Generating random numbers, adding them to an array, and then sorting them using bubble sort

Question

I am attempting to randomly generate 10 numbers between 1 and 100, store them in an array, and then sort them using the bubble sort method included below. I am confident in the random number generation and storage, as well as the bubble sorting code. I am simply having an issue calling the bubbleSort method and printing the output. Please advise.

package chpt7_project;

import java.util.Arrays;



public class Chpt7_Project {

public static void main(String[] args) {
    // TODO Auto-generated method stub
        //Initialize array containing 10 numbers
        int[] list = new int[10];       

        //Generate 10 random numbers in the range of 1 - 100
        for(int i = 0; i < list.length; i++) {
          list[i] = (int)(Math.random()*100 + 1);
        } //End loop


        //Print output
        System.out.println("Generated unsorted list: " + Arrays.toString(list));
        System.out.println("Bubble Sorted Numbers:" + Arrays.toString(bubbleSort(list)));
}


//BubbleSort method provided by textbook
public static void bubbleSort(int[] list) 
  {
    int temp;

      for (int i = list.length - 1; i > 0; i--) 
      {
         for (int j = 0; j < i; j++) 
         {
           if (list[j] > list[j + 1]) 
           {
           temp = list[j];
           list[j] = list[j + 1];
           list[j + 1] = temp;
           }
         }
      }
   }
}

Answer 1

Your bubbleSort method will sort the array in place, ie it will change the existing array. Also, it has a void return type, so you cannot pass it as a parameter to Arrays.toString .

I believe you need to replace this line:

System.out.println("Bubble Sorted Numbers:" + Arrays.toString(bubbleSort(list)));

with these two lines:

bubbleSort(list);
System.out.println("Bubble Sorted Numbers:" + Arrays.toString(list));

This way you sort the array first with a call to bubbleSort , and then you pass the same list (which has now been modified by bubbleSort ) to Arrays.toString .

Answer 2

Your bubblesort is of type void and does not return anything. try to change void to int[] and return your list.

therefore no value is passed inside your toString method.

Arrays.toString(bubbleSort(list)));

try doing something like this:

public static int[] bubbleSort(int[] list)
  {
    int temp;

  for (int i = list.length - 1; i > 0; i--)
  {
     for (int j = 0; j < i; j++)
     {
       if (list[j] > list[j + 1])
       {
       temp = list[j];
       list[j] = list[j + 1];
       list[j + 1] = temp;
       }
     }
  }
  return list;
}