is System.in an object reference of InputStream class?

Question

InputStream is an Abstract class.Then how are we able to access System.in.And moreover int read() is an abstract method in InputStream class.Then how are we able to access S

Answer 1

is System.in an object reference of InputStream class?

yes!, it is declared/documented in the System class:

/**
 * The "standard" input stream. This stream is already
 * open and ready to supply input data. Typically this stream
 * corresponds to keyboard input or another input source specified by
 * the host environment or user.
 */
public final static InputStream in = null;

but at runtime is a reference to a BufferedInputStream class

so ou are not instantiating an abstract class