Convert Map To MultiValueMap (eugenp#16703)

* Convert Map To MultiValueMap * Convert Map To MultiValueMap --------- Co-authored-by: Neetika Khandelwal <[email protected]>
SmartyAnsh · Jun 6, 2024 · 0cd7cad · 0cd7cad
1 parent 7ba3a2e
commit 0cd7cad
Showing 1 changed file with 61 additions and 0 deletions.
diff --git a/spring-core-4/src/test/java/com/baeldung/maptomultivaluemap/MapToMultiValueMapUnitTest.java b/spring-core-4/src/test/java/com/baeldung/maptomultivaluemap/MapToMultiValueMapUnitTest.java
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+package com.baeldung.maptomultivaluemap;
+
+import java.util.Arrays;
+import java.util.HashMap;
+import java.util.List;
+import java.util.Map;
+import java.util.stream.Collectors;
+
+import org.junit.jupiter.api.Test;
+import org.springframework.util.CollectionUtils;
+import org.springframework.util.LinkedMultiValueMap;
+import org.springframework.util.MultiValueMap;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+
+public class MapToMultiValueMapUnitTest {
+
+    @Test
+    public void givenMap_whenConvertToMultiValueMapUsingIteration_thenCountEntries() {
+
+        Map<String, List<String>> map = new HashMap<>();
+        map.put("rollNo", Arrays.asList("4", "2", "7", "3"));
+        map.put("name", Arrays.asList("John", "Alex", "Maria", "Jack"));
+        map.put("hobbies", Arrays.asList("Badminton", "Reading novels", "Painting", "Cycling"));
+
+        MultiValueMap<String, String> multiValueMap = new LinkedMultiValueMap<>();
+        for (Map.Entry<String, List<String>> entry : map.entrySet()) {
+            multiValueMap.put(entry.getKey(), entry.getValue());
+        }
+
+        assertEquals(3, multiValueMap.size());
+    }
+
+    @Test
+    public void givenMap_whenConvertToMultiValueMapUsingCollections_thenCountEntries() {
+
+        Map<String, List<String>> map = new HashMap<>();
+        map.put("rollNo", Arrays.asList("4", "2", "7", "3"));
+        map.put("name", Arrays.asList("John", "Alex", "Maria", "Jack"));
+        map.put("hobbies", Arrays.asList("Badminton", "Reading novels", "Painting", "Cycling"));
+
+        MultiValueMap<String, String> multiValueMap = CollectionUtils.toMultiValueMap(map);
+
+        assertEquals(3, multiValueMap.size());
+    }
+
+    @Test
+    public void givenMap_whenConvertToMultiValueMapUsingStreams_thenCountEntries() {
+
+        Map<String, List<String>> map = new HashMap<>();
+        map.put("rollNo", Arrays.asList("4", "2", "7", "3"));
+        map.put("name", Arrays.asList("John", "Alex", "Maria", "Jack"));
+        map.put("hobbies", Arrays.asList("Badminton", "Reading novels", "Painting", "Cycling"));
+
+        MultiValueMap<String, String> multiValueMap = map.entrySet()
+            .stream()
+            .collect(Collectors.toMap(Map.Entry::getKey, Map.Entry::getValue, (oldValue, newValue) -> oldValue, LinkedMultiValueMap::new));
+
+        assertEquals(3, multiValueMap.size());
+    }
+}