For what sort of documentation comments are ....in java ??

Answer 1

Apart from what ~ swim ~ said you can also provide more info using the doc-comments
Most of them start with a '@' with it's appropriate to name.
Some commonly used specifiers are @param (to give description about the parameters of a method), @returns (describes the return value), @throws, @see (adds the See also: XXXX to the documentation).
Real world example
/**
@param n specifies the number to get the result
@returns the factorial of the number
@see #anotherMethod()
This method returns the facotorial of a given number using the recursive method.
*/
public int f(int n) {
return n<2?1:f(n-1);
}