import java.io.BufferedWriter;
import java.io.File;
import java.io.FileWriter;
import java.io.IOException;
import java.util.Random;

public class CSV2 {

    public static void main(String[] args) throws IOException {
        long t0 = System.currentTimeMillis();
        Random ran = new Random();
        String line = System.getProperty("line.separator");
        File file = new File("random.csv");
        BufferedWriter bw = new BufferedWriter(new FileWriter(file));
        for(int i=1; i<=50000;i++) {            
            int num = ran.nextInt(99999) + 1;
            bw.write("\"");
            bw.write(String.format("%05d",num));
            bw.write("\"");
            if(i%5!=0) {
                bw.write(",");
            }else{
                bw.write(line);
            }
        }
        bw.close();
        long time = System.currentTimeMillis() - t0;
        System.out.printf("耗时：%d(ms)%n", time);
    }
}

------解决方案--------------------
呵呵，好了，第一个也完成了。

Java code
import java.io.BufferedReader;
import java.io.BufferedWriter;
import java.io.File;
import java.io.FileReader;
import java.io.FileWriter;
import java.io.IOException;
import java.util.ArrayList;
import java.util.Collections;
import java.util.Comparator;
import java.util.List;

public class CSVSort {

    public static void main(String[] args) {
        long t0 = System.currentTimeMillis();
        if (args.length != 3) {
            System.out.println("错误[1]：参数不正确！");
            System.out.println("使用方法: CSVSort <源文件名> <新文件名> <排序列号>");
            System.exit(1);
        }
        File file1 = new File(args[0]);
        if (!file1.exists()) {
            System.out.println("错误[2]: " + args[0] + " 文件没有找到！");
            System.exit(2);
        }
        File file2 = new File(args[1]);
        if (file2.exists()) {
            System.out.println("错误[3]: " + args[1] + " 文件已经存在！");
            System.exit(3);
        }
        List<String> list = readFile(file1);
        int tmp = list.get(0).split(",").length; // 计算总共的列数
        int col = Integer.parseInt(args[2]);
        if (col < 1 || col > tmp) {
            list.clear();
            System.out.println("错误[4]: 列号不正确！");
            System.exit(4);
        }
        sort(list, col);
        writeFile(file2, list);
        long time = System.currentTimeMillis() - t0;
        System.out.printf("耗时：%d(ms)%n", time);
    }

    public static List<String> readFile(File file) {
        BufferedReader br = null;
        List<String> list = new ArrayList<String>();
        try {
            br = new BufferedReader(new FileReader(file));
            String str = "";
            while ((str = br.readLine()) != null) {
                str = str.trim();
                if (str.length() > 0) {
                    list.add(str);
                }
            }
            br.close();
        } catch (IOException e) {
            e.printStackTrace();
        }
        return list;
    }

    public static void writeFile(File file, List<String> list) {
        BufferedWriter bw = null;
        try {
            String line = System.getProperty("line.separator");
            bw = new BufferedWriter(new FileWriter(file));
            for (String str : list) {
                bw.write(str);
                bw.write(line);
            }
            bw.close();
        } catch (IOException e) {
            e.printStackTrace();
        }
    }

    public static void sort(List<String> list, final int column) {
        Collections.sort(list, new Comparator<String>() {
            public int compare(String str1, String str2) {
                String[] str1s = str1.split(",");
                String[] str2s = str2.split(",");
                return str1s[column - 1].compareTo(str2s[column - 1]);
            }
        });
    }
}