diff --git a/.idea/compiler.xml b/.idea/compiler.xml
index 61a9130..b86273d 100644
--- a/.idea/compiler.xml
+++ b/.idea/compiler.xml
@@ -1,6 +1,6 @@
 <?xml version="1.0" encoding="UTF-8"?>
 <project version="4">
   <component name="CompilerConfiguration">
-    <bytecodeTargetLevel target="1.8" />
+    <bytecodeTargetLevel target="21" />
   </component>
 </project>
\ No newline at end of file
diff --git a/.idea/gradle.xml b/.idea/gradle.xml
index efacb99..7b3006b 100644
--- a/.idea/gradle.xml
+++ b/.idea/gradle.xml
@@ -6,7 +6,7 @@
       <GradleProjectSettings>
         <option name="testRunner" value="CHOOSE_PER_TEST" />
         <option name="externalProjectPath" value="$PROJECT_DIR$" />
-        <option name="gradleJvm" value="jbr-21" />
+        <option name="gradleJvm" value="#GRADLE_LOCAL_JAVA_HOME" />
         <option name="modules">
           <set>
             <option value="$PROJECT_DIR$" />
diff --git a/.idea/misc.xml b/.idea/misc.xml
index 098b443..a60d85d 100644
--- a/.idea/misc.xml
+++ b/.idea/misc.xml
@@ -1,3 +1,4 @@
+<?xml version="1.0" encoding="UTF-8"?>
 <project version="4">
   <component name="AndroidDexCompilerConfiguration">
     <option name="FORCE_JUMBO" value="true" />
@@ -11,7 +12,7 @@
   <component name="Kotlin2JsCompilerArguments">
     <option name="sourceMapEmbedSources" />
   </component>
-  <component name="ProjectRootManager" version="2" languageLevel="JDK_1_8" default="true" project-jdk-name="1.8" project-jdk-type="JavaSDK">
+  <component name="ProjectRootManager" version="2" languageLevel="JDK_21" default="true" project-jdk-name="jbr-21" project-jdk-type="JavaSDK">
     <output url="file://$PROJECT_DIR$/build/classes" />
   </component>
   <component name="ProjectType">
diff --git a/app/build.gradle b/app/build.gradle
index 8a53ccc..371aff6 100644
--- a/app/build.gradle
+++ b/app/build.gradle
@@ -44,6 +44,32 @@ android {
         sourceCompatibility JavaVersion.VERSION_17
         targetCompatibility JavaVersion.VERSION_17
     }
+    
+    // Enable JUnit 5 (Jupiter) support
+    testOptions {
+        unitTests.all {
+            useJUnitPlatform()
+        }
+    }
+}
+
+apollo {
+    service("contentstack") {
+        packageName.set("com.contentstack.graphql")
+        
+        // Generate Java models instead of Kotlin
+        generateKotlinModels.set(false)
+        
+        // Apollo v4 configuration
+        // Generates operation output classes
+        generateOperationOutput.set(true)
+        
+        // Use semantic nullability for better null handling
+        generateOptionalOperationVariables.set(true)
+        
+        // Schema location
+        schemaFile.set(file("src/main/graphql/com/contentstack/graphql/schema.json"))
+    }
 }
 
 configurations.all {
@@ -57,18 +83,36 @@ configurations.all {
 
 dependencies {
     implementation fileTree(dir: 'libs', include: ['*.jar'])
-    implementation 'androidx.appcompat:appcompat:1.3.0-alpha01'
-    implementation 'androidx.constraintlayout:constraintlayout:1.1.3'
-    implementation 'androidx.swiperefreshlayout:swiperefreshlayout:1.0.0'
-    testImplementation 'junit:junit:4.13.2'
+    
+    // AndroidX Libraries
+    implementation 'androidx.appcompat:appcompat:1.6.1'
+    implementation 'androidx.constraintlayout:constraintlayout:2.1.4'
+    implementation 'androidx.swiperefreshlayout:swiperefreshlayout:1.1.0'
+    implementation 'androidx.recyclerview:recyclerview:1.3.2'
+    implementation 'androidx.cardview:cardview:1.0.0'
+    implementation 'com.google.android.material:material:1.11.0'
+    
+    // Testing - JUnit 5 (Jupiter) uses Apache 2.0 license
+    testImplementation 'org.junit.jupiter:junit-jupiter-api:5.10.1'
+    testRuntimeOnly 'org.junit.jupiter:junit-jupiter-engine:5.10.1'
+    testImplementation 'org.junit.vintage:junit-vintage-engine:5.10.1' // For JUnit 4 compatibility
     androidTestImplementation 'androidx.test:runner:1.5.2'
     androidTestImplementation 'androidx.test.espresso:espresso-core:3.5.1'
-    implementation 'androidx.recyclerview:recyclerview:1.1.0'
-    implementation 'com.github.bumptech.glide:glide:4.11.0'
-    annotationProcessor 'com.github.bumptech.glide:compiler:4.7.1'
-    implementation 'androidx.recyclerview:recyclerview:1.1.0'
-    implementation 'androidx.cardview:cardview:1.0.0'
-    implementation 'com.google.android.material:material:1.1.0'
-    implementation 'org.jetbrains:annotations:16.0.1'
-    implementation 'com.apollographql.apollo:apollo-runtime:2.5.14'
+    
+    // Image Loading
+    implementation 'com.github.bumptech.glide:glide:4.16.0'
+    annotationProcessor 'com.github.bumptech.glide:compiler:4.16.0'
+    
+    // Apollo GraphQL v4
+    implementation 'com.apollographql.apollo:apollo-runtime:4.0.0'
+    
+    // Apollo adapters for Java/blocking calls
+    implementation 'com.apollographql.apollo:apollo-adapters:4.0.0'
+    
+    // Kotlin coroutines (required for Apollo v4)
+    implementation 'org.jetbrains.kotlinx:kotlinx-coroutines-core:1.7.3'
+    implementation 'org.jetbrains.kotlinx:kotlinx-coroutines-android:1.7.3'
+    
+    // Annotations
+    implementation 'org.jetbrains:annotations:24.1.0'
 }
diff --git a/app/proguard-rules.pro b/app/proguard-rules.pro
index f1b4245..d61ef7a 100644
--- a/app/proguard-rules.pro
+++ b/app/proguard-rules.pro
@@ -19,3 +19,30 @@
 # If you keep the line number information, uncomment this to
 # hide the original source file name.
 #-renamesourcefileattribute SourceFile
+
+# Apollo GraphQL v4 ProGuard Rules
+-keep class com.apollographql.apollo.** { *; }
+-keep class * extends com.apollographql.apollo.api.Query { *; }
+-keep class * extends com.apollographql.apollo.api.Mutation { *; }
+-keep class * extends com.apollographql.apollo.api.Subscription { *; }
+-keep class * extends com.apollographql.apollo.api.Fragment { *; }
+-keepclassmembers class * { @com.apollographql.apollo.api.* <fields>; }
+
+# Keep generated GraphQL models
+-keep class com.contentstack.graphql.** { *; }
+
+# OkHttp
+-dontwarn okhttp3.**
+-dontwarn okio.**
+-keepnames class okhttp3.internal.publicsuffix.PublicSuffixDatabase
+
+# Kotlin
+-keep class kotlin.** { *; }
+-keep class kotlin.Metadata { *; }
+-dontwarn kotlin.**
+-keepclassmembers class **$WhenMappings {
+    <fields>;
+}
+-keepclassmembers class kotlin.Metadata {
+    public <methods>;
+}
diff --git a/app/src/main/java/com/contentstack/graphql/product/holder/ViewHolder.java b/app/src/main/java/com/contentstack/graphql/product/holder/ViewHolder.java
index 83614b3..fe77db0 100644
--- a/app/src/main/java/com/contentstack/graphql/product/holder/ViewHolder.java
+++ b/app/src/main/java/com/contentstack/graphql/product/holder/ViewHolder.java
@@ -30,14 +30,14 @@ private void findViews(View itemView) {
     @SuppressLint("SetTextI18n")
     public void setData(ALLProductsQuery.Item data) {
 
-        txtTitle.setText(data.title());
-        txtPrice.setText("$"+data.price());
+        txtTitle.setText(data.title);
+        txtPrice.setText("$"+data.price);
 
         // Case: BASE_URL
-        //Glide.with(iconThumbnail.getContext()).load(data.featured_image().get(0).url()).thumbnail(0.1f).into(iconThumbnail);
+        //Glide.with(iconThumbnail.getContext()).load(data.featured_image.get(0).url).thumbnail(0.1f).into(iconThumbnail);
 
         // CASE: DEV8_URL
-        Glide.with(iconThumbnail.getContext()).load(data.featured_imageConnection().edges().get(0).node().url()).thumbnail(0.1f).into(iconThumbnail);
+        Glide.with(iconThumbnail.getContext()).load(data.featured_imageConnection.edges.get(0).node.url).thumbnail(0.1f).into(iconThumbnail);
     }
 
 }
diff --git a/app/src/main/java/com/contentstack/graphql/product/view/ProductActivity.java b/app/src/main/java/com/contentstack/graphql/product/view/ProductActivity.java
index 8ee2bc6..6f2c87d 100644
--- a/app/src/main/java/com/contentstack/graphql/product/view/ProductActivity.java
+++ b/app/src/main/java/com/contentstack/graphql/product/view/ProductActivity.java
@@ -1,22 +1,25 @@
 package com.contentstack.graphql.product.view;
 
-import androidx.annotation.RequiresApi;
 import androidx.appcompat.app.AppCompatActivity;
 import androidx.databinding.DataBindingUtil;
 import androidx.recyclerview.widget.GridLayoutManager;
 import androidx.recyclerview.widget.RecyclerView;
 
-import okhttp3.OkHttpClient;
-
-import android.os.Build;
 import android.os.Bundle;
 import android.util.Log;
 import android.view.View;
 
-import com.apollographql.apollo.ApolloCall;
 import com.apollographql.apollo.ApolloClient;
-import com.apollographql.apollo.api.Response;
+import com.apollographql.apollo.api.ApolloResponse;
 import com.apollographql.apollo.exception.ApolloException;
+
+import java.util.concurrent.ExecutorService;
+import java.util.concurrent.Executors;
+
+import kotlin.coroutines.Continuation;
+import kotlin.coroutines.CoroutineContext;
+import kotlin.coroutines.EmptyCoroutineContext;
+import kotlinx.coroutines.BuildersKt;
 import com.contentstack.graphql.ALLProductsQuery;
 import com.contentstack.graphql.BuildConfig;
 import com.contentstack.graphql.databinding.ProductsLayoutBinding;
@@ -37,6 +40,7 @@ public class ProductActivity extends AppCompatActivity {
     private ProductsLayoutBinding binding;
     private ProductAdapter adapter;
     private GridLayoutManager gridLayoutManager;
+    private ExecutorService executorService;
 
     private int mTotalItemCount = 0;
     private int mLastVisibleItemPosition;
@@ -48,15 +52,26 @@ protected void onCreate(Bundle savedInstanceState) {
         super.onCreate(savedInstanceState);
         binding = DataBindingUtil.setContentView(this, R.layout.products_layout);
 
+        executorService = Executors.newSingleThreadExecutor();
         getApolloClient();
         setToolbar();
     }
 
+    @Override
+    protected void onDestroy() {
+        super.onDestroy();
+        if (executorService != null && !executorService.isShutdown()) {
+            executorService.shutdown();
+        }
+    }
+
 
     private ApolloClient getApolloClient() {
-        OkHttpClient okHttpClient = new OkHttpClient.Builder().build();
         Log.e("Graphql URL:", BASE_URL);
-        return ApolloClient.builder().serverUrl(BASE_URL).okHttpClient(okHttpClient).build();
+        // Apollo v4 - serverUrl is sufficient, it uses OkHttp by default
+        return new ApolloClient.Builder()
+                .serverUrl(BASE_URL)
+                .build();
     }
 
 
@@ -97,42 +112,71 @@ public void onScrolled(@NotNull RecyclerView recyclerView, int dx, int dy) {
     private void getProducts(int skipCount, int limit) {
 
         binding.refreshContainer.setRefreshing(true);
-        getApolloClient().query(ALLProductsQuery.builder()
-                .skip(skipCount)
-                .limit(limit)
-                .build()).enqueue(new ApolloCall.Callback<ALLProductsQuery.Data>() {
-            @RequiresApi(api = Build.VERSION_CODES.N)
-            @Override
-            public void onResponse(@NotNull Response<ALLProductsQuery.Data> response) {
-                if (response.data() != null) {
-                    response.data().all_product().items().forEach(item -> {
-                        Log.i("Title", item.title());
-                        Log.i("Price", item.price().toString());
-                        Log.i("description", item.description());
-                        Log.e("image", item.featured_imageConnection().edges().get(0).node().url());
+        
+        // Apollo v4 requires coroutines - use runBlocking from Java
+        // Execute in background thread
+        executorService.execute(() -> {
+            try {
+                // Use Kotlin's runBlocking to call the suspend function from Java
+                ApolloResponse<ALLProductsQuery.Data> response = BuildersKt.runBlocking(
+                        EmptyCoroutineContext.INSTANCE,
+                        (scope, continuation) -> getApolloClient().query(
+                                new ALLProductsQuery(
+                                        com.apollographql.apollo.api.Optional.present(skipCount),
+                                        com.apollographql.apollo.api.Optional.present(limit)
+                                )
+                        ).execute(continuation)
+                );
+
+                // Check for errors in response
+                if (response.hasErrors()) {
+                    String errorMessage = response.errors != null && !response.errors.isEmpty() 
+                            ? response.errors.get(0).getMessage() 
+                            : "Unknown error occurred";
+                    Log.e("GraphQL Error", errorMessage);
+                    
+                    ProductActivity.this.runOnUiThread(() -> {
+                        binding.refreshContainer.setRefreshing(false);
+                        binding.tvError.setVisibility(View.VISIBLE);
+                        binding.tvError.setText(String.format("Error Occurred: %s", errorMessage));
                     });
+                    return;
+                }
+
+                // Process successful response
+                if (response.data != null) {
+                    ALLProductsQuery.Data data = response.data;
+                    
+                    // Log data (Java 7 compatible loop)
+                    for (ALLProductsQuery.Item item : data.all_product.items) {
+                        Log.i("Title", item.title);
+                        Log.i("Price", item.price.toString());
+                        Log.i("description", item.description);
+                        if (!item.featured_imageConnection.edges.isEmpty()) {
+                            Log.e("image", item.featured_imageConnection.edges.get(0).node.url);
+                        }
+                    }
+                    
                     ProductActivity.this.runOnUiThread(() -> {
                         binding.tvError.setVisibility(View.GONE);
                         binding.refreshContainer.setRefreshing(false);
 
-                        if (response.data().all_product().items().size() > 0) {
-                            Log.i(TAG, response.data().all_product().items().toString());
-                            adapter.addAll(response.data().all_product().items());
+                        if (data.all_product.items.size() > 0) {
+                            Log.i(TAG, data.all_product.items.toString());
+                            adapter.addAll(data.all_product.items);
                             binding.recyclerView.setAdapter(adapter);
                             adapter.notifyDataSetChanged();
                         }
                     });
                 }
-            }
-
-            @Override
-            public void onFailure(@NotNull ApolloException e) {
-                Log.e("onFailure", e.getMessage());
+                
+            } catch (Exception e) {
+                Log.e("onFailure", e.getMessage() != null ? e.getMessage() : "Unknown error");
                 ProductActivity.this.runOnUiThread(() -> {
                     binding.refreshContainer.setRefreshing(false);
                     binding.tvError.setVisibility(View.VISIBLE);
-                    binding.tvError.setText(String.format("Error Occurred %s",
-                            e.getLocalizedMessage()));
+                    binding.tvError.setText(String.format("Error Occurred: %s",
+                            e.getLocalizedMessage() != null ? e.getLocalizedMessage() : "Network error"));
                 });
             }
         });
diff --git a/build.gradle b/build.gradle
index b0a6c7b..e167306 100644
--- a/build.gradle
+++ b/build.gradle
@@ -7,7 +7,7 @@ buildscript {
     }
     dependencies {
         classpath 'com.android.tools.build:gradle:8.2.2'
-        classpath 'com.apollographql.apollo:apollo-gradle-plugin:2.5.14'
+        classpath 'com.apollographql.apollo:apollo-gradle-plugin:4.0.0'
     }
 }