# Java functions that answer questions about text

One `Door` class over the C library, for Java 21. Each call returns its answer and its run facts.

## Install

| Channel | Note |
| --- | --- |
| `io.github.botassembly:thinkthen-jvm:VERSION` | The Maven coordinate. |
| `thinkthen-jvm-VERSION-TARGET.tar.gz` | The door, Kotlin and Scala JARs, from each release. |
| `thinkthen-c-VERSION-TARGET.tar.gz` | The C library it calls, from the same release. |

Set `THINKTHEN_API_KEY` in the environment.

## A first call

```
import static java.nio.charset.StandardCharsets.UTF_8;

import thinkthen.Door;
import thinkthen.Door.Outcome;

public class FirstCall {
    public static void main(String[] args) {
        try (var tt = new Door()) {
            var question =
                "Does the customer ask for a refund?";
            var isRefund = tt.decide(
                question,
                "Please refund my order. It arrived broken."
                    .getBytes(UTF_8));
            assert Door.outcome(isRefund.value())
                == Outcome.YES;

            var refund = "{\"decide\": \"" + question
                + "\", \"threshold\": \"0.2:0.8\"}";
            isRefund = tt.decide(
                refund,
                "I want to send this back."
                    .getBytes(UTF_8));
            assert Door.outcome(isRefund.value())
                == Outcome.NOT_SURE;
        }
    }
}
```

*Build and run it beside the unpacked archives, thinkthen-c/ and thinkthen-jvm/*

```
javac --enable-preview --release 21 \
    -cp thinkthen-jvm/thinkthen-door.jar \
    FirstCall.java
java --enable-preview -ea \
    --enable-native-access=ALL-UNNAMED \
    -Dthinkthen.library="$PWD/thinkthen-c/lib/libthinkthen.so" \
    -cp thinkthen-jvm/thinkthen-door.jar:. \
    FirstCall
```

Not sure comes back as `Outcome.NOT_SURE`. Branch on it and send those cases to a person.

## Run facts

`decide` returns a `TypedResult`. Its `value()` holds the answer, and its `facts()` holds this call's run facts as a `Map`.

## Errors

A failed call throws a `Door.NativeFailure`. Its `failure` names one of six `FailureKind` values, with the message and the retry flag.

## Settings and recording

`new Door(settingsJson)` takes the settings as JSON. `"record"` writes a recording to a folder. `"replay"` answers from that recording with no connection. The [Settings](/install/settings/) page lists every setting.

## Jev, Liquid d1 and Ollama from Java

Java reads its backend from the environment. Set `THINKTHEN_BACKEND` to the name below. Set the backend's key variable in the shell, and the same sample asks that backend.

| Backend | Name | Key variable |
| --- | --- | --- |
| [TypeSafe Jev](/install/backends/typesafe/) | `typesafe` | `TYPESAFE_API_KEY` |
| [Liquid d1](/install/backends/liquid/) | `liquid` | `LIQUIDAI_API_KEY`, then `LIQUID_API_KEY` |
| [Ollama](/install/backends/ollama/) | `ollama` | `OLLAMA_API_KEY`. A local address needs no key. |

*Ask TypeSafe Jev.*

```
export THINKTHEN_BACKEND=typesafe
export TYPESAFE_API_KEY=...
```

*Ask Liquid d1.*

```
export THINKTHEN_BACKEND=liquid
export LIQUIDAI_API_KEY=...
```

*Ask Ollama. This block names a second port, 11535, as the site's runs do. On the default port, leave THINKTHEN_BASE_URL out.*

```
export THINKTHEN_BACKEND=ollama
export THINKTHEN_BASE_URL=http://localhost:11535/v1
```

```
import static java.nio.charset.StandardCharsets.UTF_8;

import thinkthen.Door;
import thinkthen.Door.Outcome;

public class Backends {
    public static void main(String[] args) {
        try (var tt = new Door()) {
            var question =
                "Does the customer ask for a refund?";
            var brokenIsRefund = tt.decide(
                question,
                "Please refund my order. It arrived broken."
                    .getBytes(UTF_8));
            var thanksIsRefund = tt.decide(
                question,
                "Thanks for the quick help yesterday!"
                    .getBytes(UTF_8));
            assert Door.outcome(brokenIsRefund.value())
                == Outcome.YES;
            assert Door.outcome(thanksIsRefund.value())
                == Outcome.NO;
        }
    }
}
```

*Build and run it beside the unpacked archives, thinkthen-c/ and thinkthen-jvm/*

```
javac --enable-preview --release 21 \
    -cp thinkthen-jvm/thinkthen-door.jar \
    Backends.java
java --enable-preview -ea \
    --enable-native-access=ALL-UNNAMED \
    -Dthinkthen.library="$PWD/thinkthen-c/lib/libthinkthen.so" \
    -cp thinkthen-jvm/thinkthen-door.jar:. \
    Backends
```

The configuration file's `backend` names a default backend for every run. The [Configuration](/install/configuration/#configuration-file) page shows the file.

### OpenAI Decisions API from Java

OpenAI announced its Decisions API on 2026-09-29 in its [DevDay 2026 recap](https://openai.com/index/devday-2026-recap/). OpenAI has published no address, schema or price, so ThinkThen cannot call it. The [OpenAI Decisions API](/install/backends/openai/) page says what ThinkThen knows.

## What is different in Java

- The door calls the C library through Java 21's foreign function API. `javac` and `java` take `--enable-preview`.
- `-Dthinkthen.library` names the C library by its absolute path.
- `assert` runs only under `java -ea`.

On GitHub: [github.com/botassembly/thinkthen](https://github.com/botassembly/thinkthen)