collections Archives - Page 2 of 12

Sort a list from another list IDs

I have a list with some identifiers like this: List<long> docIds = new List<long>() { 6, 1, 4, 7, 2 }; Morover, I … Read more

How can I convert int[] to Integer[] in Java?

by IT Nursery

I’m new to Java and very confused. I have a large dataset of length 4 int[] and I want to count the number … Read more

Recreating a Dictionary from an IEnumerable

by IT Nursery

I have a method that returns an IEnumerable<KeyValuePair<string, ArrayList>>, but some of the callers require the result of the method to be a … Read more

What Java 8 Stream.collect equivalents are available in the standard Kotlin library?

by IT Nursery

In Java 8, there is Stream.collect which allows aggregations on collections. In Kotlin, this does not exist in the same way, other than … Read more

Convert Enumeration to a Set/List

by IT Nursery

Is there some one-liner bridge method to dump a given Enumeration to java.util.List or java.util.Set? Something built-in like Arrays.asList() or Collection.toArray() should exist … Read more

Properly removing an Integer from a List

by IT Nursery

Here’s a nice pitfall I just encountered. Consider a list of integers: List<Integer> list = new ArrayList<Integer>(); list.add(5); list.add(6); list.add(7); list.add(1); Any educated … Read more

How can I loop through a List and grab each item?

by IT Nursery

How can I loop through a List and grab each item? I want the output to look like this: Console.WriteLine(“amount is {0}, and … Read more

Which is more efficient, a for-each loop, or an iterator?

by IT Nursery

Which is the most efficient way to traverse a collection? List<Integer> a = new ArrayList<Integer>(); for (Integer integer : a) { integer.toString(); } … Read more