Summary

System.console() should return the JVM's Console instance only when both standard input and output are connected to a terminal

Problem

The current java.io.Console class description reads:

If this virtual machine has a console then it is represented by a unique instance
of this class which can be obtained by invoking the System.console() method.
If no console device is available then an invocation of that method will return null.

Thus, it is up to the implementation to determine under what conditions a Console instance is returned. In recent JDK releases, a JLine-based Console implementation is available, which provides a Console instance even when standard input and/or output is redirected. This behavior can be problematic for password prompts, as users may be unaware of where the prompt is shown or where their input is being sent.

Solution

Enforce the rule that System.console() returns null when standard input and/or output is redirected, and a Console instance should not be created in such cases.

Specification

N/A. This is a behavioral change only.