So I have a list of objects. Suppose they have 2 fields startDate, endDate(data type is timestamp). So if startDate is equal to startDate of another object then I have to choose the object with higher endDate. How can I achieve this efficiently. I can use 2 for loops but that would have a high time complexity. Any better way of doing it? Thanks
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Answer
Stream over your list, collect to map using your objects startdate as key and use a merging function to decide to which object to map if two or more objects have the same startdate by comparing the enddates. Something like:
Collection<YourObject> result = yourList.stream() .collect(Collectors.toMap(YourObject::getStartDate, Function.identity(), (a, b) -> a.getEndDate().after(b.getEndDate()) ? a : b)) .values();