Java Module System

A named module has module-info.java, explicit dependencies, and strongly encapsulated packages.

Descriptor

module com.example.orders {
    requires java.sql;
    exports com.example.orders.api;
    opens com.example.orders.model to com.example.framework;
    uses com.example.orders.spi.PaymentProvider;
}

requires reads another module, exports exposes a package’s public types, and opens permits deep reflection. provides ... with ... registers service implementations. Compile and run named modules on the module path. Keep internal packages unexported, avoid cyclic dependencies and split packages, and use automatic modules only as a migration bridge.