Dmitry Roo

var stringIntegerMap = Map.of("1", 1,
                "2", 2,
                "3", 3);

        var max = stringIntegerMap.entrySet().stream()
                .max(Map.Entry.comparingByValue())
                .orElseThrow();

        System.out.println(max.getKey());
        System.out.println(max.getValue());

var s = "от 124 871 до 252 676 уе";

        var pattern = Pattern.compile("от (?<from>[0-9\\s]*) до (?<to>[0-9\\s]*) уе");
        var matcher = pattern.matcher(s);

        if (matcher.find()) {
            System.out.println(matcher.group("from"));
            System.out.println(matcher.group("to"));
        }

var productListWithUrlName = new ArrayList<Product>();
        var productListWithPrice = new ArrayList<Product>();

        var mergedProducts = Stream.concat(productListWithPrice.stream(), productListWithUrlName.stream())  // Объединяем коллекции
                .collect(Collectors.toMap(Product::id, Function.identity(), (product1, product2) -> mergeProducts(product1, product2)));

private Product mergeProducts(Product product1, Product product2) {
        // TODO :: реализовать объединение двух Product
    }

import java.util.*;
import java.util.stream.Collectors;
import java.util.stream.IntStream;
import java.util.stream.Stream;

class Scratch {

    public static void main(String[] args) {
        int[] ints = new int[]{13, 24, 24, 65, 3, 32, 27, 77, 88, 25, 74, 14};

        batches(Arrays.stream(ints).boxed().toList(), 3)
                .map(list -> list.stream().map(String::valueOf).collect(Collectors.joining(" ")))
                .reduce((s1, s2) -> s1 + System.lineSeparator() + s2)
                .ifPresent(System.out::println);
    }

    private static <T> Stream<List<T>> batches(List<T> source, int length) {
        var size = source.size();
        if (length <= 0 || size <= 0) {
            return Stream.empty();
        }
        var fullChunks = (size - 1) / length;
        return IntStream.range(0, fullChunks + 1).mapToObj(
                n -> source.subList(n * length, n == fullChunks ? size : (n + 1) * length));
    }
}

var intArray = new int[]{1, 2, 3};

var string = Arrays.stream(intArray)  // преобразуем массив в IntStream
                .boxed() // преоборазуем IntStream в Stream<Integer>
                .map(String::valueOf) // Integer -> String
                .collect(Collectors.joining(" ")); // собираем в строку с разделителем " "