while (source.link != null)
      {
         source = source.link;
         copyTail.addNodeAfter(source.data);
         copyTail = copyTail.link;
      }

      // Return the head reference for the new list.
    return copyHead;  // *   This node contains the specified data and link to the next node.

   }


   /**
   * Copy a list, returning both a head and tail reference for the copy.
   * @param source
   *   the head of a linked list that will be copied (which may be
   *   an empty list in where source is null)
   * @return
   *   The method has made a copy of the linked list starting at 
   *   source.  The return value is an
   *   array where the [0] element is a head reference for the copy and the [1]
   *   element is a tail reference for the copy.
   * @exception OutOfMemoryError
   *   Indicates that there is insufficient memory for the new list.   
   **/
   public static IntNode[ ] listCopyWithTail(IntNode source)
   {
      IntNode copyHead;
      IntNode copyTail;
      IntNode[ ] answer = new IntNode[2];

      // Handle the special case of the empty list.   
      if (source == null)
         return answer; // The answer has two null references .

      // Make the first node for the newly created list.
      copyHead = new IntNode(source.data, null);
      copyTail = copyHead;

      // Make the rest of the nodes for the newly created list.
      while (source.link != null)
      {
         source = source.link;
         copyTail.addNodeAfter(source.data);
         copyTail = copyTail.link;
      }

      // Return the head and tail references.
      answer[0] = copyHead;
      answer[1] = copyTail;
      return answer;
   }


   /**
   * Compute the number of nodes in a linked list.
   * @param head
   *   the head reference for a linked list (which may be an empty list
   *   with a null head)
   * @return
   *   the number of nodes in the list with the given head 
   * @note
   *   A wrong answer occurs for lists longer than Int.MAX_VALUE.     
   **/   
   public static int listLength(IntNode head)
   {
      IntNode cursor;
      int answer;

      answer = 0;
      for (cursor = head; cursor != null; cursor = cursor.link)
         answer++;

      return answer;
   }


   /**
   * Copy part of a list, providing a head and tail reference for the new copy. 
   * @param start/end
   *   references to two nodes of a linked list
   * @param copyHead/copyTail
   *   the method sets these to refer to the head and tail node of the new
   *   list that is created
   * @precondition
   *   start and end are non-null references to nodes
   *   on the same linked list,
   *   with the start node at or before the end node. 
   * @return
   *   The method has made a copy of the part of a linked list, from the
   *   specified start node to the specified end node. The return value is an
   *   array where the [0] component is a head reference for the copy and the
   *   [1] component is a tail reference for the copy.
   * @exception IllegalArgumentException
   *   Indicates that start and end are not references
   *   to nodes on the same list.
   * @exception NullPointerException
   *   Indicates that start is null.
   * @exception OutOfMemoryError
   *   Indicates that there is insufficient memory for the new list.    
   **/   
   public static IntNode[ ] listPart(IntNode start, IntNode end)
   {
      IntNode copyHead;
      IntNode copyTail;
      IntNode cursor;
      IntNode[ ] answer = new IntNode[2];

      // Make the first node for the newly created list. Notice that this will
      // cause a NullPointerException if start is null.
      copyHead = new IntNode(start.data, null);
      copyTail = copyHead;
      cursor = start;

      // Make the rest of the nodes for the newly created list.
      while (cursor != end)
      {
         cursor = cursor.link;
         if (cursor == null)
            throw new IllegalArgumentException
            ("end node was not found on the list");
         copyTail.addNodeAfter(cursor.data);
         copyTail = copyTail.link;
      }

      // Return the head and tail references
      answer[0] = copyHead;
      answer[1] = copyTail;
      return answer;
   }        


   /**
   * Find a node at a specified position in a linked list.
   * @param head
   *   the head reference for a linked list (which may be an empty list in
   *   which case the head is null)
   * @param position
   *   a node number
   * @precondition
   *   position > 0.
   * @return
   *   The return value is a reference to the node at the specified position in
   *   the list. (The head node is position 1, the next node is position 2, and
   *   so on.) If there is no such position (because the list is too short),
   *   then the null reference is returned.
   * @exception IllegalArgumentException
   *   Indicates that position is not positive.    
   **/   
   public static IntNode listPosition(IntNode head, int position)
   {
      IntNode cursor;
      int i;

      if (position <= 0)
           throw new IllegalArgumentException("position is not positive");

      cursor = head;
      for (i = 1; (i < position) && (cursor != null); i++)
         cursor = cursor.link;

      return cursor;
   }


   /**
   * Search for a particular piece of data in a linked list.
   * @param head
   *   the head reference for a linked list (which may be an empty list in
   *   which case the head is null)
   * @param target
   *   a piece of data to search for
   * @return
   *   The return value is a reference to the first node that contains the
   *   specified target. If there is no such node, the null reference is 
   *   returned.     
   **/   
   public static IntNode listSearch(IntNode head, int target)
   {
      IntNode cursor;

      for (cursor = head; cursor != null; cursor = cursor.link)
         if (target == cursor.data)
            return cursor;

      return null;
   }


   /**
   * Modification method to remove the node after this node.   
   * @param - none
   * @precondition
   *   This node must not be the tail node of the list.
   * @postcondition
   *   The node after this node has been removed from the linked list.
   *   If there were further nodes after that one, they are still
   *   present on the list.
   * @exception NullPointerException
   *   Indicates that this was the tail node of the list, so there is nothing
   *   after it to remove.
   **/
   public void removeNodeAfter( )   
   {
      link = link.link;
   }          


   /**
   * Modification method to set the data in this node.   
   * @param newData
   *   the new data to place in this node
   * @postcondition
   *   The data of this node has been set to newData.
   **/
   public void setData(int newData)   
   {
      data = newData;
   }                                                               


   /**
   * Modification method to set the link to the next node after this node.
   * @param newLink
   *   a reference to the node that should appear after this node in the linked
   *   list (or the null reference if there is no node after this node)
   * @postcondition
   *   The link to the node after this node has been set to newLink.
   *   Any other node (that used to be in this link) is no longer connected to
   *   this node.
   **/
   public void setLink(IntNode newLink)
   {                    
      link = newLink;
   }
}

1 个答案:

答案 0 :(得分:0)

要将节点插入存储阵列,首先假设您尚未初始化链接列表:

storage[0] = new IntNode(head_data, head_ptr);

如果您已初始化了链接列表,并且它以某些IntNode head开头,则可以将其存储在数组中,如下所示:

storage[0] = head;

如果您已经初始化了两个链接列表,则可以像这样存储它们:

storage[0] = head1;
storage[1] = head2;

您的IntNode[]数组已在主方法上方初始化,这就是您可以简单地设置数组的单独indeces的原因。

此处的storage数组将像其他数组(整数,字符等)一样工作,但有一个重要区别 - 如果您将IntNode插入数组,并将其更改为数组之外,它也会在你的数组中更改。