why does declaration of Sacnner ABC=new Scanner(); shows error in Java eclipse.?

Answer 1

Pass in "System.in"
Into the contructor of the class Scanner e.g
Scanner s = new Scanner(System.in);

Answer 2

you need an InputStream, a String, a File, a Readable, ... as an argument for the Scanner konstruktor.

For example System.in.

https://docs.oracle.com/javase/7/docs/api/java/util/Scanner.html