Seed Value

[Micheal John]

From web page

Which of the following statements is true in terms of the java.lang.Math.random method? 
 
a.  The random method name is overloaded. 
b.  The argument type is a double that represents a seed value. 
c.  Throws an ArithmeticException if the seed value is negative. 
d.  The returned value is always greater than zero and less than or equal to one. 
e.  None of the above 

What is the seed value?

[Joe San]

I'd say the answer is d.

[Micheal John]

But answer is e.None of the above..
And also I want to know what is seed value?

[Bin Qian]

I think the answer is e.
because the random method is a static method.so it cann't be overloaded.and it has no argument, and the returned value is greater or equals to 0 and always less than 1.

[Barry Gaunt]

The question is very simply answered if you look at the Java API for Math.random. There you will see that there is only one double Math.random() method. So you do not even have to know for this question what a seed value is.

[Barry Gaunt]

Of course, you can always read Dan's own answers. He put a lot of effort into his questions and explanations, so spend time reading them, you can learn a lot.

[Burkhard Hassel]

Hi ranchers,

I could not find the solution page in the link provided from Michael (question #12).

Anyway, a seed is a starting value in generating pseudo random numbers.
If you specify the seed, all "random" numbers generated from this will appear in the same sequence.

But in Math.random() you cannot specify the seed, it is calculated from the system time in milliseconds.

You can however specify the seed in the java.util.Random class.
Example:

import java.util.Random;
 
class Main {
public static void main(String[] args) {
Random one = new Random(42L); // seed 42
Random two = new Random(42L); // same
Random three = new Random(-100L); // seed -100
System.out.printf("%7s%7s%7s%n","one","two", "three");
for (int i=0; i<10; i++){
System.out.printf("%7d%7d%7d%n", 
one.nextInt(100),
two.nextInt(100),
three.nextInt(100) );
}
}
 
}

The first two columns started with the same seed show the same "random" numbers.
Output is

    one    two  three
     30     30     86
     63     63     15
     48     48     27
     84     84     74
     70     70     19
     25     25     28
      5      5     95
     18     18     81
     19     19     64
     93     93     87

Seed is used when you want some control in your random numbers, eg when doing statistics or cheating in online poker games. For the last thing be sure your gun is faster, cowboys.


Yours,
Bu.

[Barry Gaunt]

@Bu: just go up in the directory and down into this

As I said before knowing what a seed is to 100% irrelevant to this question. Looking at the Math API is the important thing to learn to do.

[Bert Bates]

from the wet towel dept.:

This is clearly NOT a SCJP 5 topic and I think it's a little outside the scope of the 1.4 exam too.

[Burkhard Hassel]

Barry Gaunt posted December 08, 2006 05:03 AM

@Bu: just go up in the directory and down into this

thanks, found it.
Bu.