Here why it is throwing null point exception.
as we know that strings are immutable so there is no change in
string a .
so why it is not printing null.
but if i remove /////1 and //////2 then it prints null.
How ?/
public class NULL
{
public static void main (String[] args)
{
String a = null;
a.concat("abc");/////1
a.concat("def");/////2
System.out.println(a);
}
}