Convert an Object to Map

Author: lokeshgupta1981

pom.xml

@@ -89,11 +89,36 @@
             <artifactId>jackson-databind</artifactId>
             <version>2.13.2.1</version>
         </dependency>
+        <dependency>
+            <groupId>com.fasterxml.jackson.datatype</groupId>
+            <artifactId>jackson-datatype-jsr310</artifactId>
+            <version>2.13.1</version>
+        </dependency>
+        <dependency>
+            <groupId>net.sf.dozer</groupId>
+            <artifactId>dozer</artifactId>
+            <version>5.5.1</version>
+        </dependency>
+        <dependency>
+            <groupId>io.craftsman</groupId>
+            <artifactId>dozer-jdk8-support</artifactId>
+            <version>1.0.6</version>
+        </dependency>
         <dependency>
             <groupId>com.fasterxml.jackson.dataformat</groupId>
             <artifactId>jackson-dataformat-xml</artifactId>
             <version>2.13.1</version>
         </dependency>
+        <dependency>
+            <groupId>com.fasterxml.jackson.dataformat</groupId>
+            <artifactId>jackson-dataformat-properties</artifactId>
+            <version>2.13.1</version>
+        </dependency>
+        <dependency>
+            <groupId>com.google.code.gson</groupId>
+            <artifactId>gson</artifactId>
+            <version>2.9.1</version>
+        </dependency>
         <dependency>
             <groupId>org.apache.commons</groupId>
             <artifactId>commons-compress</artifactId>

src/main/java/com/howtodoinjava/core/objectToMap/ConvertObjectToMapExample.java

@@ -0,0 +1,113 @@
+package com.howtodoinjava.core.objectToMap;
+
+import com.fasterxml.jackson.databind.ObjectMapper;
+import com.fasterxml.jackson.dataformat.javaprop.JavaPropsMapper;
+import com.fasterxml.jackson.datatype.jsr310.JavaTimeModule;
+import com.google.gson.Gson;
+import com.google.gson.GsonBuilder;
+import com.google.gson.JsonDeserializationContext;
+import com.google.gson.JsonDeserializer;
+import com.google.gson.JsonElement;
+import com.google.gson.JsonParseException;
+import com.google.gson.JsonPrimitive;
+import com.google.gson.JsonSerializationContext;
+import com.google.gson.JsonSerializer;
+import com.google.gson.reflect.TypeToken;
+import java.io.IOException;
+import java.lang.reflect.Field;
+import java.lang.reflect.Type;
+import java.text.SimpleDateFormat;
+import java.time.LocalDate;
+import java.time.format.DateTimeFormatter;
+import java.util.Arrays;
+import java.util.HashMap;
+import java.util.List;
+import java.util.Map;
+import java.util.Properties;
+import java.util.stream.Collectors;
+
+public class ConvertObjectToMapExample {
+
+  public static void main(String[] args) throws IOException {
+
+    Employee employee = new Employee(1, "Alex",
+        LocalDate.of(1995, 1, 2),
+        List.of("Delhi", "Nevada"),
+        List.of(new Role(11, "Finance"), new Role(12, "HR")));
+
+    Map<String, String> employeeMap;
+
+    employeeMap = convertObjectToMapUsingObjectMapper(employee);
+    System.out.println(employeeMap);
+
+    Properties employeeProperties = convertObjectToMapUsingJavaPropsMapper(employee);
+    System.out.println(employeeProperties);
+
+    employeeMap = convertObjectToMapUsingGson(employee);
+    System.out.println(employeeMap);
+
+    System.out.println(toKeyValuePairs(employee));
+  }
+
+  public static Map<String, Object> toKeyValuePairs(Object instance) {
+    return Arrays.stream(Employee.class.getDeclaredFields())
+        .collect(Collectors.toMap(
+            Field::getName,
+            field -> {
+              try {
+                Object result = null;
+                field.setAccessible(true);
+                result = field.get(instance);
+                return result != null ? result : "";
+              } catch (Exception e) {
+                return "";
+              }
+            }));
+  }
+
+  static Map<String, String> convertObjectToMapUsingObjectMapper(Employee employee) {
+
+    ObjectMapper objectMapper = new ObjectMapper();
+    objectMapper.registerModule(new JavaTimeModule());
+    objectMapper.setDateFormat(new SimpleDateFormat("yyyy-MM-dd"));
+
+    return objectMapper.convertValue(employee, Map.class);
+  }
+
+  static Properties convertObjectToMapUsingJavaPropsMapper(Employee employee)
+      throws IOException {
+
+    JavaPropsMapper mapper = new JavaPropsMapper();
+    mapper.registerModule(new JavaTimeModule());
+    mapper.setDateFormat(new SimpleDateFormat("yyyy-MM-dd"));
+
+    Properties properties = mapper.writeValueAsProperties(employee);
+    return properties;
+  }
+
+  static Map<String, String> convertObjectToMapUsingGson(Employee employee) {
+    Gson gson = new GsonBuilder()
+        .registerTypeAdapter(LocalDate.class, new LocalDateAdapter())
+        .create();
+
+    return gson.fromJson(gson.toJson(employee),
+        new TypeToken<HashMap<String, Object>>() {
+        }.getType()
+    );
+  }
+}
+
+class LocalDateAdapter implements JsonSerializer<LocalDate>, JsonDeserializer<LocalDate> {
+
+  @Override
+  public JsonElement serialize(LocalDate date, Type typeOfSrc, JsonSerializationContext context) {
+    return new JsonPrimitive(date.format(DateTimeFormatter.ISO_LOCAL_DATE)); // "yyyy-mm-dd"
+  }
+
+  @Override
+  public LocalDate deserialize(JsonElement jsonElement, Type type,
+      JsonDeserializationContext jsonDeserializationContext) throws JsonParseException {
+    String ldString = jsonElement.getAsString();
+    return LocalDate.parse(ldString, DateTimeFormatter.ISO_LOCAL_DATE);
+  }
+}

src/main/java/com/howtodoinjava/core/objectToMap/Employee.java

@@ -0,0 +1,28 @@
+package com.howtodoinjava.core.objectToMap;
+
+import java.time.LocalDate;
+import java.util.List;
+import lombok.AllArgsConstructor;
+import lombok.Data;
+import lombok.NoArgsConstructor;
+
+@Data
+@AllArgsConstructor
+@NoArgsConstructor
+public class Employee {
+  private Integer id;
+  private String name;
+  private LocalDate dateOfBirth;
+  private List<String> locations;
+  private List<Role> roles;
+}
+
+@Data
+@AllArgsConstructor
+@NoArgsConstructor
+class Role {
+  private Integer id;
+  private String name;
+}
+
+

src/main/java/com/howtodoinjava/core/objectToMap/README.md

@@ -0,0 +1,3 @@
+# Related Tutorials
+
+. [Convert an Object to Map](https://howtodoinjava.com/java/basics/convert-object-to-map/)