blob: 079e649853815d9c4dabafb64855188c28d2d9ce [file] [view] [edit]
Null-checking `System.console()` is not a reliable way to detect if the console
is connected to a terminal.
See
[Release Note: JLine As The Default Console Provider](https://bugs.openjdk.org/browse/JDK-8309155):
> `System.console()` now returns a `Console` object when the standard streams
> are redirected or connected to a virtual terminal. In prior releases,
> `System.console()` returned `null` for these cases. This change may impact
> code that uses the return from `System.console()` to test if the VM is
> connected to a terminal. If needed, running with `-Djdk.console=java.base`
> will restore older behavior where the console is only returned when it is
> connected to a terminal.
> A new method `Console.isTerminal()` has been added to test if console is
> connected to a terminal.
To prepare for this change while remaining compatible with JDK versions prior to
JDK 22, consider using reflection to call `Console#isTerminal` on JDK versions
that support it:
```java
@SuppressWarnings("SystemConsoleNull") // https://errorprone.info/bugpattern/SystemConsoleNull
private static boolean systemConsoleIsTerminal() {
Console systemConsole = System.console();
if (Runtime.version().feature() < 22) {
return systemConsole != null;
}
try {
return (Boolean) Console.class.getMethod("isTerminal").invoke(systemConsole);
} catch (ReflectiveOperationException e) {
throw new LinkageError(e.getMessage(), e);
}
}
```