Java2ts

Java library with gradle plugin, which generates typescript types definitions from java classes. It requires java classes to be loaded in runtime. It does NOT support generation from non-compiled java source files.

Supports:

• fields (only instance, public),
• methods (only instance, public),
• inheritance,
• generics,
• functional interfaces as lambda types.

Use case

GraalVM interoperability feature can use Java objects in JavaScript environment (Doc). Unfortunately, seems there is no way to run TypeScript code in GraalVM directly.

Example

From:

class Child extends Parent<Long> {
    public Long childField;
}
class Parent<T> {
    public T parentField;
    public T[] method(String... args) { return null; }
}

To:

export declare interface Child extends Parent<number> {
    childField: number | null
}
export declare interface Parent<T> {
    parentField: T | null
    method(args: string[] | null): T[] | null
}

java2ts-core

Usage:

TsGenerator gen = new TsGenerator();
// sorting of type members (alphabetically), otherwise order is unpredictable
// default value: true
gen.setSortingEnabled(false);

// predicate for Class<?> class, return true if type should be processed (unsupported types will use 'any' type)
// default value: supports all except Object.class and Class.class
gen.setSupportedPredicate(t -> t.getPackageName().contains("java."));

// function which will be used to map Class objects to typescript type names
// default value: prefixes classes from 'java.*' package with 'J'
gen.setNameResolver(type -> "Prefix" + type.getSimpleName());

// register classes which you want generated
gen.registerType(YourCustomClass.class);

// get only registered types declarations
String out1 = gen.getRegisteredDeclarations();
// get all all types declarations which were processed transitively
String out2 = gen.getAllDeclarations();

java2ts-plugin

Usage in build.gradle file:

plugins {
    id 'java'
    id 'dev.harrel.java2ts' version '1.0'
}
// ...
generateTsDeclarations {
    // SourceSet from which output we want to load classes
    // default value: 'main' source set provided by 'java' plugin
    sourceSet = project.sourceSets.getByName('main')
    
    // fully qualified names of types you want to register for generation
    // default value: empty collection which means all types from source set output
    includeTypes = ['org.testing.Child']

    // fully qualified names of types you want to exclude
    // default value: empty collection
    excludeTypes = ['org.testing.Internal']

    // file to which declarations will be written
    // default value: ./build/generated/java2ts/types.d.ts
    output = project.layout.projectDirectory.file("custom.txt")
    
    // sorting of type members (alphabetically), otherwise order is unpredictable
    // default value: true
    sorting = false

    // predicate for Class<?> class, return true if type should be processed (unsupported types will use 'any' type)
    // please don't use stateful Closures to ensure its serializability
    // default value: supports all except Object.class and Class.class
    supportedPredicate = { type -> type.getPackageName().contains("java.") }
    
    // function which will be used to map Class objects to typescript type names
    // please don't use stateful Closures to ensure its serializability
    // default value: prefixes classes from 'java.*' package with 'J'
    nameResolver = { type -> type.getSimpleName() + 'xxx' }
    
    // determines if declarations for transitive types should also be generated
    // default value: true
    transitive = false
}