Summary

We propose to re-preview the Implicitly Declared Classes and Instance Main Methods again. In addition to the current state of the feature, we propose to add implicit imports for java.base module (using the proposed Module Imports, JDK-8315129), and a "simple-io" (exact name is TBD) using the separatelly proposed "Simple-IO" class, please see JDK-8305457.

Problem

More experience is needed with the implicitly declared classes and instance main methods.

The current experience from the last round of preview is twofold:

• it is difficult for the inexperienced users to import manually from various packages
• it is difficult for the inexperienced users to work with I/O.

Solution

The proposed solution is twofold:

• re-preview the existing feature for another release, without changes unless otherwise noted.
• add implicit imports for java.base and "simple-io" for the implicitly declared classes. This is similar to the long-term existing implicit import for java.lang, but the new implicit imports are only used for the implicitly declared classes. Note this aspect of the solution depends on the proposed Module Imports, JDK-8315129 and "simple-io" class, JDK-8305457, which are related, but not covered by this CSR.

Specification

The draft JLS and JVMS specifications are attached.

There are no corresponding API changes.