<!--
name: 'Data: Claude API reference — Java'
description: Java SDK reference including installation, client initialization, basic requests, streaming, and beta tool use
ccVersion: 2.1.47
-->
# Claude API — Java

> **Note:** The Java SDK supports the Claude API and beta tool use with annotated classes. Agent SDK is not yet available for Java.

## Installation

Maven:

\`\`\`xml
<dependency>
    <groupId>com.anthropic</groupId>
    <artifactId>anthropic-java</artifactId>
    <version>2.11.1</version>
</dependency>
\`\`\`

Gradle:

\`\`\`groovy
implementation("com.anthropic:anthropic-java:2.11.1")
\`\`\`

## Client Initialization

\`\`\`java
import com.anthropic.client.AnthropicClient;
import com.anthropic.client.okhttp.AnthropicOkHttpClient;

// Default (reads ANTHROPIC_API_KEY from environment)
AnthropicClient client = AnthropicOkHttpClient.fromEnv();

// Explicit API key
AnthropicClient client = AnthropicOkHttpClient.builder()
    .apiKey("your-api-key")
    .build();
\`\`\`

---

## Basic Message Request

\`\`\`java
import com.anthropic.models.messages.MessageCreateParams;
import com.anthropic.models.messages.Message;
import com.anthropic.models.messages.Model;

MessageCreateParams params = MessageCreateParams.builder()
    .model(Model.CLAUDE_OPUS_4_6)
    .maxTokens(1024L)
    .addUserMessage("What is the capital of France?")
    .build();

Message response = client.messages().create(params);
response.content().stream()
    .flatMap(block -> block.text().stream())
    .forEach(textBlock -> System.out.println(textBlock.text()));
\`\`\`

---

## Streaming

\`\`\`java
MessageCreateParams params = MessageCreateParams.builder()
    .model(Model.CLAUDE_OPUS_4_6)
    .maxTokens(1024L)
    .addUserMessage("Write a haiku")
    .build();

try (var streamResponse = client.messages().createStreaming(params)) {
    streamResponse.stream().forEach(event -> {
        event.contentBlockDelta().ifPresent(deltaEvent ->
            deltaEvent.delta().text().ifPresent(td ->
                System.out.print(td.text())
            )
        );
    });
}
\`\`\`

---

## Tool Use (Beta)

The Java SDK supports beta tool use with annotated classes. Tool classes implement \`Supplier<String>\` for automatic execution via \`BetaToolRunner\`.

### Tool Runner (automatic loop)

\`\`\`java
import com.anthropic.models.beta.messages.MessageCreateParams;
import com.anthropic.models.beta.messages.BetaMessage;
import com.anthropic.helpers.BetaToolRunner;
import com.fasterxml.jackson.annotation.JsonClassDescription;
import com.fasterxml.jackson.annotation.JsonPropertyDescription;
import java.util.function.Supplier;

@JsonClassDescription("Get the weather in a given location")
static class GetWeather implements Supplier<String> {
    @JsonPropertyDescription("The city and state, e.g. San Francisco, CA")
    public String location;

    @Override
    public String get() {
        return "The weather in " + location + " is sunny and 72°F";
    }
}

BetaToolRunner toolRunner = client.beta().messages().toolRunner(
    MessageCreateParams.builder()
        .model("claude-opus-4-6")
        .maxTokens(1024L)
        .addTool(GetWeather.class)
        .addUserMessage("What's the weather in San Francisco?")
        .build());

for (BetaMessage message : toolRunner) {
    System.out.println(message);
}
\`\`\`

### Manual Loop

For manual tool loops, define tools as JSON schema in the request, handle \`tool_use\` blocks in the response, send \`tool_result\` back, and loop until \`stop_reason\` is \`"end_turn"\`. See the [shared tool use concepts](../shared/tool-use-concepts.md) for the agentic loop pattern.