java.util.NoSuchElementException 在 java 中使用迭代器

问题描述

我正在尝试使用迭代器对我的日志列表进行迭代.目标是搜索包含与新日志相同的电话号码、类型和日期的日志

I'm trying to iterate through a list using the iterator over my list of Logs. The goal is to search for a logs which contains the same phonenumber, type and date as the new log

但是，我的条件语句中出现 java.util.NoSuchElementException.有谁知道可能导致问题的原因?

However, I get a java.util.NoSuchElementException in my conditional statement. Does anyone know what might cause the problem?

我的代码

public void addLog(String phonenumber, String type, long date, int incoming, int outgoing)
{
    //Check if log exists or else create it.
    Log newLog = new Log(phonenumber, type, date, incoming, outgoing);

    //Log exists
    Boolean notExist = false;

    //Iterator loop
    Iterator<Log> iterator = logs.iterator();


    while (iterator.hasNext())
    {
        //This is where get the exception
        if (iterator.next().getPhonenumber() == phonenumber  && iterator.next().getType() == type && iterator.next().getDate() == date)
        {

            updateLog(newLog, iterator.next().getId());
        }
        else
        {   
            notExist = true;
        }

    }

    if (notExist)
    {
        logs.add(newLog);
    }

}

推荐答案

你在一次迭代中多次调用 next() 迫使 Iterator 移动到一个不存在的元素.

You are calling next() a bunch of times in one iteration forcing the Iterator to move to an element that doesn't exist.

代替

if (iterator.next().getPhonenumber() == phonenumber  && iterator.next().getType() == type && iterator.next().getDate() == date)
{
    updateLog(newLog, iterator.next().getId());
    ...

使用

Log log = iterator.next();

if (log.getPhonenumber() == phonenumber  && log.getType() == type && log.getDate() == date)
{
    updateLog(newLog, log .getId());
    ...

每次调用 Iterator#next() 时，它都会向前移动底层光标.

Every time you call Iterator#next(), it moves the underlying cursor forward.

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