Java Interop

ToC

• Using Faker DSL
• Calling Faker methods

Using Faker DSL

Even though kotlin-faker was created with Kotlin in mind, it is still possible to use this library from a Java-based project thanks to great Kotlin-to-Java interop.

Kotlin faker comes with a DSL-like functions (see also Faker DSL), and while this works great with Kotlin with its type inferences and implicit returns from lambdas, "functional Kotlin-to-Java" interoperability is far from nice.

To somehow mitigate these limitations, kotlin faker comes with a FunctionalUtils java class that has a static fromConsumer method which takes a function and returns the last statement, thus avoiding the need to specify the return explicitly.

Consider the following example of creating and configuring a Faker instance with the DSL:

Faker faker = faker(fromConsumer(f -> {
    f.config(fromConsumer(config -> {
        config.setRandomSeed(42L);
    }));
}));

This of course doesn't look as good as Kotlin, but that's Java for you with its ugly lambdas.

However, if builder parameters are not called with the help of fromConsumer method, then explicit returns should be specified:

Faker faker = faker(f -> {
    f.config(config -> {
        config.setRandomSeed(42L);
        return Unit.INSTANCE;
    });
    return Unit.INSTANCE;
});

Fewer parentheses, but an explicit return statement for each lambda - the choice, as they say, is yours.

Calling Faker methods

Calling a faker method is pretty straightforward. The only difference between kotlin and java here is that in java you need to call the getter of the fake data provider properties such as name, address, and so on.

faker.getName().firstName()
faker.getAddress().city()

faker.name.firstName()
faker.address.city()