Random numbers in C++ vs Java

I have been using this in Java and I know what it produces:

Random r = new Random(); 
double mynum = r.nextDouble();

Whereas, I found this code in C++ which I wanted to use in Java:

srand(time(NULL));
double mynum = (double)rand() / RAND_MAX; 

Are these both equal?

If no, then what would be the equivalent java code?

where equivalent means produce a similar sequence of numbers? And my scientific computation will not be affected by this conversion.

I was assuming both as the same thing, not sure...