Question

这是基本课程：Issue(priority, description) 我有一个链表实现如下：

public class IssueQueue {
    public Issue issue;
    public IssueQueue next;

    private static int count = 0;

    public IssueQueue() {
    }

    public IssueQueue(Issue i) {
      issue = i;
      next = null;
    }

  public int getCount() {
      return count;
  }

  public void Add(Issue newIssue) {
      IssueQueue tempQ = this;
      IssueQueue newIssueQ = new IssueQueue(newIssue);
      if (count == 0) {
          issue = newIssue;
      } else if (issue.getPriority() > newIssue.getPriority()) {
          while (tempQ.next != null
                  && tempQ.issue.getPriority() >   newIssue.getPriority()) {
              tempQ = tempQ.next;
          }

        newIssueQ.next = tempQ.next;
        tempQ.next = newIssueQ;
    } else if (issue.getPriority() <= newIssue.getPriority()) {
        newIssueQ.issue = issue;
        newIssueQ.next = next;
        issue = newIssue;
        next = newIssueQ;

    }
    count++;
}

public void print() {
    IssueQueue tempQ = this;
    if (next == null) {
        System.out.println(issue);
    } else {
        do {
            System.out.println(tempQ.issue);
            tempQ = tempQ.next;
        } while (tempQ.next != null);
        System.out.println(tempQ.issue);
    }
    System.out.println("--------------------");
  }
}

问题在于，执行以下操作： iq.Add（新发行（10，“问题1”））; iq.print（）;

    iq.Add(new Issue(4, "Issue 2"));
    iq.print();

    iq.Add(new Issue(20, "Issue 3"));
    iq.print();

    iq.Add(new Issue(2, "Issue 4"));
    iq.print();

    iq.Add(new Issue(12, "Issue 5"));
    iq.print();

输出正确，直到第4次插入：

Issue[Priority: 20, Description: Issue 3]
Issue[Priority: 10, Description: Issue 1]
Issue[Priority: 4, Description: Issue 2]
Issue[Priority: 2, Description: Issue 4]

但是在第5次插入时，它变为：

Issue[Priority: 20, Description: Issue 3]
Issue[Priority: 10, Description: Issue 1]
Issue[Priority: 12, Description: Issue 5]
Issue[Priority: 4, Description: Issue 2]
Issue[Priority: 2, Description: Issue 4]

我的代码在哪里错了？

Answer 1

为什么不将Collections.sort()与您自己的优先级compareTo()一起使用？

您实际上是在要求我们使用调试器来执行您的代码。但这看起来很奇怪

 newIssueQ.next = tempQ.next;
 tempQ.next = newIssueQ;

看看你甚至没有检查所有优先事项。我理解这遍历了列表，但是...尝试单步调试，你会看到。

else if (issue.getPriority() > newIssue.getPriority()) {
          while (tempQ.next != null
                  && tempQ.issue.getPriority() >   newIssue.getPriority()) {
              tempQ = tempQ.next;
          }

Answer 2

根据此代码，您将在优先级较低的问题之后插入新问题。

while (tempQ.next != null
              && tempQ.issue.getPriority() >   newIssue.getPriority()) {
    tempQ = tempQ.next;
}

newIssueQ.next = tempQ.next;
tempQ.next = newIssueQ;

Answer 3

您应该将队列与控制逻辑分开。那么你不会因为你需要从内到外思考而感到困惑。我相信你很容易得到这个bug。

如果您无法遵循您的代码 - ＆gt;重构。

Answer 4

我建议你写一下

 PriorityQueue<Issue> issues =  new PriorityQueue<Issue>();

用Comparable实现Class Issue。

基于优先级的LinkedList插入问题

我的代码在哪里错了？

4 个答案: