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How do I convert int[] into List<Integer> in Java?
Of course, I'm interested in any other answer than doing it in a loop, item by item. But if there's no other answer, I'll pick that one as the best to show the fact that this functionality is not part of Java.
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Since int[] is a class, it can be used to declare variables. For example, int[] list; creates a variable named list of type int[].
An array can be converted to an ArrayList using the following methods: Using ArrayList. add() method to manually add the array elements in the ArrayList: This method involves creating a new ArrayList and adding all of the elements of the given array to the newly created ArrayList using add() method.
We can use the Stream provided by Java 8 to convert a list of Integer to a primitive integer array in Java. We start by converting given List<Integer> to Stream<Integer> using List. stream() method. Now all we need to do is convert Stream<Integer> to int[] .
int array. Call either Arrays.stream or IntStream.of.IntStream#boxed to use boxing conversion from int primitive to Integer objects.Stream.collect( Collectors.toList() ). Or more simply in Java 16+, call Stream#toList().Example:
int[] ints = {1,2,3}; List<Integer> list = Arrays.stream(ints).boxed().collect(Collectors.toList()); In Java 16 and later:
List<Integer> list = Arrays.stream(ints).boxed().toList(); If you love us? You can donate to us via Paypal or buy me a coffee so we can maintain and grow! Thank you!
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