Building a Japanese Language Analysis Tool with Java, Kotlin, Spring Boot, and Gradle (Multi‑module Project)

This article introduces a personal project started in September of the author's first year of graduate school: a Japanese language analysis tool built with Java, Kotlin, Spring Boot, Gradle, and Swing. The author highlights three technical characteristics of the project: running a Swing UI inside a Spring Boot application, using a Gradle parent‑child multi‑module setup with Kotlin mixed in, and embedding a Chromium engine for displaying a personal website.

Technical stack : Java, Kotlin, Swing, Spring Boot, Gradle (KTS DSL), Lombok, RxJava, FastJSON2, Commons‑IO, and several UI libraries (FlatLaf, JTattoo). The runtime environment is JetBrains Runtime with JCEF (Java 21).

Parent module configuration – the root settings.gradle.kts declares all sub‑modules:

rootProject.name = "cable-car"

include(":1-common")
include(":1-reactivex")
include(":1-spring-application")
include(":2-jp-analysis-core")
include(":3-client-framework")
include(":4-web-jp-learning")

The root build.gradle.kts defines the Java version, plugins, repositories, and common tasks:

import org.jetbrains.kotlin.gradle.tasks.KotlinCompile

group = "com.hu.cablecar"
version = "0.0.1"
description = "缆车"

// Java version
java {
    sourceCompatibility = JavaVersion.VERSION_21
    targetCompatibility = JavaVersion.VERSION_21
}

// Plugins for Java, Kotlin, Lombok
plugins {
    java
    kotlin("jvm") version "1.9.24"
    kotlin("plugin.lombok") version "1.9.24"
    id("io.freefair.lombok") version "8.10"
}

// Repository configuration
allprojects {
    repositories {
        maven { url = uri("https://maven.aliyun.com/nexus/content/groups/public/") }
        mavenCentral()
        mavenLocal()
    }
    tasks.withType
{ options.encoding = "UTF-8" }
    tasks.withType
{ options.encoding = "UTF-8" }
    tasks.withType
{
        kotlinOptions { freeCompilerArgs = listOf("-Xjsr305=strict"); jvmTarget = "21" }
    }
}

The configuration performs three main actions: sets the Java version, applies Java/Kotlin/Lombok support to all sub‑modules, and configures Maven repository URLs.

Sub‑module overview :

1-common – a simple module containing three Java utility classes and a FastJSON2 dependency. description = "公共基础模块" dependencies { implementation("com.alibaba.fastjson2:fastjson2:2.0.45") }

1-reactivex – provides RxJava‑based publish/subscribe functionality and depends on 1-common . description = "RX" dependencies { implementation(project(":1-common")) implementation("io.reactivex.rxjava3:rxjava:3.1.9") }

2-jp-analysis-core – the core Japanese text analysis module, pulling in Commons‑IO and 1-common . description = "日语分析核心模块" plugins { } dependencies { implementation(project(":1-common")) implementation("commons-io:commons-io:2.15.1") }

3-client-framework – the main UI module that launches the Swing interface via Spring Boot, mixes Java and Kotlin, and bundles several UI JARs. It also declares all other sub‑modules as dependencies. description = "客户端UI框架" plugins { kotlin("plugin.spring") version "1.9.24" id("org.springframework.boot") version "3.3.4" id("io.spring.dependency-management") version "1.1.6" } dependencies { implementation(project(":1-common")) implementation(project(":1-reactivex")) implementation(project(":1-spring-application")) implementation(project(":2-jp-analysis-core")) implementation(project(":4-web-jp-learning")) implementation("org.springframework.boot:spring-boot-starter") implementation("org.springframework.boot:spring-boot-starter-web") implementation("org.springframework.boot:spring-boot-starter-tomcat") implementation("io.reactivex.rxjava3:rxjava") implementation("commons-io:commons-io:2.15.1") implementation(files("lib/ui/flatlaf-3.5.2.jar")) implementation(files("lib/ui/flatlaf-intellij-themes-3.5.2.jar")) implementation(files("lib/ui/JTattoo-1.6.13.jar")) } tasks.jar { enabled = true manifest { attributes(mapOf("Main-Class" to "com.hu.cablecar.client.framework.ClientFrameworkApplication")) } }

By focusing on the three Gradle files ( settings.gradle.kts , root build.gradle.kts , and each module's build.gradle.kts ), the author demonstrates that a complex multi‑module Java/Kotlin project can be configured concisely compared to an equivalent Maven setup.

The UI module embeds a Chromium engine to display the author's personal website (a Japanese learning blog), and the Swing interface is built with the author's own expertise.

In summary, the article provides a step‑by‑step guide to setting up a Gradle‑based parent‑child project that mixes Java and Kotlin, integrates Spring Boot, Swing, and Chromium, and shows how to package the application as a runnable JAR.