Ivan C Ivan C - 23 days ago 13
Java Question

Sorting a list with stream.sorted() in Java

I'm interested in sorting a list from a stream. This is the code I'm using:

list.stream().sorted((o1, o2)->o1.getItem().getValue().compareTo(o2.getItem().getValue()))
.collect(Collectors.toList());


Am I missing something? The list is not sorting.

It should sort the lists according to the item with the lowest value.

for (int i = 0; i < list.size(); i++)
{
System.out.println("list " + (i+1));
print(list, i);
}


And the print method:

public static void print(List<List> list, int i)
{
System.out.println(list.get(i).getItem().getValue())
}

Answer

This is not like Collections.sort() where the parameter reference gets sorted. In this case you just get a sorted stream that you need to collect and assign to another variable eventually:

List result = list.stream().sorted((o1, o2)->o1.getItem().getValue().
                                   compareTo(o2.getItem().getValue())).
                                   collect(Collectors.toList());

You've just missed to assign the result :)

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