BAEL-6692 - converting json to map and comparing (eugenp#14630)

* BAEL-6692 - converting json to map and comparing

* BAEL-6692 - converting json to map and comparing

* BAEL-6692 - converting json to map and comparing

json-modules/json-conversion/pom.xml

@@ -29,11 +29,17 @@
             <artifactId>jackson-databind</artifactId>
             <version>${jackson.version}</version>
         </dependency>
+        <dependency>
+            <groupId>com.google.guava</groupId>
+            <artifactId>guava</artifactId>
+            <version>${guava.version}</version>
+        </dependency>
     </dependencies>
 
     <properties>
         <json.version>20211205</json.version>
         <gson.version>2.10.1</gson.version>
+        <guava.version>32.1.2-jre</guava.version>
     </properties>
 
 </project>

json-modules/json-conversion/src/main/java/com/baeldung/jsontomap/FlattenUtils.java

@@ -0,0 +1,36 @@
+package com.baeldung.jsontomap;
+
+import java.util.HashMap;
+import java.util.List;
+import java.util.Map;
+
+public class FlattenUtils {
+    public static Map<String, Object> flatten(Map<String, Object> map) {
+        return flatten(map, null);
+    }
+
+    private static Map<String, Object> flatten(Map<String, Object> map, String prefix) {
+        Map<String, Object> flatMap = new HashMap<>();
+        map.forEach((key, value) -> {
+            String newKey = prefix != null ? prefix + "." + key : key;
+            if (value instanceof Map) {
+                flatMap.putAll(flatten((Map<String, Object>) value, newKey));
+            } else if (value instanceof List) {
+                // check for list of primitives
+                Object element = ((List<?>) value).get(0);
+                if (element instanceof String || element instanceof Number || element instanceof Boolean) {
+                    flatMap.put(newKey, value);
+                } else {
+                    // check for list of objects
+                    List<Map<String, Object>> list = (List<Map<String, Object>>) value;
+                    for (int i = 0; i < list.size(); i++) {
+                        flatMap.putAll(flatten(list.get(i), newKey + "[" + i + "]"));
+                    }
+                }
+            } else {
+                flatMap.put(newKey, value);
+            }
+        });
+        return flatMap;
+    }
+}

json-modules/json-conversion/src/main/java/com/baeldung/jsontomap/JsonUtils.java

@@ -0,0 +1,23 @@
+package com.baeldung.jsontomap;
+
+import com.fasterxml.jackson.core.type.TypeReference;
+import com.fasterxml.jackson.databind.ObjectMapper;
+import com.google.gson.Gson;
+import com.google.gson.reflect.TypeToken;
+
+import java.io.File;
+import java.io.FileReader;
+import java.io.IOException;
+import java.util.Map;
+
+public class JsonUtils {
+    public static Map<String, Object> jsonFileToMap(String path) throws IOException {
+        ObjectMapper mapper = new ObjectMapper();
+        return mapper.readValue(new File(path), new TypeReference<Map<String, Object>>() {});
+    }
+
+    public static Map<String, Object> jsonFileToMapGson(String path) throws IOException {
+        Gson gson = new Gson();
+        return gson.fromJson(new FileReader(path), new TypeToken<Map<String, Object>>() {}.getType());
+    }
+}

json-modules/json-conversion/src/test/java/com/baeldung/jsontomap/JSONComparisonUnitTest.java

@@ -0,0 +1,37 @@
+package com.baeldung.jsontomap;
+
+import com.google.common.collect.MapDifference;
+import com.google.common.collect.Maps;
+import org.junit.jupiter.api.Test;
+
+import java.io.IOException;
+import java.util.Map;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+public class JSONComparisonUnitTest {
+
+    @Test
+    void givenTwoJsonFiles_whenCompared_thenTheyAreDifferent() throws IOException {
+        Map<String, Object> firstMap = JsonUtils.jsonFileToMap("src/test/resources/first.json");
+        Map<String, Object> secondMap = JsonUtils.jsonFileToMap("src/test/resources/second.json");
+
+        MapDifference<String, Object> difference = Maps.difference(firstMap, secondMap);
+        difference.entriesDiffering().forEach((key, value) -> {
+            System.out.println(key + ": " + value.leftValue() + " - " + value.rightValue());
+        });
+        assertThat(difference.areEqual()).isFalse();
+    }
+
+    @Test
+    void givenTwoJsonFiles_whenFlattenedAndCompared_thenTheyAreDifferent() throws IOException {
+        Map<String, Object> firstFlatMap = FlattenUtils.flatten(JsonUtils.jsonFileToMap("src/test/resources/first.json"));
+        Map<String, Object> secondFlatMap = FlattenUtils.flatten(JsonUtils.jsonFileToMap("src/test/resources/second.json"));
+
+        MapDifference<String, Object> difference = Maps.difference(firstFlatMap, secondFlatMap);
+        difference.entriesDiffering().forEach((key, value) -> {
+            System.out.println(key + ": " + value.leftValue() + " - " + value.rightValue());
+        });
+        assertThat(difference.areEqual()).isFalse();
+    }
+}

json-modules/json-conversion/src/test/resources/first.json

@@ -0,0 +1,22 @@
+{
+  "name": "John",
+  "age": 30,
+  "cars": [
+    "Ford",
+    "BMW"
+  ],
+  "address": {
+    "street": "Second Street",
+    "city": "New York"
+  },
+  "children": [
+    {
+      "name": "Sara",
+      "age": 5
+    },
+    {
+      "name": "Alex",
+      "age": 3
+    }
+  ]
+}

json-modules/json-conversion/src/test/resources/second.json

@@ -0,0 +1,22 @@
+{
+  "name": "John",
+  "age": 30,
+  "cars": [
+    "Ford",
+    "Audi"
+  ],
+  "address": {
+    "street": "Main Street",
+    "city": "New York"
+  },
+  "children": [
+    {
+      "name": "Peter",
+      "age": 5
+    },
+    {
+      "name": "Cathy",
+      "age": 10
+    }
+  ]
+}