Sorting an array with selection sort. - Java Data Structure

Java examples for Data Structure:Sort

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Description

Sorting an array with selection sort.

Demo Code

import java.security.SecureRandom;
import java.util.Arrays;

public class Main
{
   // sort array using selection sort
   public static void selectionSort(int[] data)              
   {/*from  w  ww.jav  a  2 s.  c  om*/
      // loop over data.length - 1 elements      
      for (int i = 0; i < data.length - 1; i++)
      {
         int smallest = i; // first index of remaining array

         // loop to find index of smallest element              
         for (int index = i + 1; index < data.length; index++)
            if (data[index] < data[smallest])             
               smallest = index;                                

         swap(data, i, smallest); // swap smallest element into position
         printPass(data, i + 1, smallest); // output pass of algorithm  
      }                                          
   } 

   // helper method to swap values in two elements
   private static void swap(int[] data, int first, int second)
   {
      int temporary = data[first]; // store first in temporary
      data[first] = data[second]; // replace first with second
      data[second] = temporary; // put temporary in second
   } 

   private static void printPass(int[] data, int pass, int index)
   {
      System.out.printf("after pass %2d: ", pass);

      // output elements till selected item
      for (int i = 0; i < index; i++)
         System.out.printf("%d  ", data[i]);

      System.out.printf("%d* ", data[index]); // indicate swap

      // finish outputting array
      for (int i = index + 1; i < data.length; i++)
         System.out.printf("%d  ", data[i]);

      System.out.printf("%n               "); // for alignment

      // indicate amount of array that?s sorted
      for (int j = 0; j < pass; j++)
         System.out.print("--  ");
      System.out.println(); 
   } 

   public static void main(String[] args)
   {
      SecureRandom generator = new SecureRandom();

      int[] data = new int[10]; // create array

      for (int i = 0; i < data.length; i++) // populate array
         data[i] = 10 + generator.nextInt(90);

      System.out.printf("Unsorted array:%n%s%n%n", 
         Arrays.toString(data)); // display array
      selectionSort(data); // sort array

      System.out.printf("Sorted array:%n%s%n%n", 
         Arrays.toString(data)); // display array
   } 
}

Result


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