feat(java): java implementation of dotprompt

.github/workflows/java.yml

@@ -0,0 +1,62 @@
+# Copyright 2025 Google LLC
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+#
+# SPDX-License-Identifier: Apache-2.0
+
+name: Java checks
+
+on:
+  push:
+    branches:
+      - main
+    paths:
+      - "java/**"
+      - "spec/**"
+      - ".github/workflows/java.yml"
+  pull_request:
+    paths:
+      - "java/**"
+      - "spec/**"
+      - ".github/workflows/java.yml"
+
+jobs:
+  tests:
+    runs-on: ubuntu-latest
+    strategy:
+      matrix:
+        java-version: ['17', '21', '23', '24']
+      fail-fast: false
+
+    name: Java ${{ matrix.java-version }} Tests
+    steps:
+      - uses: actions/checkout@v4
+
+      - name: Set up JDK ${{ matrix.java-version }}
+        uses: actions/setup-java@v4
+        with:
+          java-version: ${{ matrix.java-version }}
+          distribution: 'temurin'
+
+      - name: Setup Bazel
+        uses: bazelbuild/setup-bazelisk@v3
+
+      - name: Run Tests
+        # Force Bazel to use the local JDK setup by actions/setup-java
+        run: |
+          bazel test \
+            --java_runtime_version=local_jdk \
+            --tool_java_runtime_version=local_jdk \
+            --test_output=errors \
+            //java/com/google/dotprompt:all \
+            //java/com/google/dotprompt/smoke:SmokeTest

.github/workflows/publish_java.yml

@@ -0,0 +1,69 @@
+# Copyright 2025 Google LLC
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+#
+# SPDX-License-Identifier: Apache-2.0
+
+name: Publish Java Package
+#
+# Requirements for this workflow:
+#
+# 1. Secrets must be configured in the repository settings:
+#    - OSSRH_USERNAME: The username for Sonatype OSSRH (Maven Central).
+#    - OSSRH_TOKEN: The password or token for Sonatype OSSRH.
+#    - MAVEN_GPG_PRIVATE_KEY: The ASCII-armored GPG private key for signing artifacts.
+#    - MAVEN_GPG_PASSPHRASE: The passphrase for the GPG private key.
+#
+# 2. GPG Key Formatting:
+#    - The private key should be exported using: `gpg --armor --export-secret-keys <ID>`
+#    - Ensure the key has no empty lines or formatting issues when pasted into GitHub Secrets.
+#
+
+on:
+  release:
+    types: [created]
+
+jobs:
+  publish-java:
+    runs-on: ubuntu-latest
+    permissions:
+      contents: read
+    steps:
+      - uses: actions/checkout@v4
+
+      - name: Set up JDK 21
+        uses: actions/setup-java@v4
+        with:
+          java-version: '21'
+          distribution: 'temurin'
+
+      - name: Setup Bazel
+        uses: bazelbuild/setup-bazelisk@v3
+
+      - name: Import GPG key
+        id: import_gpg
+        uses: crazy-max/ghaction-import-gpg@v6
+        with:
+          gpg_private_key: ${{ secrets.MAVEN_GPG_PRIVATE_KEY }}
+          passphrase: ${{ secrets.MAVEN_GPG_PASSPHRASE }}
+
+      - name: Publish to Maven Central
+        env:
+          MAVEN_USERNAME: ${{ secrets.OSSRH_USERNAME }}
+          MAVEN_PASSWORD: ${{ secrets.OSSRH_TOKEN }}
+        run: |
+          ./scripts/publish-java.sh \
+            "${{ steps.import_gpg.outputs.keyring }}" \
+            "${{ secrets.MAVEN_GPG_PASSPHRASE }}" \
+            "$MAVEN_USERNAME" \
+            "$MAVEN_PASSWORD"

MODULE.bazel

@@ -28,4 +28,5 @@ bazel_dep(name = "platforms", version = "1.0.0")
 include("//:go.MODULE.bazel")
 include("//:java.MODULE.bazel")
 include("//:rust.MODULE.bazel")
+include("//:kotlin.MODULE.bazel")
 include("//:ts.MODULE.bazel")

docs/contributing/coding_guidelines.md

@@ -7,6 +7,12 @@ You are an expert Python developer contributing to the Google Dotprompt project.
 - **Language**: Python.
 - **Environment Management**: Use `uv` for packaging and environment management.
 
+### Libraries
+- **JSON**: Use **Jackson** for JSON parsing and serialization. Avoid Gson.
+- **Testing**: Use **Google Truth** (`com.google.truth.Truth`) for assertions. Use JUnit 4/5 for test runners.
+- **Utilities**: Use **Guava** for immutable collections and common utilities.
+- **Dependency Injection**: Use **Dagger** for dependency injection.
+
 ## 2. Typing & Style
 - **Type Unions**: Use the pipe operator `|` (PEP 604) for union types (e.g., `int | str`) instead of `typing.Union`. Use `| None` for optional types.
 - **Generics**: Use standard collection generics (PEP 585) like `list`, `dict`, `tuple` (lowercase) for type hints instead of `typing.List`, `typing.Dict`.

java.MODULE.bazel

@@ -25,31 +25,19 @@ java_toolchain = use_repo_rule("@rules_java//java:repositories.bzl", "java_toolc
 
 java_toolchain(
     name = "jdk",
-    version = "21",
+    version = "17",
 )
 
 maven = use_extension("@rules_jvm_external//:extensions.bzl", "maven")
-
-# Overriding these versions to prevent duplicate version warnings.
-maven.artifact(
-    name = "guava",
-    artifact = "com.google.guava:guava:33.4.8-jre",
-    group = "com.google.guava",
-    version = "33.4.8-jre",
-)
-maven.artifact(
-    name = "truth",
-    artifact = "com.google.truth:truth:1.4.4",
-    group = "com.google.truth",
-    version = "1.4.4",
-)
 maven.install(
     artifacts = [
         "junit:junit:4.13.2",
         "com.google.truth.extensions:truth-proto-extension:1.4.4",
         "com.google.truth:truth:1.4.4",
         "com.github.jknack:handlebars:4.4.0",
-        "com.google.guava:guava:33.4.8-jre",
+        "com.google.guava:guava:33.5.0-jre",
+        "com.fasterxml.jackson.core:jackson-databind:2.20.1",
+        "com.fasterxml.jackson.dataformat:jackson-dataformat-yaml:2.20.1",
     ],
     lock_file = "//:maven_install.json",
     repositories = [

java.bazelrc

@@ -8,7 +8,12 @@ common:java21 --tool_java_language_version=21
 common:java21 --java_runtime_version=remotejdk_21
 common:java21 --tool_java_runtime_version=remotejdk_21
 
-common --config=java21
+common:java24 --java_language_version=24
+common:java24 --tool_java_language_version=24
+common:java24 --java_runtime_version=remotejdk_24
+common:java24 --tool_java_runtime_version=remotejdk_24
+
+common --config=java17
 
 # =============================================================================
 # junit_test is incompatible with JDK 18+ -

java/README.md

@@ -0,0 +1,50 @@
+# Deploying Java Dotprompt
+
+This document describes the process for releasing the `dotprompt` Java library to Maven Central.
+
+## Prerequisites
+
+1.  **GPG Keys**: You need a GPG key pair to sign artifacts.
+    *   Export the private key: `gpg --armor --export-secret-keys <ID>`
+    *   Note the passphrase.
+
+2.  **Sonatype OSSRH Account**: You need an account on [s01.oss.sonatype.org](https://s01.oss.sonatype.org/) (or the legacy server) with access to the `com.google.dotprompt` group ID.
+
+## GitHub Configuration
+
+Configure the following secrets in the GitHub repository settings:
+
+*   `OSSRH_USERNAME`: Your Sonatype username.
+*   `OSSRH_TOKEN`: Your Sonatype password or user token.
+*   `MAVEN_GPG_PRIVATE_KEY`: The ASCII-armored GPG private key.
+*   `MAVEN_GPG_PASSPHRASE`: The passphrase for your GPG key.
+
+## Release Process
+
+The release process is automated via GitHub Actions (`.github/workflows/publish_java.yml`).
+
+1.  **Create a Release**:
+    *   Go to the "Releases" section on GitHub.
+    *   Draft a new release.
+    *   Create a new tag (e.g., `v0.1.0`).
+    *   Publish the release.
+
+2.  **Automation**:
+    *   The `Publish Java Package` workflow will trigger automatically.
+    *   It sets up the JDK and Bazel environment.
+    *   It imports the GPG key.
+    *   It runs `scripts/publish-java.sh`, which invokes `bazel run //java/com/google/dotprompt:dotprompt_pkg.publish`.
+
+3.  **Verification**:
+    *   Check the workflow run logs for success.
+    *   Log in to Sonatype OSSRH to verify the staging repository if auto-release is not enabled, or check Maven Central (after a sync delay) if it is.
+
+## Local Testing (Dry Run)
+
+To verifying the build artifacts locally without publishing:
+
+```bash
+bazel build //java/com/google/dotprompt:dotprompt_pkg
+```
+
+This ensures the POM and JARs are correctly generated.

java/com/google/dotprompt/BUILD.bazel

@@ -13,3 +13,90 @@
 # limitations under the License.
 #
 # SPDX-License-Identifier: Apache-2.0
+
+load("@rules_java//java:defs.bzl", "java_library", "java_test")
+load("@rules_jvm_external//:defs.bzl", "java_export")
+
+java_library(
+    name = "dotprompt",
+    srcs = [
+        "Dotprompt.java",
+        "Helpers.java",
+        "PromptLoader.java",
+    ],
+    visibility = ["//visibility:public"],
+    deps = [
+        "//java/com/google/dotprompt/models",
+        "//java/com/google/dotprompt/parser",
+        "//java/com/google/dotprompt/resolvers",
+        "//java/com/google/dotprompt/store",
+        "@maven//:com_fasterxml_jackson_core_jackson_annotations",
+        "@maven//:com_fasterxml_jackson_core_jackson_core",
+        "@maven//:com_fasterxml_jackson_core_jackson_databind",
+        "@maven//:com_fasterxml_jackson_dataformat_jackson_dataformat_yaml",
+        "@maven//:com_github_jknack_handlebars",
+        "@maven//:com_google_guava_guava",
+    ],
+)
+
+java_export(
+    name = "dotprompt_pkg",
+    maven_coordinates = "com.google.dotprompt:dotprompt:0.1.0",
+    pom_template = "pom_template.xml",
+    visibility = ["//visibility:public"],
+    runtime_deps = [":dotprompt"],
+)
+
+java_test(
+    name = "DotpromptTest",
+    srcs = ["DotpromptTest.java"],
+    test_class = "com.google.dotprompt.DotpromptTest",
+    deps = [
+        ":dotprompt",
+        "//java/com/google/dotprompt/models",
+        "@maven//:com_google_guava_guava",
+        "@maven//:com_google_truth_truth",
+        "@maven//:junit_junit",
+    ],
+)
+
+java_test(
+    name = "SpecTest",
+    srcs = ["SpecTest.java"],
+    data = ["//spec"],
+    test_class = "com.google.dotprompt.SpecTest",
+    deps = [
+        ":dotprompt",
+        "//java/com/google/dotprompt/models",
+        "@maven//:com_fasterxml_jackson_core_jackson_databind",
+        "@maven//:com_fasterxml_jackson_dataformat_jackson_dataformat_yaml",
+        "@maven//:com_google_guava_guava",
+        "@maven//:com_google_truth_truth",
+        "@maven//:junit_junit",
+    ],
+)
+
+java_test(
+    name = "PromptLoaderTest",
+    srcs = ["PromptLoaderTest.java"],
+    test_class = "com.google.dotprompt.PromptLoaderTest",
+    deps = [
+        ":dotprompt",
+        "//java/com/google/dotprompt/models",
+        "@maven//:com_google_truth_truth",
+        "@maven//:junit_junit",
+    ],
+)
+
+java_test(
+    name = "HelpersTest",
+    srcs = ["HelpersTest.java"],
+    test_class = "com.google.dotprompt.HelpersTest",
+    deps = [
+        ":dotprompt",
+        "//java/com/google/dotprompt/models",
+        "@maven//:com_github_jknack_handlebars",
+        "@maven//:com_google_truth_truth",
+        "@maven//:junit_junit",
+    ],
+)