Java Compatibility¶

Coil's API is designed to be Kotlin-first. It leverages Kotlin language features such as inlined lambdas, receiver params, default arguments, and extension functions, which are not available in Java.

Importantly, suspend functions cannot be implemented in Java. This means custom Transformations, Size Resolvers, Fetchers, and Decoders must be implemented in Kotlin.

Despite these limitations, most of Coil's API is Java compatible. The Context.imageLoader extension function should not be used from Java. Instead, you can get the singleton ImageLoader using:

ImageLoader imageLoader = Coil.imageLoader(context)

The syntax to enqueue an ImageRequest is almost the same in Java and Kotlin:

ImageRequest request = new ImageRequest.Builder(context)
    .data("https://example.com/image.jpg")
    .crossfade(true)
    .target(imageView)
    .build();
imageLoader.enqueue(request)

suspend functions cannot be easily called from Java. Thus, to get an image synchronously you'll have to use the ImageLoader.executeBlocking extension function which can be called from Java like so:

ImageRequest request = new ImageRequest.Builder(context)
    .data("https://example.com/image.jpg")
    .size(1080, 1920)
    .build();
Drawable drawable = ImageLoaders.executeBlocking(imageLoader, request).getDrawable();