claude-code-system-prompts/system-prompts/data-claude-api-reference-java.md
2026-06-18 17:15:00 -06:00

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<!--
name: 'Data: Claude API reference — Java'
description: Java SDK reference including installation, client initialization, basic requests, streaming, and beta tool use
ccVersion: 2.1.182
-->
# 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.
## Package Reference
Types are organized by package. If a class you need isn't shown in an example below, locate it via this table first — don't block on fetching SDK source over the network.
| `import` prefix | Contains |
|---|---|
| `com.anthropic.client` / `com.anthropic.client.okhttp` | `AnthropicClient`, `AnthropicOkHttpClient` |
| `com.anthropic.models.messages` | non-beta request/response types — `MessageCreateParams`, `Model`, `Message`, `TextBlockParam`, `ContentBlockParam`, `ToolUseBlockParam`, `ToolResultBlockParam`, `CacheControlEphemeral`, `Tool*` (e.g. `ToolBash20250124`, `ToolTextEditor20250728`), `StopReason`, `StructuredMessage*` |
| `com.anthropic.models.messages.batches` | Batch API — `BatchResultsParams`, `MessageBatchIndividualResponse` |
| `com.anthropic.models.beta` | `AnthropicBeta` (beta-flag constants) |
| `com.anthropic.models.beta.messages` | beta-endpoint types — `MessageCreateParams`, `BetaMessage`, `BetaStopReason`, `BetaContextManagementConfig`, `BetaMcpToolset`, `BetaRequestMcpServerUrlDefinition`, `BetaTool*` |
| `com.anthropic.core` | `JsonValue`, `JsonField`, `JsonSchemaLocalValidation`, `com.anthropic.core.http.StreamResponse` |
| `com.anthropic.errors` | typed exceptions — `AnthropicServiceException`, `RateLimitException`, `NotFoundException`, etc. (see `shared/error-codes.md`) |
`client.messages()` uses `com.anthropic.models.messages.*`; `client.beta().messages()` uses `com.anthropic.models.beta.messages.*`. Both packages define a `MessageCreateParams` — import the one matching the client path you call.
### Key types per feature
Write from this table instead of `javap`/jar inspection. Endpoint column tells you whether to use `client.messages()` or `client.beta().messages()`.
| Feature | Endpoint | Key Java types / builder calls |
|---|---|---|
| User profiles | beta | `client.beta().userProfiles().create(...)` / `.retrieve(id)` / `.list()`. Pass the returned profile id on the beta `MessageCreateParams`. Requires a beta header — check the SDK's beta-headers reference for the current flag. |
| Agent Skills | beta | `BetaContainerParams`, `BetaSkillParams`, `BetaCodeExecutionTool20250825`. `.addBeta("code-execution-2025-08-25").addBeta("skills-2025-10-02")`. Download the output via `client.beta().files().download(fileId)`. |
| Cache diagnostics | beta | `BetaDiagnosticsParam`, `BetaCacheControlEphemeral` |
| Context editing | beta | `.contextManagement(BetaContextManagementConfig.builder()…)`. The edit strategy is a `BetaClearToolUses20250919Edit` (or `BetaClearThinking20251015Edit`); its trigger is a `BetaInputTokensTrigger` built separately and passed to the edit's builder — there is no direct `.inputTokensTrigger(N)` shortcut on the edit builder. `javap` the edit and trigger classes for the exact setter names. |
| Memory tool | non-beta | `.addTool(MemoryTool20250818.builder().build())` from `com.anthropic.models.messages` |
| Programmatic tool calling | non-beta | `CodeExecutionTool20260120`, `Tool`, `ContentBlockParam` |
| Strict tool use | non-beta | `Tool`, `Tool.InputSchema` |
| Task budgets | beta | `.outputConfig(BetaOutputConfig.builder().taskBudget(BetaTokenTaskBudget.builder()...))` |
| Tool search | non-beta | `.addTool(ToolSearchToolRegex20251119.builder()...)` from `com.anthropic.models.messages` |
| Web search | non-beta | `WebSearchTool20260209` from `com.anthropic.models.messages` — the latest variant with dynamic filtering (Opus 4.8/4.7/4.6 + Sonnet 4.6). For older models or Vertex, use `WebSearchTool20250305` |
### Discovering type and member names
If a class or builder method you need isn't in the tables above, `jar tf <anthropic-java-core jar> | grep -i <term>` or `javap -classpath <jar> com.anthropic.models.…` is fast enough to locate names. **Do not compile and run a separate reflection program** to enumerate members — the first build is slow enough to be backgrounded in many environments, trapping you in a polling loop. Write the script with the names you found and let the compiler error (`cannot find symbol`) point at any wrong member.
## Installation
Maven:
```xml
<dependency>
<groupId>com.anthropic</groupId>
<artifactId>anthropic-java</artifactId>
<version>2.34.0</version>
</dependency>
```
Gradle:
```groovy
implementation("com.anthropic:anthropic-java:2.34.0")
```
## 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_8)
.maxTokens(16000L)
.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()));
```
---
## Thinking
**Adaptive thinking is the recommended mode for Claude 4.6+ models.** Claude decides dynamically when and how much to think. The builder has a direct `.thinking(ThinkingConfigAdaptive)` overload — no manual union wrapping.
> **Fable 5, Opus 4.8, Opus 4.7, Opus 4.6, and Sonnet 4.6:** Use adaptive thinking (below). `ThinkingConfigEnabled.builder().budgetTokens(N)` is removed on Fable 5, Opus 4.8, and 4.7 (400 if sent); deprecated on Opus 4.6 and Sonnet 4.6.
> **Older models:** Use `.thinking(ThinkingConfigEnabled.builder().budgetTokens(N).build())` (budget must be < `maxTokens`, min 1024).
```java
import com.anthropic.models.messages.ContentBlock;
import com.anthropic.models.messages.MessageCreateParams;
import com.anthropic.models.messages.Model;
import com.anthropic.models.messages.ThinkingConfigAdaptive;
MessageCreateParams params = MessageCreateParams.builder()
.model(Model.CLAUDE_SONNET_4_6)
.maxTokens(16000L)
.thinking(ThinkingConfigAdaptive.builder().build())
.addUserMessage("Solve this step by step: 27 * 453")
.build();
for (ContentBlock block : client.messages().create(params).content()) {
block.thinking().ifPresent(t -> System.out.println("[thinking] " + t.thinking()));
block.text().ifPresent(t -> System.out.println(t.text()));
}
```
`ContentBlock` narrowing: `.thinking()` / `.text()` return `Optional<T>` — use `.ifPresent(...)` or `.stream().flatMap(...)`. Alternative: `isThinking()` / `asThinking()` boolean+unwrap pairs (throws on wrong variant).
---
## Effort Parameter
Effort is nested inside `OutputConfig` — there is NO `.effort()` directly on `MessageCreateParams.Builder`.
```java
import com.anthropic.models.messages.OutputConfig;
.outputConfig(OutputConfig.builder()
.effort(OutputConfig.Effort.HIGH) // or LOW, MEDIUM, MAX
.build())
```
Combine with `Thinking = ThinkingConfigAdaptive` for cost-quality control.
---
## Prompt Caching
System message as a list of `TextBlockParam` with `CacheControlEphemeral`. Use `.systemOfTextBlockParams(...)` — the plain `.system(String)` overload can't carry cache control. For placement patterns and the silent-invalidator audit checklist, see `shared/prompt-caching.md`.
```java
import com.anthropic.models.messages.TextBlockParam;
import com.anthropic.models.messages.CacheControlEphemeral;
.systemOfTextBlockParams(List.of(
TextBlockParam.builder()
.text(longSystemPrompt)
.cacheControl(CacheControlEphemeral.builder()
.ttl(CacheControlEphemeral.Ttl.TTL_1H) // optional; also TTL_5M
.build())
.build()))
```
There's also a top-level `.cacheControl(CacheControlEphemeral)` on `MessageCreateParams.Builder` and on `Tool.builder()`.
Verify hits via `response.usage().cacheCreationInputTokens()` / `response.usage().cacheReadInputTokens()`.
---
## Token Counting
```java
import com.anthropic.models.messages.MessageCountTokensParams;
long tokens = client.messages().countTokens(
MessageCountTokensParams.builder()
.model(Model.CLAUDE_SONNET_4_6)
.addUserMessage("Hello")
.build()
).inputTokens();
```
---
## PDF / Document Input
`DocumentBlockParam` builder has source shortcuts. Wrap in `ContentBlockParam.ofDocument()` and pass via `.addUserMessageOfBlockParams()`.
```java
import com.anthropic.models.messages.DocumentBlockParam;
import com.anthropic.models.messages.ContentBlockParam;
import com.anthropic.models.messages.TextBlockParam;
DocumentBlockParam doc = DocumentBlockParam.builder()
.source(Base64PdfSource.builder().data(base64String).build())
// or .source(UrlPdfSource.builder().url("https://...").build())
.title("My Document") // optional
.build();
```
For **Files API** document references, use the beta path and beta types — see `files-api.md`: `BetaRequestDocumentBlock.builder().source(BetaFileDocumentSource.builder().fileId(id).build())`.
```java
.addUserMessageOfBlockParams(List.of(
ContentBlockParam.ofDocument(doc),
ContentBlockParam.ofText(TextBlockParam.builder().text("Summarize this").build())))
```
---
## Stop Details
When `stopReason()` is `"refusal"`, the response includes structured `stopDetails()`:
```java
response.stopDetails().ifPresent(details -> {
System.out.println("Category: " + details.category());
System.out.println("Explanation: " + details.explanation());
});
```
**Refusal fallbacks ({{FABLE_NAME}}) — opt in by default.** Fallbacks are opt-in: without them a refused request simply stops. New `{{FABLE_ID}}` code should include the server-side `fallbacks` parameter (beta header `server-side-fallback-2026-06-01`, fallback model `{{OPUS_ID}}`, on the beta messages call) by default. The exact Java builder methods (and the client-side middleware for providers without server-side support) are not documented here — WebFetch the Java SDK repo's `examples/` from `shared/live-sources.md`; full semantics in `shared/model-migration.md` → Migrating to {{FABLE_NAME}} → `refusal` stop reason.
---
## Error Type
`AnthropicServiceException` exposes `.errorType()` returning `Optional<ErrorType>` for programmatic error classification:
```java
try {
client.messages().create(params);
} catch (AnthropicServiceException e) {
e.errorType().ifPresent(type ->
System.out.println("Error type: " + type) // RATE_LIMIT_ERROR, OVERLOADED_ERROR, etc.
);
}
```
---