No idea what the validator is looking for here.

Question about the task

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So I've tried the following: 1) I fixed isLastDateInDates() so that it compares the getTime() values rather than the object hashcodes. It now returns true. I left updateLastDate as is, as it should change the variable last date to the updated one. Validator won't accept the last 2 conditions. 2) I made an iterator in updateLastDate so that I could "remove" the object instead of just changing its value. Then I added a new value to the set with the updated time. Validator didn't like it. 3) I wondered if they wanted this to always work no matter how many new dates were added, so I changed the dates HashSet to a TreeSet and iterated through it to set the last element to lastDate. This way, if a new more recent date was added, all the other functions should work on that Date object instead of just hardcoding one of them. The validator didn't like this either. Am I misunderstanding the problem? Is there another option I haven't considered yet? (my code reflects #3 above)

Historians added several dates of past events to a special set in the initializeDates method. Later, they studied the historical documents more closely and more precisely calculated the time of the latest event lastDate. But what was their surprise when they found that the required date wasn't in the set. In other words, the isLastDateInDates method returns false.
Amigo, your duty is to save history. Make the changes necessary to ensure that the date of the last event is in the dates set (i.e. the program returns true).

Requirements:

The Solution class must have a private Set<Date> dates field.
The Solution class must have a private Date lastDate field.
The isLastDateInDates method must correctly return a boolean indicating whether lastDate is in dates.
The number of elements in the dates set must not change after calling the updateLastDate method.
The updateLastDate method must remove the old lastDate element from the dates set.
The updateLastDate method must add the updated lastDate date to the dates set.

package com.codegym.task.task36.task3612; import java.util.*; /* Why doesn't the set contain an element? */ public class Solution { private Set<Date> dates; private Date lastDate; public static void main(String[] args) { Solution solution = new Solution(); solution.initializeDates(); solution.updateLastDate(3_600_000L); System.out.println(solution.isLastDateInDates()); } public boolean isLastDateInDates() { for (Date currentDate : dates) { if (currentDate.getTime() == lastDate.getTime()) { return true; } } return false; } private void initializeDates() { dates = new TreeSet<Date>(); dates.add(new Date(9999999L)); dates.add(new Date(2222222L)); dates.add(new Date(3333333L)); dates.add(new Date(4444444L)); dates.add(new Date(5555555L)); Iterator<Date> iterator = dates.iterator(); while (iterator.hasNext()) { lastDate = iterator.next(); } } protected void updateLastDate(long delta) { Iterator<Date> iter = dates.iterator(); Date oldLastDate = new Date(); while (iter.hasNext()) { Date currentDate = iter.next(); if (currentDate.getTime() == lastDate.getTime()) { oldLastDate = (Date) currentDate.clone(); iter.remove(); } } lastDate = oldLastDate; oldLastDate.setTime(oldLastDate.getTime() + delta); dates.add(lastDate); } }

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Teodor Clipa Backend Developer

4 September 2020, 22:09

solution

Reset your task and simply do what the requirements say; all I changed was the updateLastDate method as such:

protected void updateLastDate(long delta) {
        dates.remove(lastDate);
        lastDate.setTime(lastDate.getTime() + delta);
        dates.add(lastDate);
    }