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Solve : Help with Java Random Class for Double values 0-100?

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Hello,  I am working on a class assignment for my Computer Science class  I have been working on it this week and it is due Sunday and I am not able to discuss this with my instructor.  This is part of a larger assignment and this is the part I am questioning.

The instructions say:

      The cost of a given ROCKETSHIP will be in billions of space credits.  The number
should be displayed using a DecimalFormat object.  Print the number of billions of space
credits just like you would print dollars and cents.  (For instance, 5.75 billion space
credits.)  The price of a rocketship will be between 3 and 20 billion space credits.  To
determine the price of a given rocketship, generate a random double between 0 and 100. If this number is less than 3.0, REPLACE its value with 3.0.  If the randomly-generated
number is greater than 20.0, replace its value with 20.0.  Then use whatever number you arrive at (between 3.0 and 20.0) as the rocketship’s price.   

Here is the output I get:

"Rocketship "Bob" costs 20.00 billion space credits."

Here is sample output:

"Rocketship "Ohio" costs 14.71 billion space credit"

"Rocketship "Illinois" costs 20.00 billion space credit"


I'm not SURE if this correct way to do this assignment

Here is the code I wrote:

            //Randomly give the cost of the ships from  a vaule of 0 to 100 
            costRandom = randomNumbers.nextInt(101);
         
          //If this number is less than 3.0, replace its value with 3.0.
          if (costRandom<3.0)
          {
              costRandom=3.0;
          }
             
          //If the number is greater than 20.0, replace its value with 20.0.   
          else if (costRandom>20.0)
          {
             costRandom=20.0;
          }


I tried:

        costRandom = randomNumbers.nextDouble(101);

and it said there needs to be no arguments



The problem is it only seems to print out just INTEGER values and not doubles.


I understand if you feel you shouldn't help because it a school assignment.

Let me know if you need to see the full code to understand.  Thank you for any help you can give.  This is Java?
Quote
randomNumbers.nextDouble
Looks like NET 4 instead.

But in Java one would see
Quote
Random rand = new Random();
Early in the code.
Did I miss something?I am new to Java and may have made a mistake. I will show what I did.


      // Create a Random object.
      Random randomNumbers = new Random();

      // Create a DecimalFormat object.   
      DecimalFormat formatter = new DecimalFormat("0.00");

      double costRandom;           //Holds the cost of the ships

          //Randomly give the cost of the ships from  a vaule of 0 to 100 
          costRandom = randomNumbers.nextInt(101);
         
          //If this number is less than 3.0, replace its value with 3.0.
          if (costRandom<3.0)
          {
              costRandom=3.0;
          }
             
          //If the number is greater than 20.0, replace its value with 20.0.   
          else if (costRandom>20.0)
          {
             costRandom=20.0;
          }
         
           (earlier in the program I ask the user for  a name)
          //Display Rocketship name ands its cost
          System.out.println("Rocketship \"" + r.Name +"\" costs " + formatter.format(costRandom) + " billion space credits.");

Right  now it is outputting a integer value   for "costRandom" and I need it to output a double value so it have the ability to give both a integer and two decimal places in the output.   I don't know how to turn it into a double.It would be nice to have a thing that souled just convert a integer into a  double.

I don't   know the elegant way to do it, being that I am so lazy and In don't want to do a lot of research, I might just do this.
Have an item that already is a double. Call  it mydouble
get the inter form the random thing 0 - 100 call it myinteger

now say something like this:
add myinteger to itself 5 times. Use a tmp if you wish.
Now say
mydouble = myinteger /5

dividing an integer forces a offloading point do-da-do.
You have a real number in mydouble.

Yeah, I know, not very elegant.
First get it to work. Polish it later.
Code: [Select]costRandom  = (randomNumbers.nextDouble()*17)+3;

Edit, Oh, I see they don't want you to do that.


Code: [Select]costRandom  = (randomNumbers.nextDouble()*100);
if(costRandom > 20)
 costRandom =20;
else if(costRandom < 3)
 costRandom=3;

Or you want to be unnecessarily terse...
Code: [Select]costRandom  = (randomNumbers.nextDouble()*100);
costRandom = costRandom > 20 ? 20 : costRandom < 3 ? 3 : costRandom;
Quote from: Geek-9pm on October 22, 2011, 12:52:39 AM
It would be nice to have a thing that souled just convert a integer into a  double.

Code: [Select]double doublevalue = (int)intvalue;

Quote
mydouble = myinteger /5

dividing an integer forces a offloading point do-da-do.
You have a real number in mydouble.
As you said, you didn't do any research. the division in that expression would be integer division. dividing by 5.0 would force the literal to be a double, I think, thus making the division a floating point operation.Thanks, BC
It is very hard for me to do research. I just use what I can.Thank you very much BC.

The code you suggested below works great for what I needed to do. 

costRandom  = (randomNumbers.nextDouble()*100);

if(costRandom > 20)
 costRandom =20;
else if(costRandom < 3)
 costRandom=3;


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