static final int[] wont print unsorted column

[Jesse Crockett]

I'm sorry to post the whole class, but I don't know how to reduce this correctly. The problem is the printSortedScreen method, which is supposed to print the unsorted column first, then the sorted column, but it actually prints both columns sorted. I don't know what I've done wrong..

import java.io.*;
 
public class SortList {
 
static final int[] LIST =
{42,468,335,1,170,225,479,359,463,465,206,146,282,329,462,492,496,443,328,437};
 

 
public static void main(String[] args) throws FileNotFoundException {
 
int[] sorted = selectionSort(LIST, LIST.length);
writeSorted(sorted);
printSortedScreen(LIST, sorted);
}
 

 
public static int[] selectionSort(int[] toSort, int listLength) {
 
int index;
int smallestIndex;
int minIndex;
int temp;
 
for(index = 0; index < listLength - 1; index++) {
 
smallestIndex = index;
 
for(minIndex = index + 1; minIndex < listLength; minIndex++)
 
if(toSort[minIndex] < toSort[smallestIndex])
smallestIndex = minIndex;
 
temp = toSort[smallestIndex];
toSort[smallestIndex] = toSort[index];
toSort[index] = temp;
}
 
int i;
int[] sortedList = new int[listLength];
for(i = 0; i < listLength; i++)
sortedList[i] = toSort[i];
 
return sortedList;
}
 
public static void writeSorted(int[] list1) throws FileNotFoundException  {
 
int i;
String listStr = "";
 
for(i = 0; i < list1.length; i++)
listStr += list1[i] + "\n";
 
PrintWriter toFile = new PrintWriter("prizeNos.srt");
toFile.write(listStr);
toFile.close();
}
 
public static void printSortedScreen(int[] unsorted, int[] sorted1) {
 
int i;
 
for(i = 0; i < unsorted.length; i++)
System.out.println(unsorted[i] + "\t\t" + sorted1[i]);
 
System.out.println("unsorted\tsorted");
}
}

[Keith Lynn]

The problem is with this method

public static int[] selectionSort(int[] toSort, int listLength) {

The first parameter is an object reference. When you sort the array named toSort inside the method, it sorts the array referred to by the parameter you send.

What you need to do is something like create a temporary array inside the method and copy the contents of the array to be sorted into it. Then sort that array instead of the array referred to by toSort.

Making the array reference final does not prevent the elements in the array from being changed. It prevents the array name from pointing to another array.

For example, this works with no problem

import java.util.*;
 
public class Test7 {
   static final int[] numbers = {1,2,3,4};
  
   public static void main(String[] args) {
      for (int number : numbers)
         System.out.println(number);
 
      numbers[0] = 5;
      numbers[1] = 8;
      numbers[2] = 7;
      numbers[3] = 6;
 
      for (int number : numbers)
         System.out.println(number);
   }
}

, but this causes a compile-time error.

import java.util.*;
 
public class Test7 {
   static final int[] numbers = {1,2,3,4};
  
   public static void main(String[] args) {
      for (int number : numbers)
         System.out.println(number);
 
      numbers[0] = 5;
      numbers[1] = 8;
      numbers[2] = 7;
      numbers[3] = 6;
 
      for (int number : numbers)
         System.out.println(number);
 
      numbers = new int[]{5,8,7,6};
   }
}

[ February 17, 2006: Message edited by: Keith Lynn ]

[Jesse Crockett]

My heart is broken that final doesn't work the way I thought. But of course it doesn't, no matter how much I say "but I *did* push the jump button"

 
//changes made:
public static int[] selectionSort(int[] toSort1, int listLength) {
 
int[] toSort = new int[listLength];
 
int a;
for(a = 0; a < listLength; a++)
toSort[a] = toSort1[a];
 
//continue sorting.. output is corrected   

[ February 17, 2006: Message edited by: Jesse Crockett ]