java - 从链接列表中删除所有出现的项目

Question

我已经为这个实验作业做了几个小时，但不明白为什么这段代码不起作用。问题是添加方法 int removeEvery(T item) 删除所有出现的 item 并将删除的项目数返回到实现链接列表接口(interface)的链接列表类。

这是我的代码:它删除了一些出现的项目，但不是全部。

public int removeEvery(T item){
int index = 0;
Node currentNode = firstNode;
for(int i = 1; i <= numberOfEntries; i++)
    {
    System.out.println(currentNode.getData());
        if (item.equals(currentNode.getData())){
            index++;
            remove(i);}
        else{
            currentNode = currentNode.getNextNode();}
    } 
        if(index != 0)
        return index;
    return -1;
}

这是包含在 LinkList 类中的 remove 方法:

public T remove(int givenPosition)
{
  T result = null;                 // return value

  if ((givenPosition >= 1) && (givenPosition <= numberOfEntries))
  {
     assert !isEmpty();
     if (givenPosition == 1)        // case 1: remove first entry
     {
        result = firstNode.getData();     // save entry to be removed 
        firstNode = firstNode.getNextNode();
        if (numberOfEntries == 1)
           lastNode = null; // solitary entry was removed
        }
        else                           // case 2: givenPosition > 1
        {
           Node nodeBefore = getNodeAt(givenPosition - 1);
           Node nodeToRemove = nodeBefore.getNextNode();
           Node nodeAfter = nodeToRemove.getNextNode();
           nodeBefore.setNextNode(nodeAfter);  // disconnect the node to be removed
           result = nodeToRemove.getData();  // save entry to be removed

           if (givenPosition == numberOfEntries)
              lastNode = nodeBefore; // last node was removed
     } // end if

     numberOfEntries--;
  } // end if

  return result;                   // return removed entry, or 
                                  // null if operation fails
} // end remove

Answer 1

您的链表有一些特别之处，您可以使用 current.getNextNode 访问下一个元素，但使用元素索引删除。您应该查看实现的其余部分是如何管理该索引的。第一个元素的索引是 0 还是 1(您从 1 开始循环)。当您删除一个元素时，所有元素的索引会发生什么。元素知道它们的索引吗？

你可以使用类似的东西

  int deletedNodes = 0;
  int currentIndex = 0; // check if 1 or 0
  currentNode = fist;
  while(currentNode != null){ // I guess lastNode.getNextNode() is null
    if(//should remove){
      remove(currentIndex);
      deletedNodes++
      // probably no need to change the index as all element should have been shifted back one index
    } else {
      currentIndex++; // index changes only if no node was deleted
    }
    currentNode = currentNode.getNextNode(); // will work even if it was deleted
  }
return deletedNodes;