PAA - Helper - Bubble & Merge

import java.io.*;

public class Helper {

    static int tam[] = { 10240, 102400, 512000, 1048576 };

    public static int getTamanho(int n){
        return tam[n-1];
    }

    public static String criarArquivo(int n) throws IOException {
        int imp = 0, i;
        String dir = "";

        dir = "C:/temp/" + tam[n - 1] + ".txt";
        FileWriter arq = new FileWriter(dir);
        PrintWriter gravarArq = new PrintWriter(arq);

        for (i = 0; i < tam[n - 1]; i++) {
            imp = (int) (Math.random() * 10);
            gravarArq.print(imp);
        }
        arq.close();

        return dir;
    }

    public static char[] lerArquivo(String dir) throws IOException {
        char[] v = {};

        try{
            BufferedReader buf = new BufferedReader(new FileReader(dir));
            String line = "", l;
            while ((l = buf.readLine()) != null) {
                line += l;
            }
            v = line.toCharArray();
        }catch(Exception erro){
            System.out.println(erro.getMessage() + "\n");
            System.exit(0);
        }

        return v;
    }

}