Java map an array of Strings to an array of Integers

问题

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.

回答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);

回答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));

来源：https://stackoverflow.com/questions/43877296/java-map-an-array-of-strings-to-an-array-of-integers