$ printf 'Ankur\n30\n' | java src/ReadLn.java
Your name? Your age? Hello Ankur, 30 is a good age to learn Java.
no newline after this, newline after this

$ java src/IoInAnyClass.java
IO.println works in a normal class with no import

$ java src/StaticImportIO.java     (import static java.lang.IO.* makes the bare form work)
println without the IO. prefix, after import static java.lang.IO.*

$ java broken/NoIoPrefix.java     (JDK 27: same error as on 25)
broken/NoIoPrefix.java:2: error: cannot find symbol
    println("hello");
    ^
  symbol:   method println(String)
  location: class NoIoPrefix
1 error
error: compilation failed

$ printf '' | java src/ReadLn.java     (stdin closed: what does readln return?)
Your name? Your age? Hello null, null is a good age to learn Java.
no newline after this, newline after this