Question: Reference: [link text](http://download.oracle.com/javase/1.4.2/docs/api/java/util/Random.html)

i cannot understand the following line , can anybody provide me some example for the below statement?

If two instances of Random are created with the same seed, and the same sequence of method calls is made for each, they will generate and return identical sequences of numbers

Answer: 
The numbers are not really random, given the same starting conditions (the seed) and the same sequence of operations, the same sequence of numbers will be generated. This is why it would not be a good iea to use the basic Random class as part of any cryptograhic or security related code since it may be possible for an attacker to figure out which sequnce is being generated and predict future numbers.

For a random number generator that emits non-deterministic values, take a look at [SecureRandom](http://download.oracle.com/javase/1.4.2/docs/api/java/security/SecureRandom.html).

See [Random number generation, Computational methods](http://en.wikipedia.org/wiki/Random_number_generation#Computational_methods) on wikipedia for more info.
With the same seed value, separate instances of Random will return/generate the same sequence of random numbers; more on this here:
<http://www.particle.kth.se/~lindsey/JavaCourse/Book/Part1/Tech/Chapter04/javaRandNums.html>

Ruby Example:

```
class LCG; def initialize(seed=Time.now.to_i, a=2416, b=374441, m=1771075); @x, @a, @b, @m = seed % m, a, b, m; end; def next(); @x = (@a * @x + @b) % @m; end; end

irb(main):004:0> time = Time.now.to_i
=> 1282908389

irb(main):005:0> r = LCG.new(time)
=> #<LCG:0x0000010094f578 @x=650089, @a=2416, @b=374441, @m=1771075>
irb(main):006:0> r.next
=> 45940
irb(main):007:0> r.next
=> 1558831
irb(main):008:0> r.next
=> 1204687
irb(main):009:0> f = LCG.new(time)
=> #<LCG:0x0000010084cb28 @x=650089, @a=2416, @b=374441, @m=1771075>
irb(main):010:0> f.next
=> 45940
irb(main):011:0> f.next
=> 1558831
irb(main):012:0> f.next
=> 1204687

```

Based on the values a/b/m, the result will be the same for a given seed. This can be used to generate the same "random" number in two places and both sides can depend on getting the same result. This can be useful for encryption; although obviously, this algorithm isn't cryptographically secure.