Using with Java

This article describes how to use Apollo Kotlin in Java projects.

Use the Java codegen

Apollo Kotlin generates Kotlin code by default, but you can configure it to use the Java codegen instead:

build.gradle[.kts]

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apollo {
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  service("service") {
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    generateKotlinModels.set(false)
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  }
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}

The default runtime for Apollo Kotlin, apollo-runtime, exposes a coroutines / Flow-based API that isn't well suited to be consumed from Java. That is why a specific runtime, apollo-runtime-java is available to use Apollo Kotlin from Java. To use it, add a dependency on this runtime instead of the default one:

build.gradle[.kts]

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dependencies {
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  // ...
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  // Use apollo-runtime-java instead of apollo-runtime
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  implementation("com.apollographql.apollo3:apollo-runtime-java:4.0.0-beta.2")
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}

The Java runtime has a callbacks based API. This snippet demonstrates initializing and using an ApolloClient in Java:

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import com.apollographql.apollo3.runtime.java.ApolloClient;
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// (...)
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ApolloClient client = ApolloClient.Builder builder = new ApolloClient.Builder()
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  .serverUrl("http://localhost:4000/graphql")
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  .build();
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// Use enqueue to execute a query asynchronously
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apolloClient.query(new GetRandomQuery()).enqueue(response -> {
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  if (response.data != null) {
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    // No errors
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    System.out.println(response.data);
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  } else {
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    // Errors
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    if (response.exception instanceof ApolloGraphQLException) {
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      // GraphQL errors
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      System.out.println(((ApolloGraphQLException) response.exception).getErrors().get(0));
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    } else {
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      // Network error
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      response.exception.printStackTrace();
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    }
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  }
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});

Note that as of now, the Java runtime doesn't support the Http or Normalized caches.

Cancelling requests

euqueue returns an ApolloDisposable that can be used to cancel the request:

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ApolloDisposable disposable = apolloClient.subscription(new MyQuery()).enqueue(response -> ...)
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// ...
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disposable.dispose();

RxJava extensions

If your project uses RxJava, you can use Apollo's RxJava extensions with the Java runtime.

Using aliases

Kotlin native