【发布时间】：2020-03-08 13:24:57
【问题描述】：
所以我正在做一个涉及链接列表的项目。我们必须自己制作节点和链表（不允许使用 Java 提供的）。作为项目的一部分，我正在制作一个列表，该列表将根据某些标准自动调整（当输入的单词与已经存在的单词相同时，将该节点移动到列表的前面）。我的代码似乎运行良好，但经过一段时间后，它就停止运行。当我尝试调试它时，Eclipse 只是暂停了该过程，我不知道为什么，因为它完全没有提供任何反馈。它似乎在其中一个 while 循环中，但我似乎无法弄清楚原因。任何帮助将不胜感激。代码比较长，所以我把它贴在这堵文字墙下面。我在编程方面还不是很有经验，所以你可能会注意到一些错误/烦恼。
SelfAdjustingListOne.java
public class SelfAdjustingListOne extends UnsortedList
{
public SelfAdjustingListOne()
{
super();
}
public SelfAdjustingListOne(long timer)
{
super(timer);
}
public void adjustingAdd(Node input)
{
// If there's nothing in the list, make this the first and last node
if (getFront() == null)
{
setFront(input);
setBack(input);
input.setIndex(0);
} else if (sameWord(input) != null)
{
// If the word already exists, increment the word count and send that node to
// the front of the list
Node sameString = sameWord(input), current = getFront(), previous;
try
{
// Will return null if sameString is the first node on the list
previous = getByIndex(sameString.getIndex() - 1);
} catch (NullPointerException e)
{
previous = null;
}
// If sameString is the first node, no link needs to be set
if (previous != null)
previous.setLink(sameString.getLink());
// Link the node we are moving to the front node
sameString.setLink(getFront());
// Set the value of the front node to the node we are moving
setFront(sameString);
// Increment its count
sameString.plusCount();
// While the current node exists and has not surpassed the previous location of
// the node we moved, increment the index value of each node by 1
while (current != null && current.getIndex() != sameString.getIndex())
{
current.plusIndex();
current = current.getLink();
}
// Set the new front node's index to 0 (Beginning of the list)
sameString.setIndex(0);
plusComparisons();
plusComparisons();
} else
{
// If the list has at least one node and the word being added doesn't exist, add
// this node to the front of the list
input.setLink(getFront());
Node current = getFront();
while (current != null)
{
current.plusIndex();
current = current.getLink();
}
setFront(input);
input.setIndex(0);
plusComparisons();
plusNodeChanges();
plusNodeChanges();
}
}
}
UnsortedList.java
import java.text.DecimalFormat;
public class UnsortedList
{
private Node front;
private Node back;
private Long timer;
private int numOfComparisons;
private int nodeChanges;
public UnsortedList()
{
}
public UnsortedList(long timer)
{
this.timer = timer;
}
public void addBack(Node input)
{
if (front == null)
{
setFront(input);
setBack(input);
input.setIndex(0);
} else if (sameWord(input) != null)
{
Node sameString = sameWord(input);
sameString.plusCount();
numOfComparisons += 2;
} else
{
getBack().setLink(input);
input.setIndex(back.getIndex() + 1);
setBack(input);
numOfComparisons++;
nodeChanges += 2;
}
}
public void addFront(Node input)
{
if (front == null)
{
setFront(input);
setBack(input);
input.setIndex(0);
} else if (sameWord(input) != null)
{
Node sameString = sameWord(input);
sameString.plusCount();
numOfComparisons += 2;
} else
{
input.setLink(front);
Node current = front;
while (current != null)
{
current.plusIndex();
current = current.getLink();
}
setFront(input);
input.setIndex(0);
numOfComparisons++;
nodeChanges += 2;
}
}
public void remove(int index)
{
Node current = front;
do
{
if (current.getIndex() == index - 1)
{
if (current.getLink().getLink() != null)
{
current.getLink().setIndex(-1);
current.setLink(current.getLink().getLink());
Node currentIndexNode = current.getLink();
while (currentIndexNode != null)
{
currentIndexNode.minusIndex();
currentIndexNode = currentIndexNode.getLink();
}
} else
{
current.getLink().setIndex(-1);
current.setLink(null);
}
}
current = current.getLink();
} while (!current.isEqual(back));
}
public void setFront(Node input)
{
front = input;
}
public void setBack(Node input)
{
back = input;
}
public Node getFront()
{
return front;
}
public Node getBack()
{
return back;
}
public Node getByIndex(int index) throws NullPointerException
{
Node current = front, currentIndexNode = current.getLink();
while (current != null)
{
do
{
if (current.getIndex() == index)
return current;
current = currentIndexNode;
currentIndexNode = currentIndexNode.getLink();
} while (currentIndexNode != null);
}
return null;
}
public Node getByWord(String word) throws NullPointerException
{
Node current = front, currentIndexNode = current.getLink();
while (current != null)
{
do
{
if (current.getWord().equalsIgnoreCase(word))
return current;
current = currentIndexNode;
currentIndexNode = currentIndexNode.getLink();
} while (currentIndexNode != null);
}
return null;
}
public int totalWords()
{
Node current = front;
int totalWords = 0;
while (current != null)
{
totalWords += current.getCount();
current = current.getLink();
}
return totalWords;
}
public int totalUniqueWords()
{
Node current = front;
int totalUniqueWords = 0;
while (current != null)
{
totalUniqueWords++;
current = current.getLink();
}
return totalUniqueWords;
}
public int totalNumOfComparisons()
{
return numOfComparisons;
}
public int totalNodeChanges()
{
return nodeChanges;
}
public String totalTimeElapsed()
{
if (timer == null)
return "This is an untimed list";
DecimalFormat threePlaces = new DecimalFormat("#0.000");
return threePlaces.format((System.nanoTime() - timer) * Math.pow(10, -9)) + " seconds";
}
public void plusComparisons()
{
numOfComparisons++;
}
public void plusNodeChanges()
{
nodeChanges++;
}
protected Node sameWord(Node input)
{
Node current = front;
while (current != null)
{
if (current.getWord().equalsIgnoreCase(input.getWord()))
return current;
current = current.getLink();
}
return null;
}
}
Node.java
public class Node
{
private Node link;
private String word;
private int count = 1;
private int index = -1;
public Node(String word)
{
this.word = word;
}
public Node getLink()
{
return link;
}
public String getWord()
{
return word;
}
public int getCount()
{
return count;
}
public int getIndex()
{
return index;
}
public void setLink(Node input)
{
link = input;
}
public void setWord(String input)
{
word = input;
}
public void setCount(int input)
{
count = input;
}
public void setIndex(int input)
{
index = input;
}
public void plusCount()
{
count++;
}
public void plusIndex()
{
index++;
}
public void minusIndex()
{
index--;
}
public boolean isEqual(Node input)
{
if (input.getWord().equalsIgnoreCase(this.word))
return true;
return false;
}
}
运行 SelfAdjustingListOne 的代码
public static SelfAdjustingListOne salo;
public static void main(String[] args)
{
System.out.println("Running fifth pass...");
System.out.println("Time to execute fifth pass: " + pass5());
}
public static String pass5()
{
salo = new SelfAdjustingListOne(System.nanoTime());
try
{
Scanner scanner = new Scanner(new File(fileDirectory + fileNames[0] + fileExtension));
while (scanner.hasNext())
{
String s = scanner.next();
s.replaceAll("^[^a-zA-Z0-9]+", "");
s.replaceAll("[^a-zA-Z0-9]+$", "");
if (s.length() == 1 || s.length() == 0)
{
if (!Character.isAlphabetic(s.charAt(0)) && !Character.isDigit(s.charAt(0)))
continue;
}
salo.adjustingAdd(new Node(s));
}
scanner.close();
} catch (FileNotFoundException e)
{
System.out.println("No file found matching that name/directory");
}
return salo.totalTimeElapsed();
}
它说它正在读取的文件是 A Bee 电影脚本，由于帖子的最大长度，我无法发布，但任何文本文件都应该这样做。
【问题讨论】：
-
@samabcde 我很乐意提供一个例子，但我不太确定为什么会发生这种情况。我可以提供我的其余文件，以便重现问题。不幸的是，我无法创建一个会产生此问题的测试用例，因为我不知道它为什么会发生，这就是我在这里的原因。
-
没有更多细节很难判断发生了什么，尝试在暂停代码之前添加断点并逐步运行以查看发生了什么you may reference this。由于您怀疑 while 循环正在暂停，请同时发布相关代码。
-
@samabcde 我会在业余时间尝试再次进行断点调试，但这就是我最初的问题所在。调试是 Eclipse 决定在没有警告的情况下挂起自己。如果您愿意，我发布了所有相关代码。感谢您迄今为止的关注和帮助。
-
类
Node是来自库还是您制作的自定义类？我需要这个类来编译。
标签： java eclipse debugging linked-list