Java map an array of Strings to an array of Integers

Question

I found this code on SO to map strings to ints

Arrays.stream(myarray).mapToInt(Integer::parseInt).toArray();

But how do I make it map to Integer type not the primitive int?

I tried switching from Integer.parseInt to Integer.valueOf, but it seems that the mapToInt() method forces the primitive type.

I have an ArrayList of arrays of Integers, so I cannot use primitive ints.

Solution 1

Since String and Integer are both reference types you can simply call Stream::map to transform your array.

Integer[] boxed = Stream.of(myarray).map(Integer::valueOf).toArray(Integer[]::new);

Solution 2

you can use the Stream<Integer> boxed() method.

Stream<Integer> boxed() returns a Stream consisting of the elements of this stream, each boxed to an Integer.

ArrayList<Integer[]> resultSet = new ArrayList<>();
resultSet.add(Arrays.stream(myarray).mapToInt(Integer::parseInt).boxed().toArray(Integer[]::new));

Comments

[Alfabravo]

This question seems relevant to your doubt.

[Fiodor]

Thanks a lot. Is there a way to do it more elegantly, though? Like for example in JavaScript myarray.map(function(e) {return parseInt(e);});? It seems like a lot of nested calls and intermediate types for just a simple String[] to Integer[] conversion.

[Teena George]

You can map instead of boxing and mapInt: String [] myArray = {"1", "2", "3", "4"}; Integer[] integerList =Arrays.stream(myArray).map(Integer::valueOf).toArray(Intege‌​r[]::new); System.out.print(integerList[0].getClass()); //output: class java.lang.Integer