BAEL-2480 Java Map to String conversion (#6075)

* BAEL-2480 Java Map to String conversion

* BAEL-2480 Java Map to String conversion

* BAEL-2480 Java Map to String conversion

* BAEL-2480 Java Map to String conversion

java-collections-maps/src/main/java/com/baeldung/convert/MapToString.java

@@ -0,0 +1,34 @@
+package com.baeldung.convert;
+
+import com.google.common.base.Joiner;
+import org.apache.commons.lang3.StringUtils;
+
+import java.util.Map;
+import java.util.stream.Collectors;
+
+public class MapToString {
+
+    public static String convertWithIteration(Map<Integer, ?> map) {
+        StringBuilder mapAsString = new StringBuilder("{");
+        for (Integer key : map.keySet()) {
+            mapAsString.append(key + "=" + map.get(key) + ", ");
+        }
+        mapAsString.delete(mapAsString.length()-2, mapAsString.length()).append("}");
+        return mapAsString.toString();
+    }
+
+    public static String convertWithStream(Map<Integer, ?> map) {
+        String mapAsString = map.keySet().stream()
+                .map(key -> key + "=" + map.get(key))
+                .collect(Collectors.joining(", ", "{", "}"));
+        return mapAsString;
+    }
+
+    public static String convertWithGuava(Map<Integer, ?> map) {
+        return Joiner.on(",").withKeyValueSeparator("=").join(map);
+    }
+
+    public static String convertWithApache(Map map) {
+        return StringUtils.join(map);
+    }
+}

java-collections-maps/src/main/java/com/baeldung/convert/StringToMap.java

@@ -0,0 +1,21 @@
+package com.baeldung.convert;
+
+import com.google.common.base.Splitter;
+
+import java.util.Arrays;
+import java.util.Map;
+import java.util.stream.Collectors;
+
+public class StringToMap {
+
+    public static Map<String, String> convertWithStream(String mapAsString) {
+        Map<String, String> map = Arrays.stream(mapAsString.split(","))
+                .map(entry -> entry.split("="))
+                .collect(Collectors.toMap(entry -> entry[0], entry -> entry[1]));
+        return map;
+    }
+
+    public static Map<String, String> convertWithGuava(String mapAsString) {
+        return Splitter.on(',').withKeyValueSeparator('=').split(mapAsString);
+    }
+}

java-collections-maps/src/test/java/com/baeldung/convert/MapToStringUnitTest.java

@@ -0,0 +1,48 @@
+package com.baeldung.convert;
+
+import org.apache.commons.collections4.MapUtils;
+import org.junit.Assert;
+import org.junit.jupiter.api.BeforeEach;
+import org.junit.jupiter.api.Test;
+
+import java.util.HashMap;
+import java.util.Map;
+
+public class MapToStringUnitTest {
+
+    private Map<Integer, String> wordsByKey = new HashMap<>();
+
+    @BeforeEach
+    public void setup() {
+        wordsByKey.clear();
+        wordsByKey.put(1, "one");
+        wordsByKey.put(2, "two");
+        wordsByKey.put(3, "three");
+        wordsByKey.put(4, "four");
+    }
+
+    @Test
+    public void givenMap_WhenUsingIteration_ThenResultingMapIsCorrect() {
+        String mapAsString = MapToString.convertWithIteration(wordsByKey);
+        Assert.assertEquals("{1=one, 2=two, 3=three, 4=four}", mapAsString);
+    }
+
+    @Test
+    public void givenMap_WhenUsingStream_ThenResultingMapIsCorrect() {
+        String mapAsString = MapToString.convertWithStream(wordsByKey);
+        Assert.assertEquals("{1=one, 2=two, 3=three, 4=four}", mapAsString);
+    }
+
+    @Test
+    public void givenMap_WhenUsingGuava_ThenResultingMapIsCorrect() {
+        String mapAsString = MapToString.convertWithGuava(wordsByKey);
+        Assert.assertEquals("1=one,2=two,3=three,4=four", mapAsString);
+    }
+
+    @Test
+    public void givenMap_WhenUsingApache_ThenResultingMapIsCorrect() {
+        String mapAsString = MapToString.convertWithApache(wordsByKey);
+        Assert.assertEquals("{1=one, 2=two, 3=three, 4=four}", mapAsString);
+        MapUtils.debugPrint(System.out, "Map as String", wordsByKey);
+    }
+}

java-collections-maps/src/test/java/com/baeldung/convert/StringToMapUnitTest.java

@@ -0,0 +1,23 @@
+package com.baeldung.convert;
+
+import org.junit.Assert;
+import org.junit.jupiter.api.Test;
+
+import java.util.Map;
+
+public class StringToMapUnitTest {
+
+    @Test
+    public void givenString_WhenUsingStream_ThenResultingStringIsCorrect() {
+        Map<String, String> wordsByKey = StringToMap.convertWithStream("1=one,2=two,3=three,4=four");
+        Assert.assertEquals(4, wordsByKey.size());
+        Assert.assertEquals("one", wordsByKey.get("1"));
+    }
+
+    @Test
+    void givenString_WhenUsingGuava_ThenResultingStringIsCorrect() {
+        Map<String, String> wordsByKey = StringToMap.convertWithGuava("1=one,2=two,3=three,4=four");
+        Assert.assertEquals(4, wordsByKey.size());
+        Assert.assertEquals("one", wordsByKey.get("1"));
+    }
+}