JIRA BAEL-6693, difference between Gson @Expose and @SerializedName (#14370)

Co-authored-by: parthiv39731 <parthiv39731@gmail.com>

json-modules/gson-2/src/main/java/com/baeldung/gson/entities/BankAccount.java

@@ -0,0 +1,31 @@
+package com.baeldung.gson.entities;
+
+import com.google.gson.annotations.Expose;
+
+public class BankAccount {
+    @Expose(serialize = false, deserialize = false)
+    private String accountNumber;
+    @Expose(serialize = true, deserialize = true)
+    private String bankName;
+
+    public BankAccount(String accountNumber, String bankName) {
+        this.accountNumber = accountNumber;
+        this.bankName = bankName;
+    }
+
+    public String getAccountNumber() {
+        return accountNumber;
+    }
+
+    public void setAccountNumber(String accountNumber) {
+        this.accountNumber = accountNumber;
+    }
+
+    public String getBankName() {
+        return bankName;
+    }
+
+    public void setBankName(String bankName) {
+        this.bankName = bankName;
+    }
+}

json-modules/gson-2/src/main/java/com/baeldung/gson/entities/Country.java

@@ -0,0 +1,50 @@
+package com.baeldung.gson.entities;
+
+import com.google.gson.annotations.SerializedName;
+
+public class Country {
+    @SerializedName(value = "name")
+    private String countryName;
+    @SerializedName(value = "capital")
+    private String countryCapital;
+    @SerializedName(value = "continent")
+    private String continentName;
+
+    public Country(String countryName, String countryCapital, String continentName) {
+        this.countryName = countryName;
+        this.countryCapital = countryCapital;
+        this.continentName = continentName;
+    }
+    @Override
+    public String toString() {
+        return "Country{" +
+                "countryName='" + countryName + '\'' +
+                ", countryCapital='" + countryCapital + '\'' +
+                ", continentName='" + continentName + '\'' +
+                '}';
+    }
+
+    public String getCountryName() {
+        return countryName;
+    }
+
+    public void setCountryName(String countryName) {
+        this.countryName = countryName;
+    }
+
+    public String getCountryCapital() {
+        return countryCapital;
+    }
+
+    public void setCountryCapital(String countryCapital) {
+        this.countryCapital = countryCapital;
+    }
+
+    public String getContinentName() {
+        return continentName;
+    }
+
+    public void setContinentName(String continentName) {
+        this.continentName = continentName;
+    }
+}

json-modules/gson-2/src/main/java/com/baeldung/gson/entities/Person.java

@@ -0,0 +1,69 @@
+package com.baeldung.gson.entities;
+
+import com.google.gson.annotations.Expose;
+
+
+import java.util.List;
+
+public class Person {
+
+    public Person(String firstName, String lastName, String emailAddress, String password, List<BankAccount> bankAccounts) {
+        this.firstName = firstName;
+        this.lastName = lastName;
+        this.emailAddress = emailAddress;
+        this.password = password;
+        this.bankAccounts = bankAccounts;
+    }
+
+    @Expose(serialize = true)
+    private String firstName;
+    @Expose(serialize = true)
+    private String lastName;
+    @Expose()
+    private String emailAddress;
+    @Expose(serialize = false)
+    private String password;
+
+    @Expose(serialize = true)
+    private List<BankAccount> bankAccounts;
+
+    public List<BankAccount> getBankAccounts() {
+        return bankAccounts;
+    }
+
+    public void setBankAccounts(List<BankAccount> bankAccounts) {
+        this.bankAccounts = bankAccounts;
+    }
+
+    public String getLastName() {
+        return lastName;
+    }
+
+    public void setLastName(String lastName) {
+        this.lastName = lastName;
+    }
+
+    public String getEmailAddress() {
+        return emailAddress;
+    }
+
+    public void setEmailAddress(String emailAddress) {
+        this.emailAddress = emailAddress;
+    }
+
+    public String getPassword() {
+        return password;
+    }
+
+    public void setPassword(String password) {
+        this.password = password;
+    }
+
+    public String getFirstName() {
+        return firstName;
+    }
+
+    public void setFirstName(String firstName) {
+        this.firstName = firstName;
+    }
+}

json-modules/gson-2/src/main/java/com/baeldung/gson/exposevsserializedname/PersonSerializer.java

@@ -0,0 +1,27 @@
+package com.baeldung.gson.exposevsserializedname;
+
+import com.baeldung.gson.entities.Country;
+import com.baeldung.gson.entities.Person;
+import com.google.gson.Gson;
+import com.google.gson.GsonBuilder;
+
+public class PersonSerializer {
+    private static final Gson configuredGson = new GsonBuilder().excludeFieldsWithoutExposeAnnotation().create();
+    private static final Gson defaultGson = new Gson();
+
+    public static String serializeWithConfiguredGson(Person person) {
+        return configuredGson.toJson(person);
+    }
+
+    public static String serializeWithDefaultGson(Person person) {
+        return defaultGson.toJson(person);
+    }
+
+    public static String toJsonString(Object obj) {
+        return defaultGson.toJson(obj);
+    }
+
+    public static Country fromJsonString(String json) {
+        return defaultGson.fromJson(json, Country.class);
+    }
+}

json-modules/gson-2/src/test/java/com/baeldung/gson/exposevsserializedname/PersonSerializerUnitTest.java

@@ -0,0 +1,75 @@
+package com.baeldung.gson.exposevsserializedname;
+
+import com.baeldung.gson.entities.BankAccount;
+import com.baeldung.gson.entities.Country;
+import com.baeldung.gson.entities.Person;
+
+import org.junit.Before;
+import org.junit.Test;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+import java.util.ArrayList;
+import java.util.List;
+
+import static org.junit.Assert.*;
+
+public class PersonSerializerUnitTest {
+    private static final Logger logger = LoggerFactory.getLogger(PersonSerializerUnitTest.class);
+    private Person person = null;
+    private Country country = null;
+    @Before
+    public void preparePersonObj() {
+        List<BankAccount> accounts = new ArrayList<>();
+        BankAccount acc1 = new BankAccount("4565432312", "Bank of America");
+        BankAccount acc2 = new BankAccount("4565432616", "Bank of America");
+        accounts.add(acc1);
+        accounts.add(acc2);
+        person = new Person(
+                "James", "Cameron", "james.cameron@gmail.com",
+                "secret", accounts);
+
+        country = new Country("India", "New Delhi", "Asia");
+    }
+
+    @Test
+    public void WhenUseCustomGson_ThenDonotSerializeAccountNumAndPassword () {
+
+        String personJson = PersonSerializer.serializeWithConfiguredGson(person);
+        logger.info(personJson);
+        assertFalse("Test failed: password found", personJson.contains("password"));
+        assertFalse("Test failed: account number found", personJson.contains("accountNumber:"));
+    }
+
+    @Test
+    public void WhenUseDefaultGson_ThenSerializeAccountNumAndPassword () {
+
+        String personJson = PersonSerializer.serializeWithDefaultGson(person);
+        logger.info(personJson);
+        assertTrue("Test failed: password not found", personJson.contains("password"));
+        assertTrue("Test failed: account number not found", personJson.contains("accountNumber"));
+    }
+
+    @Test
+    public void whenUseSerializedAnnotation_ThenUseSerializedNameinJsonString() {
+        String countryJson = PersonSerializer.toJsonString(country);
+        logger.info(countryJson);
+        assertFalse("Test failed: No change in the keys", countryJson.contains("countryName"));
+        assertFalse("Test failed: No change in the keys", countryJson.contains("contentName"));
+        assertFalse("Test failed: No change in the keys", countryJson.contains("countryCapital"));
+
+        assertTrue("Test failed: No change in the keys", countryJson.contains("name"));
+        assertTrue("Test failed: No change in the keys", countryJson.contains("continent"));
+        assertTrue("Test failed: No change in the keys", countryJson.contains("capital"));
+    }
+
+    @Test
+    public void whenJsonStrCreatedWithCustomKeys_ThenCreateObjUsingGson() {
+        String countryJson = PersonSerializer.toJsonString(country);
+        Country country = PersonSerializer.fromJsonString(countryJson);
+        logger.info(country.toString());
+        assertEquals("Fail: Object creation failed", country.getCountryName(), "India");
+        assertEquals("Fail: Object creation failed", country.getCountryCapital(), "New Delhi");
+        assertEquals("Fail: Object creation failed", country.getContinentName(), "Asia");
+    }
+}