eugenp · theangrydev · May 4, 2024 · Apr 20, 2024 · Apr 27, 2024 · Apr 30, 2024
diff --git a/core-java-modules/core-java-collections-maps-8/pom.xml b/core-java-modules/core-java-collections-maps-8/pom.xml
@@ -13,6 +13,24 @@
         <version>0.0.1-SNAPSHOT</version>
     </parent>
 
+    <dependencies>
+        <dependency>
+            <groupId>com.fasterxml.jackson.core</groupId>
+            <artifactId>jackson-databind</artifactId>
+            <version>${jackson.version}</version>
+        </dependency>
+        <dependency>
+            <groupId>com.google.code.gson</groupId>
+            <artifactId>gson</artifactId>
+            <version>${gson.version}</version>
+        </dependency>
+        <dependency>
+            <groupId>commons-beanutils</groupId>
+            <artifactId>commons-beanutils</artifactId>
+            <version>${beanutils.version}</version>
+        </dependency>
+    </dependencies>
+
     <build>
         <plugins>
             <plugin>
@@ -26,4 +44,11 @@
             </plugin>
         </plugins>
     </build>
+
+    <properties>
+        <gson.version>2.10.1</gson.version>
+        <jackson.version>2.17.0</jackson.version>
+        <beanutils.version>1.9.4</beanutils.version>
+    </properties>
+
 </project>
diff --git a/...re-java-collections-maps-8/src/main/java/com/baeldung/map/castingmaptoobject/Address.java b/...re-java-collections-maps-8/src/main/java/com/baeldung/map/castingmaptoobject/Address.java
@@ -0,0 +1,43 @@
+package com.baeldung.map.castingmaptoobject;
+
+public class Address {
+    private String city;
+    private Country country;
+
+    public Address() {
+        // default constructor needed for Jackson deserialization
+    }
+
+    public Address(String city, Country country) {
+        this.city = city;
+        this.country = country;
+    }
+
+    public Country getCountry() {
+        return country;
+    }
+
+    public void setCountry(Country country) {
+        this.country = country;
+    }
+
+    public String getCity() {
+        return city;
+    }
+
+    public void setCity(String city) {
+        this.city = city;
+    }
+
+    @Override
+    public boolean equals(Object o) {
+        if (this == o) return true;
+        if (o == null || getClass() != o.getClass()) return false;
+
+        Address address = (Address) o;
+
+        if (!city.equals(address.city)) return false;
+        return country.getName().equals(address.country.getName());
+    }
+
+}
diff --git a/...re-java-collections-maps-8/src/main/java/com/baeldung/map/castingmaptoobject/Country.java b/...re-java-collections-maps-8/src/main/java/com/baeldung/map/castingmaptoobject/Country.java
@@ -0,0 +1,21 @@
+package com.baeldung.map.castingmaptoobject;
+
+public class Country {
+    private String name;
+
+    public Country() {
+        // default constructor needed for Jackson deserialization
+    }
+
+    public Country(String name) {
+        this.name = name;
+    }
+
+    public String getName() {
+        return name;
+    }
+
+    public void setName(String name) {
+        this.name = name;
+    }
+}
diff --git a/.../core-java-collections-maps-8/src/main/java/com/baeldung/map/castingmaptoobject/User.java b/.../core-java-collections-maps-8/src/main/java/com/baeldung/map/castingmaptoobject/User.java
@@ -0,0 +1,33 @@
+package com.baeldung.map.castingmaptoobject;
+
+import java.util.List;
+
+public class User {
+    private Long id;
+    private String name;
+    private List<Address> addresses;
+
+    public Long getId() {
+        return id;
+    }
+
+    public void setId(Long id) {
+        this.id = id;
+    }
+
+    public String getName() {
+        return name;
+    }
+
+    public void setName(String name) {
+        this.name = name;
+    }
+
+    public List<Address> getAddresses() {
+        return addresses;
+    }
+
+    public void setAddresses(List<Address> addresses) {
+        this.addresses = addresses;
+    }
+}
diff --git a/...-maps-8/src/test/java/com/baeldung/map/castingmaptoobject/CastingMapToObjectUnitTest.java b/...-maps-8/src/test/java/com/baeldung/map/castingmaptoobject/CastingMapToObjectUnitTest.java
@@ -0,0 +1,86 @@
+package com.baeldung.map.castingmaptoobject;
+
+import com.fasterxml.jackson.databind.DeserializationFeature;
+import com.fasterxml.jackson.databind.ObjectMapper;
+import com.google.gson.Gson;
+import org.apache.commons.beanutils.BeanUtils;
+import org.junit.jupiter.api.Test;
+
+import java.lang.reflect.InvocationTargetException;
+import java.util.HashMap;
+import java.util.List;
+import java.util.Map;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertThrows;
+
+public class CastingMapToObjectUnitTest {
+
+    private static final Map<String, Object> map = Map.of(
+        "id", 1L,
+        "name", "Baeldung",
+        "addresses", List.of(
+            new Address("La Havana", new Country("Cuba")),
+            new Address("Paris", new Country("France"))
+        )
+    );
+
+    @Test
+    void givenMap_whenCasting_thenThrow() {
+        assertThrows(ClassCastException.class, () -> { User user = (User) map; });
+    }
+
+    @Test
+    void givenMap_whenUsingBeanUtils_thenConvertToObject() throws InvocationTargetException, IllegalAccessException {
+        User user = new User();
+        BeanUtils.populate(user, map);
+
+        assertEqualsMapAndUser(map, user);
+    }
+
+    @Test
+    void givenMap_whenUsingJackson_thenConvertToObject() {
+        ObjectMapper objectMapper = new ObjectMapper();
+        User user = objectMapper.convertValue(map, User.class);
+
+        assertEqualsMapAndUser(map, user);
+    }
+
+    @Test
+    void givenMap_whenUsingJacksonWithWrongAttrs_thenThrow() {
+        Map<String, Object> modifiedMap = new HashMap<>(map);
+        modifiedMap.put("enabled", true);
+
+        ObjectMapper objectMapper = new ObjectMapper();
+
+        assertThrows(IllegalArgumentException.class, () -> objectMapper.convertValue(modifiedMap, User.class));
+    }
+
+    @Test
+    void givenMap_whenUsingJacksonIgnoreUnknownProps_thenConvertToObject() {
+        Map<String, Object> modifiedMap = new HashMap<>(map);
+        modifiedMap.put("enabled", true);
+
+        ObjectMapper objectMapper = new ObjectMapper();
+        objectMapper.configure(DeserializationFeature.FAIL_ON_UNKNOWN_PROPERTIES, false);
+        User user = objectMapper.convertValue(modifiedMap, User.class);
+
+        assertEqualsMapAndUser(modifiedMap, user);
+    }
+
+    @Test
+    void givenMap_whenUsingGson_thenConvertToObject() {
+        Gson gson = new Gson();
+        String jsonMap = gson.toJson(map);
+        User user = gson.fromJson(jsonMap, User.class);
+
+        assertEqualsMapAndUser(map, user);
+    }
+
+    private static void assertEqualsMapAndUser(Map<String, Object> map, User user) {
+        assertEquals(map.get("id"), user.getId());
+        assertEquals(map.get("name"), user.getName());
+        assertEquals(map.get("addresses"), user.getAddresses());
+    }
+
+}