From e7f1416a0f007432f340f335c41606b3d9444b6c Mon Sep 17 00:00:00 2001
From: Falmer <foulorown@gmail.com>
Date: Mon, 26 Jan 2026 12:32:57 +0300
Subject: [PATCH] Add WordFrequencyImpl

---
 .../ru/ilug/c10_word_frequency/MainTest.java  |  2 +-
 .../c10_word_frequency/WordFrequencyImpl.java | 30 +++++++++++++++++++
 2 files changed, 31 insertions(+), 1 deletion(-)
 create mode 100644 src/main/java/ru/ilug/c10_word_frequency/WordFrequencyImpl.java

diff --git a/src/main/java/ru/ilug/c10_word_frequency/MainTest.java b/src/main/java/ru/ilug/c10_word_frequency/MainTest.java
index 4054e22..606cbb3 100644
--- a/src/main/java/ru/ilug/c10_word_frequency/MainTest.java
+++ b/src/main/java/ru/ilug/c10_word_frequency/MainTest.java
@@ -9,7 +9,7 @@ import java.util.Map;
 public class MainTest {
 
     public static void main(String[] args) {
-        WordFrequency wordFrequency = null;
+        WordFrequency wordFrequency = new WordFrequencyImpl();
 
         List<String> words1 = List.of("list", "map", "class", "public", "list", "set", "word", "class", "list", "public", "main", "string", "map");
         List<String> words2 = List.of("long", "string", "list", "public", "import", "double", "word", "map", "class", "package", "void", "long");
diff --git a/src/main/java/ru/ilug/c10_word_frequency/WordFrequencyImpl.java b/src/main/java/ru/ilug/c10_word_frequency/WordFrequencyImpl.java
new file mode 100644
index 0000000..95a87a7
--- /dev/null
+++ b/src/main/java/ru/ilug/c10_word_frequency/WordFrequencyImpl.java
@@ -0,0 +1,30 @@
+package ru.ilug.c10_word_frequency;
+
+import lombok.extern.slf4j.Slf4j;
+
+import java.util.*;
+import java.util.stream.Collectors;
+import java.util.stream.Stream;
+
+@Slf4j
+public class WordFrequencyImpl implements WordFrequency {
+
+    /**
+     * Ищет слова, которые встречаются в обоих списках, считает суммарную частоту каждого
+     * @param list1 Первый список слов
+     * @param list2 Второй список слов
+     * @return Частота слов, которые есть в обоих списках
+     */
+    @Override
+    public Map<String, Integer> getWordFrequency(List<String> list1, List<String> list2) {
+        Set<String> retainedSet = new HashSet<>(list1);
+        retainedSet.retainAll(list2);
+
+        return Stream.concat(list1.stream(), list2.stream())
+                .filter(retainedSet::contains)
+                .collect(Collectors.groupingBy(w -> w, Collectors.collectingAndThen(
+                        Collectors.toList(),
+                        List::size
+                )));
+    }
+}