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Math.random array need help with my code  RSS feed

 
Brian-kurt Kibbler
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Okey this is what i got. It ourputs random numbers between 0 and 100 , 25 times and that's what i want so that part is done.
But after it have printed out this random numbers 25 times i want the program to select 5 of the outprinted numbers at random and then again print out these 5 selected random numbers from the list of 25.
Any help is greatly appreciated.
 
fred rosenberger
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So take it one step at a time.

You have a bunch of numbers. How would you pick one at random?
 
Tim Cooke
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Brian-kurt Kibbler wrote:It ourputs random numbers between 0 and 100 , 25 times
You sure about that? (Spoiler alert: it doesn't)

Brian-kurt Kibbler wrote:But after it have printed out this random numbers 25 times i want the program to select 5 of the outprinted numbers at random and then again print out these 5 selected random numbers from the list of 25.
Answer me this: Is there a difference between selecting 5 random numbers from a list of 25 random numbers, and just selecting 5 random numbers?
 
Brian-kurt Kibbler
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Im not sure actually as it is the first time that im working with a array.
Should i make another for loop simular to the first one but with a output ?
 
Brian-kurt Kibbler
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Ye i noticed it only outputs numbers between 0- 10 , and if i exchange the <100 to <1000 it only outputs numbers over 10 to 100.
How is this possible ?
 
Tim Cooke
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This is what your code is doing:

What you have created is a thing that counts the occurrence of each integer between 0 and 24 that is obtained from calling java.util.Random 100 times
 
Junilu Lacar
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Brian-kurt Kibbler wrote:
It ourputs random numbers between 0 and 100 , 25 times

Tim Cooke wrote:You sure about that? (Spoiler alert: it doesn't)

@Brian-kurt Kibbler: When in doubt, refer to the API JavaDocs: http://docs.oracle.com/javase/8/docs/api/java/util/Random.html#nextInt-int-

Which one did you want as your upper bound, 100 or 25? Which one did you use in your program?
 
Tim Cooke
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Junilu, take another look. It's worse than that. The Random.nextInt() call is not being used to choose what value to put in the array, it's being used to select the index of the array.

You want to do something like this:
 
Junilu Lacar
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Tim Cooke wrote:Junilu, take another look. It's worse than that. The Random.nextInt() call is not being used to choose what value to put in the array, it's being used to select the index of the array.

It's not too bad, actually. OP just didn't code what he said he wanted to do. The code right now reminds me of the game we call Sungka back home, you might otherwise know it as Mancala, except this version simulates dropping shells in random holes instead of going in sequence around the board.

OP just needs to understand how to do these tasks separately:

1. Generate a random number N
2. Do something N times
3. Pick out the Nth element of an array

If OP understands the mechanics of each one of these, then it's just a matter of combining them in just the right way to do what he wants to do.
 
It is sorta covered in the JavaRanch Style Guide.
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