Thread: Guys, really need your help

I just don't know where to start, and what to do now, if you have some suggestions please help me out

Here is a problem:

Write a program that prints a chart to the screen showing the randomness of the random number generator. The program should prompt the user for a number and then call the random number generator this user inputted number of times. The program should then put the random numbers generated into ten "boxes" corresponding to each tenth of the range of the random numbers. ( If the random number generator behaves in a truly random fashion, each time you run the program the chart should look a little different reflecting the randomness of the random number generator.) After your program can do a chart with numbers, add the code to draw a graph that shows the numbers displayed as asterisks. Keep in mind that you have two System methods: System.out.println () and System.out.prin (). The first prints a new line and the second doesn't

A sample graph may look like this
Please enter the number of times that you would like to call the random numbers generator: 100
The chart showing 100 calls to the random number generator is:
0 - .1 **********
.1 -.2 ********
.2 -.3**********
.3 -.4*******
.4 -.5*****
.5 -.6**********
.6 -.7****
.7 -.8************
.8 -.9*******
.9-10 *******

double num = Math,random(); // gives a random number 0 <= num <1

Alright. I know how to do random numbers, but I don't get how to turn them into stars like in the output above... and if you write 100, it will show you 100 stars.. I really don't have an idea what to do. Here is my code:


import java.util.Scanner;
public class shapes
{
public static void main (String [] args)
{
Scanner scan = new Scanner(System.in);
int i = 0;
double num;
int input;
System.out.println("enter the number");
input = scan.nextInt();
System.out.println("Please, enter the number of times that you would like to call the random number generator: " +input);
System.out.println("The chart showing " +input+ " calls to the random number generator is:");

while(i<10)
{

System.out.println(Math.random() +i);
i++;
}
}
}

I got it, but for example if you wrote 100 as an input, how do the program knows how many *s are needed? How to make *s instead of just random numbers??

So I have to use if-else ?

Am I right using "while" instead of "for"? Sorry, I am just new to programming...

but what about double num = Math,random() ? Where do I have to use it?

what about double num = Math,random(); do I have to use it before loop?

Ok! I will try, but if I am wrong, sorry...

1. Understand what the program is supposed to do. ( I understand, but not so clearly as I should)
2. Initialize and declare the variables(I should declare about 10 variables. It means for each box 10 variables)
3. Definitely, I need a loop.(as you said, even 2 loops, but unfortunately, I don't know where I should to put the second one)
4. Create the random numbers inside the loop. (still it's not really clear where)
5. Use System.out.print() and System.out.println() methods.

If I skipped something, please tell me

I am not really sure about arrays. We didn't cover the topics about arrays though. Can you tell me more about it?
In the first loop we just put like

for(double num= Math.random(); num <= 10; num++)

right?

I don't know about second one yet...

so if I will use arrays, it should look like this?

import java.util.Scanner;
public class shapes
{

public static void main (String [] args)
{

Scanner scan = new Scanner(System.in);
int numberOfTimes;

int[] count = new int[10];
double n = Math.random();

System.out.println("enter the number");
numberOfTimes = scan.nextInt();

System.out.println("Please, enter the number of times that you would like to call the random number generator: " +numberOfTimes);
System.out.println("The chart showing " +numberOfTimes+ " calls to the random number generator is:");

while(numberOfTimes <= 10)
{

if( n < 0.1 ) count[0]++;
else if( n < 0.2 ) count[1]++;
else if( n < 0.3 ) connt[2]++;
else if( n < 0.4 ) connt[3]++;
else if( n < 0.5 ) connt[4]++;
else if( n < 0.6 ) connt[5]++;
else if( n < 0.7 ) connt[6]++;
else if( n < 0.8 ) connt[7]++;
else if( n < 0.9 ) connt[8]++;
else if( n < 1.0 ) connt[9]++;
}
}
}

Actually, you might possibly be able to use a for loop for that one, though the while should be kept as well.

for (int k = 1; k <=10; k++)
{


if ( n < 0.1k) count(k-1)++;


}

Also, you might want to keep changing n as it will keep the same value unless you put it in the while loop for the other 9 times.

Have another variable called numberOfTimes2 and also have it start out at 0.

Change the while loop to

while (numberOfTimes2 <= numberOfTimes)

if you're going to be scanning in the number of times and iterating through that many, which is what it appears you're doing.

What does this mistake mean:

Exception in thread "main" java.lang.ArrayIndexOutOfBoundsException… -3
at pratice.main(pratice.java:16)

it should work now.. I don't know why it does appear that way...

Alright! Here is my code:

import java.util.*;
public class Shapes
    {
    public static void main(String [] args)
         {
               Scanner S=new Scanner(System.in);
               System.out.println("Enter how many random numbers you want to generate");
               int N=S.nextInt();
               Random r = new Random();
               int []freq=new int[10];
 
               for(int i=0;i<10;i++)freq[i]=0;
 
               for(int i=0;i<N;i++)
                    {
                      int k=r.nextInt()%10;
                      freq[k]++;
                     }
               for(int i=0;i<10;i++)
                    { 
                      for(int j=0;j<freq[i];j++)System.out.print("*");
                      System.out.println();
                    }
 
         }
}