CODEWITHSUNDEEP
javaclassrandom
Asalas77
Asalas77

Reputation: 249

Difference between Random and RandomGenerator

Main class for this project is acm.program.GraphicsProgram; GraphicsProgram

When working on my project earlier i needed to randomize ball movement slightly in Pong game and found solution to this by using import java.util.Random; and then i used this code (executed every time ball bounces off player's paddle, this makes the ball move differently every game):

Random rand = new Random();
            boolean bool = rand.nextBoolean();
            if (bool)
                if (dx > 0)
                    dx += 1;
                else
                    dx -= 1;
            else if (dy > 0)
                    dy += 0.5;
                 else
                    dy -= 0.5;

where dx and dy are respectively ball horizontal and veritcal speeds.

But today during lecture on university we've been shown different method (not related to the 1st one, i figured that one myself earier), using

import acm.util.RandomGenerator;

and then

RandomGenerator rgen = RandomGenerator.getInstance();
boolean bool = rgen.nextBoolean();

Is there any difference between these two classes (Random and RandomGenerator)? If so, which one is better to use? I don't quite understand what getInstance(); is and why I didn't need one when using Random class.

Upvotes: 1

Views: 3720

Answers (1)

erickson
erickson

Reputation: 269847

The ACM RandomGenerator has a few extra conveniences methods, like nextColor() to pick a random color.

It also provides a global generator, via its getInstance() class method. Based on the comments, it sounds like the constructor uses the current time as a seed. This is a big flaw, and can result in a bug where different generator instances produce the same sequence of random numbers. To work around this, they recommend using just one instance of RandomGenerator, accessed via the getInstance() method.

In general, it would be best to use java.util.Random, because it doesn't introduce a third-party dependency in your program, and it uses a better seeding algorithm that isn't subject to the flaws of the ACM implementation.

Upvotes: 5

Related Questions