Can we instantiate an abstract class?

You can't directly instantiate an abstract class, but you can create an anonymous class when there is no concrete class:

public class AbstractTest {
public static void main(final String... args) {
final Printer p = new Printer() {
void printSomethingOther() {
System.out.println("other");
}
@Override
public void print() {
super.print();
System.out.println("world");
printSomethingOther(); // works fine
}
};
p.print();
//p.printSomethingOther(); // does not work
}
}

abstract class Printer {
public void print() {
System.out.println("hello");
}
}

This works with interfaces, too.