It is common for people to name directories as dir1, dir2, and so on. When there

Question

It is common for people to name directories as dir1, dir2, and so on. When there are ten or more direct ories, the operating system displays them in dictionary order, as dir1, dir10, dir11, dir12, dir2, dir3, and so on. That is irritating, and it is easy to fix. Provide a comparator that compares strings that end in digit sequences in a way that makes sense to a human. First compare the part before the digit as strings, and then compare the numeric values of the digits. Your program should read in a text file with the list of directories to sort and should output them to the screen. If an error is found while reading the text file, the user should be allowed to choose another file. There will be one directory name per line of the file. Java, netBeans

Explanation / Answer

/*
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* To change this template file, choose Tools | Templates
* and open the template in the editor.
*/
package chegg.june;

import java.io.BufferedReader;
import java.io.FileNotFoundException;
import java.io.FileReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.util.logging.Level;
import java.util.logging.Logger;

/**
*
* @author Sam
*/
public class SortDir {
    String[] dirs;
    public static void main(String[] args) throws IOException {
        SortDir obj = new SortDir();
        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
        String location = "";
        while (!obj.loadDir(location)){
            System.out.println("CAnnot read file. Enter new location: ");
            location = br.readLine();
        }
        obj.sort();
        obj.print();
   }      
  
    private boolean loadDir(String location){
        try {
            BufferedReader br = new BufferedReader(new FileReader(location));
            int n = 0;
            while (br.readLine()!=null)
                n++;
            dirs = new String[n];
            br = new BufferedReader(new FileReader(location));
            String line;
            n = 0;
            while ((line = br.readLine())!=null)
                dirs[n++]=line;
            return true;
        } catch (FileNotFoundException ex) {
            Logger.getLogger(SortDir.class.getName()).log(Level.SEVERE, null, ex);
        } catch (IOException ex) {
            Logger.getLogger(SortDir.class.getName()).log(Level.SEVERE, null, ex);
        }
        return false;
      
    }
  
    private void sort() {
        String tmp;
        for (int i = 0; i < dirs.length; i++)
            for (int j = 0; j < dirs.length - i - 1; j++) {
                int a = 0, b = 0, pos = 0;
                //NOTE: 25 = 5 + 20 = 5*10^0 + 2*10^1
                for (int k = dirs[j].length()-1; k >= 0; k--) //extract the number from the right end of the string
                    if (dirs[j].charAt(k) >= '0' && dirs[j].charAt(k) <= '9')
                        a += (dirs[j].charAt(k) - '0') * Math.pow(10, pos++);
                    else
                        break;
              
                pos = 0; //reset pos which take care of the power
              
                for (int k = dirs[j+1].length()-1; k >= 0; k--) %repeat for j+1th string
                    if (dirs[j+1].charAt(k) >= '0' && dirs[j+1].charAt(k) <= '9')
                        b += (dirs[j+1].charAt(k) - '0') * Math.pow(10, pos++);
                    else
                        break;
                if (a > b) {
                    tmp = dirs[j];
                    dirs[j] = dirs[j+1];
                    dirs[j+1] = tmp;
                }
            }
    }
  
    private void print() {
        for (int i = 0; i < dirs.length; i++)
            System.out.println(dirs[i]);
    }
}

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