Thread: Beginner Coding problem in a class taught by professor with limited English comprehension

Hello, I have been taking a cs 2010 class and have finally gotten to start coding in Java. However, my professor cannot speak or write English very well so I am having to learn mostly by myself.
He recently sent us a project in which we have to:

1. Write a program that will use an array to store 10,000 randomly generated
numbers (ranging from 1 to 10,000 with no repeating numbers)

2. Using the selection sort algorithm to sort the number in ascending order, display the sorted sequence, each line showing just one number.

I have discovered that I will need to presumably generate the array with the 10,000 numbers, shuffle them, and then sort them.
However, I am completely lost on how to fill the array with the 10,000 numbers to begin with. I only know how to randomly fill them, but by doing that, I have repeating numbers.

Here is a snippet of what I have tried so far with no clue as to how to go from there. I thought I could write a while loop that would fill each one with (sum = 1+ sum), but I am not sure of the syntax or if that is even possible with arrays. Any help would be oh so helpful.

package array.sorter.project;
 
import java.util.*;
import java.util.Arrays;
 
 
public class Sorting {
	//generating 10000 spots in the array
	public static void main(String args[]){
	int[] tenthousand = new int[10000];
 
	//loop to add 1 to x and set the new value of x to the array spot
	int sum = 0;
	while ( sum < 10000){
			 sum = sum + 1;
	Arrays.fill(tenthousand, sum);
	}
 
 
 
	  for (int i = 0; i < tenthousand.length; i++) {
		  int smallestNo = tenthousand[i];
		  int posWithSmallest = i;
		  for (int j = i+1; j < tenthousand.length; j++) {
		    int val = tenthousand[j];
		    if (val < smallestNo) {
		      smallestNo = val;
		      posWithSmallest = j;
		    }
		  }
		  int tmp = tenthousand[i];
		  tenthousand[i] = smallestNo;
		  tenthousand[posWithSmallest] = tmp;
 
 
	}
 
 
	for (int i = 0; i < tenthousand.length; i++) {
		  System.out.println("Position " + i + " : " + tenthousand[i]);
		}
 
 
 
		}
 
}

I apologize in advance in any of this is terribly written or just completely wrong. As I said, I have no clue.

I have discovered that I will need to presumably generate the array with the 10,000 numbers, shuffle them, and then sort them.
However, I am completely lost on how to fill the array with the 10,000 numbers to begin with. I only know how to randomly fill them, but by doing that, I have repeating numbers.

Are you sure the array is supposed to contain 10,000 numbers?

If so, and you didn't want any repeats, you wouldn't fill them with random numbers - you would fill them with the numbers 1->10,000 (that takes care of having no repeats) then shuffle them (that provides the randomness). What I'm thinking is that sorting the resulting array would be a bit pointless in this case as you know in advance what the result would be.

I agree completely but that's exactly what the instructions say. I don't know. How does one go about filling the array with the numbers?

How does one go about filling the array with the numbers?

You are making it too complicated with that while loop and the fill() thing. Use a for loop. In fact it will be a for loop that looks a lot like the one at the end that you use to print the contents of the array. Instead of printing each element you assign a value to each element:

for (int i = 0; i < tenthousand.length; i++) {
    tenthousand[i] = ...
}

Break the problem up and tackle and test each problem.

1. How do we generate a random number between 1 and 10,000?
2. Create an array to hold 10,000 numbers.
3. How do I store only unique values? Do I filter them before filling the array or after? What tools are there in the API to help me?
4. Look up the required "selection sort" algorithm and make sure I know how it works. Implement a sort method and test it.
etc..