Solved

JAVA CODE CLARIFICATION

Posted on 2008-10-24
9
207 Views
Last Modified: 2013-11-23
Here is my script that works.  I need to have the numbers, when generated, not be duplicated.  I understand that I should use an array, but I do not know how.  Some clarification would be appreciated.  Thank you.

import java.util.Random;
public class Math
{
   public static void main ( String args[] )
   {
      Random randomNumbers = new Random();
      int number;
      for ( int counter = 1; counter <= 30; counter++)
      {
         number = 1 + randomNumbers.nextInt( 49 );
         System.out.printf("%d   ", number);
         if ( counter % 6 == 0 )
            System.out.println();
      }
   }
}
0
Comment
Question by:suekathur
[X]
Welcome to Experts Exchange

Add your voice to the tech community where 5M+ people just like you are talking about what matters.

  • Help others & share knowledge
  • Earn cash & points
  • Learn & ask questions
  • 5
  • 4
9 Comments
 
LVL 16

Accepted Solution

by:
sh0e earned 125 total points
ID: 22801527

import java.util.Random;
public class Math
{
   public static void main ( String args[] )
   {
      Random randomNumbers = new Random();
      int number;
bool[] oldnums = new int[50];
      for ( int counter = 1; counter <= 30; counter++)
      {
while(oldnums[number]){number = 1 + randomNumbers.nextInt( 49 );}
 
         System.out.printf("%d   ", number);
         if ( counter % 6 == 0 )
            System.out.println();
      }
   }
}

Open in new window

0
 

Author Comment

by:suekathur
ID: 22803659
The way I read the code is that you want to use a boolean stating that oldnums will equal a new integer and if the old number equals the same number then continue with the random number selection.  Am I reading this right?
I also tried running the new code and it does not work so I know things are missing.  Can you point me in the right direction, please.  Thanks
0
 
LVL 16

Assisted Solution

by:sh0e
sh0e earned 125 total points
ID: 22804043
Correct.  It's the easiest  way.  Just two lines.

I made a typo, it's boolean not bool.

import java.util.Random;
public class Math
{
   public static void main ( String args[] )
   {
      Random randomNumbers = new Random();
      int number;
boolean[] oldnums = new int[50];
      for ( int counter = 1; counter <= 30; counter++)
      {
while(oldnums[number]){number = 1 + randomNumbers.nextInt( 49 );}
 
         System.out.printf("%d   ", number);
         if ( counter % 6 == 0 )
            System.out.println();
      }
   }
}

Open in new window

0
The Ultimate Checklist to Optimize Your Website

Websites are getting bigger and complicated by the day. Video, images, custom fonts are all great for showcasing your product/service. But the price to pay in terms of reduced page load times and ultimately, decreased sales, can lead to some difficult decisions about what to cut.

 

Author Comment

by:suekathur
ID: 22804150
When running the code I get the following error:
incompatible types
found: int[]
required: boolean[]
boolean[] oldnums = new int[50];
I know that the boolean will need to be changed to a string and I have looked on the internet for possible solutions but I do not understand their reasoning.  I found this:  String myString = Integer.toString(my int value).









0
 
LVL 16

Assisted Solution

by:sh0e
sh0e earned 125 total points
ID: 22804234
Sorry, I don't know what got into me.  I initialized the boolean array wrong.
import java.util.Random;
public class Math
{
   public static void main ( String args[] )
   {
      Random randomNumbers = new Random();
      int number;
boolean[] oldnums = new boolean[50];
      for ( int counter = 1; counter <= 30; counter++)
      {
while(oldnums[number]){number = 1 + randomNumbers.nextInt( 49 );}
 
         System.out.printf("%d   ", number);
         if ( counter % 6 == 0 )
            System.out.println();
      }
   }
}

Open in new window

0
 

Author Comment

by:suekathur
ID: 22804403
Receiving the error: variable number might not have been initialized
while(oldnums[number]){number = 1 + randomNumbers.nextInt( 49 );}
the error happens under the [number] in the code.
Since the number has been intialized as an int number in the above code I do not know whyI am getting this.
0
 
LVL 16

Assisted Solution

by:sh0e
sh0e earned 125 total points
ID: 22804457

import java.util.Random;
public class Math
{
   public static void main ( String args[] )
   {
      Random randomNumbers = new Random();
      int number;
boolean[] oldnums = new boolean[50];
      for ( int counter = 1; counter <= 30; counter++){
         do{number = 1 + randomNumbers.nextInt( 49 );}while(oldnums[number]);
 
         System.out.printf("%d   ", number);
         if ( counter % 6 == 0 )
            System.out.println();
      }
   }
}

Open in new window

0
 

Author Comment

by:suekathur
ID: 22804743
This still does not work.  I am going to try a different method - maybe two arrays instead of one.
Consider this closed.
Thanks for your help.
0
 

Author Closing Comment

by:suekathur
ID: 31509891
Thank you for your help.  This is getting too complicated for me to understand so I am going to try something else.  It was suggested utilizing two arrays instead of one so I will try that,
0

Featured Post

Online Training Solution

Drastically shorten your training time with WalkMe's advanced online training solution that Guides your trainees to action. Forget about retraining and skyrocket knowledge retention rates.

Question has a verified solution.

If you are experiencing a similar issue, please ask a related question

For beginner Java programmers or at least those new to the Eclipse IDE, the following tutorial will show some (four) ways in which you can import your Java projects to your Eclipse workbench. Introduction While learning Java can be done with…
Basic understanding on "OO- Object Orientation" is needed for designing a logical solution to solve a problem. Basic OOAD is a prerequisite for a coder to ensure that they follow the basic design of OO. This would help developers to understand the b…
Viewers will learn about arithmetic and Boolean expressions in Java and the logical operators used to create Boolean expressions. We will cover the symbols used for arithmetic expressions and define each logical operator and how to use them in Boole…
Viewers will learn how to properly install Eclipse with the necessary JDK, and will take a look at an introductory Java program. Download Eclipse installation zip file: Extract files from zip file: Download and install JDK 8: Open Eclipse and …

734 members asked questions and received personalized solutions in the past 7 days.

Join the community of 500,000 technology professionals and ask your questions.

Join & Ask a Question