Bael 7805 how to fix json io exception failed making field property accessible in gson

json-modules/gson-4/gson-module-opens/pom.xml

@@ -0,0 +1,15 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<project xmlns="http://maven.apache.org/POM/4.0.0"
+    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">
+	<modelVersion>4.0.0</modelVersion>
+
+	<parent>
+		<groupId>com.baeldung</groupId>
+		<artifactId>gson-4</artifactId>
+		<version>1.0.0-SNAPSHOT</version>
+	</parent>
+
+	<artifactId>gson-module-opens</artifactId>
+	<packaging>jar</packaging>
+</project>
+

json-modules/gson-4/gson-module-opens/src/main/java/gson/exception/ConferencePojo.java

@@ -0,0 +1,23 @@
+package gson.exception;
+
+public class ConferencePojo {
+
+    private String name;
+    private int numberOfParticipants;
+
+    public String getName() {
+        return name;
+    }
+
+    public int getNumberOfParticipants() {
+        return numberOfParticipants;
+    }
+
+    public void setName(String name) {
+        this.name = name;
+    }
+
+    public void setNumberOfParticipants(int numberOfParticipants) {
+        this.numberOfParticipants = numberOfParticipants;
+    }
+}

json-modules/gson-4/gson-module-opens/src/main/java/gson/exception/ConferencePojoWithDate.java

@@ -0,0 +1,34 @@
+package gson.exception;
+
+import java.time.LocalDate;
+
+public class ConferencePojoWithDate {
+
+    private String name;
+    private int numberOfParticipants;
+    private LocalDate conferenceStart;
+
+    public String getName() {
+        return name;
+    }
+
+    public int getNumberOfParticipants() {
+        return numberOfParticipants;
+    }
+
+    public void setName(String name) {
+        this.name = name;
+    }
+
+    public void setNumberOfParticipants(int numberOfParticipants) {
+        this.numberOfParticipants = numberOfParticipants;
+    }
+
+    public LocalDate getConferenceStart() {
+        return conferenceStart;
+    }
+
+    public void setConferenceStart(LocalDate conferenceStart) {
+        this.conferenceStart = conferenceStart;
+    }
+}

json-modules/gson-4/gson-module-opens/src/main/java/gson/exception/GsonModuleMain.java

@@ -0,0 +1,36 @@
+package gson.exception;
+
+import java.time.LocalDate;
+
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+import com.google.gson.Gson;
+
+public class GsonModuleMain {
+
+    static Logger log = LoggerFactory.getLogger(GsonModuleMain.class);
+
+    public static void main(String[] args) {
+
+        String moduleName = GsonModuleMain.class.getModule()
+            .getName();
+
+        if (moduleName == null) {
+            log.info("Mode: [ Class Path ] (Class in the Unnamed Module)");
+        } else {
+            log.info("Mode: [ Module Path ] - Module name: " + moduleName);
+        }
+        LocalDate excpectedDate = LocalDate.of(2026, 8, 17);
+        Gson gson = new Gson();
+        String json = "{\"name\":\"Java Conference\"}";
+
+        try {
+            ConferencePojo pojo = gson.fromJson(json, ConferencePojo.class);
+            log.info("Deserialization successful! Object " + pojo);
+        } catch (Exception e) {
+            log.info("Expected exception caught!");
+            e.printStackTrace();
+        }
+    }
+}

json-modules/gson-4/gson-module-opens/src/main/java/module-info.java

@@ -0,0 +1,9 @@
+module gson.exception {
+
+    requires com.google.gson;
+    requires org.slf4j;
+
+    opens gson.exception to com.google.gson;
+
+    exports gson.exception;
+}

json-modules/gson-4/gson-module-opens/src/test/java/gson/exception/ModularOpensGsonUnitTest.java

@@ -0,0 +1,26 @@
+package gson.exception;
+
+import static org.junit.jupiter.api.Assertions.assertDoesNotThrow;
+import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertNotNull;
+
+import org.junit.jupiter.api.Test;
+
+import com.google.gson.Gson;
+
+class ModularOpensGsonUnitTest {
+
+    @Test
+    void givenModularAndOpens_whenDeserializingPojo_thenSuccess() {
+        String json = "{\"name\":\"Java Conference\",\"numberOfParticipants\":150}";
+        Gson gson = new Gson();
+
+        ConferencePojo result = assertDoesNotThrow(() -> {
+            return gson.fromJson(json, ConferencePojo.class);
+        });
+
+        assertNotNull(result);
+        assertEquals("Java Conference", result.getName());
+    }
+
+}

json-modules/gson-4/gson-module-opens/src/test/java/gson/exception/ModularStructureConfirmationUnitTest.java

@@ -0,0 +1,17 @@
+package gson.exception;
+
+import static org.junit.jupiter.api.Assertions.assertTrue;
+
+import org.junit.jupiter.api.Test;
+
+class ModularStructureConfirmationUnitTest {
+
+    @Test
+    void whenModular_thenModuleIsNamed() {
+        Module module = this.getClass()
+            .getModule();
+
+        assertTrue(module.isNamed(), "Test run on Classpath, JPMS strong encapsulation won't work!");
+    }
+
+}

json-modules/gson-4/gson-module-opens/src/test/java/gson/exception/PojoWithLocalDateUnitTest.java

@@ -0,0 +1,45 @@
+package gson.exception;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertThrows;
+
+import java.time.LocalDate;
+
+import org.junit.jupiter.api.Test;
+
+import com.google.gson.Gson;
+import com.google.gson.JsonSyntaxException;
+
+class PojoWithLocalDateUnitTest {
+
+    @Test
+    void whenObjectDateFormat_thenSuccessfulDeserialization() {
+        String correctJson = "{" 
+          + "\"name\":\"Java Conference\"," 
+          + "\"numberOfParticipants\":500," 
+          + "\"conferenceStart\":{\"year\":2026,\"month\":8,\"day\":17}"
+          + "}";
+
+        Gson gson = new Gson();
+        ConferencePojoWithDate result = gson.fromJson(correctJson, ConferencePojoWithDate.class);
+
+        LocalDate excpectedDate = LocalDate.of(2026, 8, 17);
+        assertEquals(excpectedDate, result.getConferenceStart(), "Date should be the same as in JSON");
+    }
+
+    @Test
+    void whenISOTextFormat_thenJsonSyntaxException() {
+
+        String wrongDateInJson = "{"
+          + "\"name\":\"Java Conference\"," 
+          + "\"numberOfParticipants\":500,"
+          + "\"conferenceStart\":\"2026-08-17\""
+          + "}";
+
+        Gson gson = new Gson();
+        assertThrows(JsonSyntaxException.class, () -> {
+            gson.fromJson(wrongDateInJson, ConferencePojoWithDate.class);
+        }, "JsonSyntaxException was expected due to an incompatible date format");
+
+    }
+}

json-modules/gson-4/gson-module/pom.xml

@@ -0,0 +1,14 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<project xmlns="http://maven.apache.org/POM/4.0.0"
+    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">
+	<modelVersion>4.0.0</modelVersion>
+
+	<parent>
+		<groupId>com.baeldung</groupId>
+		<artifactId>gson-4</artifactId>
+		<version>1.0.0-SNAPSHOT</version>
+	</parent>
+
+	<artifactId>gson-module</artifactId>
+	<packaging>jar</packaging>
+</project>

json-modules/gson-4/gson-module/src/main/java/gson/exception/ConferencePojo.java

@@ -0,0 +1,23 @@
+package gson.exception;
+
+public class ConferencePojo {
+
+    private String name;
+    private int numberOfParticipants;
+
+    public String getName() {
+        return name;
+    }
+
+    public int getNumberOfParticipants() {
+        return numberOfParticipants;
+    }
+
+    public void setName(String name) {
+        this.name = name;
+    }
+
+    public void setNumberOfParticipants(int numberOfParticipants) {
+        this.numberOfParticipants = numberOfParticipants;
+    }
+}

json-modules/gson-4/gson-module/src/main/java/gson/exception/ConferencePojoAdapter.java

@@ -0,0 +1,40 @@
+package gson.exception;
+
+import java.io.IOException;
+
+import com.google.gson.TypeAdapter;
+import com.google.gson.stream.JsonReader;
+import com.google.gson.stream.JsonWriter;
+
+public class ConferencePojoAdapter extends TypeAdapter<ConferencePojo> {
+
+    @Override
+    public void write(JsonWriter out, ConferencePojo value) throws IOException {
+        throw new UnsupportedOperationException("This adapter is for deserialization only!");
+    }
+
+    @Override
+    public ConferencePojo read(JsonReader in) throws IOException {
+        String name = null;
+        int numberOfParticipants = 0;
+
+        in.beginObject();
+        while (in.hasNext()) {
+            String key = in.nextName();
+            if ("name".equals(key)) {
+                name = in.nextString();
+            } else if ("numberOfParticipants".equals(key)) {
+                numberOfParticipants = in.nextInt();
+            } else {
+                in.skipValue();
+            }
+        }
+        in.endObject();
+
+        ConferencePojo result = new ConferencePojo();
+        result.setName(name);
+        result.setNumberOfParticipants(numberOfParticipants);
+
+        return result;
+    }
+}

json-modules/gson-4/gson-module/src/main/java/gson/exception/ConferencePojoPublic.java

@@ -0,0 +1,7 @@
+package gson.exception;
+
+public class ConferencePojoPublic {
+
+    public String name;
+    public int numberOfParticipants;
+}

json-modules/gson-4/gson-module/src/main/java/gson/exception/ConferenceRecord.java

@@ -0,0 +1,5 @@
+package gson.exception;
+
+public record ConferenceRecord(String name, int numberOfParticipants) {
+
+}

json-modules/gson-4/gson-module/src/main/java/gson/exception/GsonModuleMain.java

@@ -0,0 +1,34 @@
+package gson.exception;
+
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+import com.google.gson.Gson;
+
+public class GsonModuleMain {
+
+    static Logger log = LoggerFactory.getLogger(GsonModuleMain.class);
+
+    public static void main(String[] args) {
+
+        String moduleName = GsonModuleMain.class.getModule()
+            .getName();
+
+        if (moduleName == null) {
+            log.info("Mode: [ Class Path ] (Class in the Unnamed Module)");
+        } else {
+            log.info("Mode: [ Module Path ] - Module name: " + moduleName);
+        }
+
+        Gson gson = new Gson();
+        String json = "{\"name\":\"Java Conference\"}";
+
+        try {
+            ConferencePojo pojo = gson.fromJson(json, ConferencePojo.class);
+            log.info("Deserialization successful! Object " + pojo);
+        } catch (Exception e) {
+            log.info("Expected exception caught!");
+            e.printStackTrace();
+        }
+    }
+}

json-modules/gson-4/gson-module/src/main/java/module-info.java

@@ -0,0 +1,7 @@
+module gson.exception {
+
+    requires com.google.gson;
+    requires org.slf4j;
+
+    exports gson.exception;
+}