String readFromFile(String strFile)
    {
       File file = new File(strFile);
       URI uri = file.toURI();
       byte[] bytes = null;
       try{
          bytes = java.nio.file.Files.readAllBytes(java.nio.file.Paths.get(uri));
       }catch(IOException e) { e.printStackTrace(); return "ERROR loading file "+strFile; }
    
       return new String(bytes);
    }

str.append(line + "\n");
line = br.readLine();

ArrayList<String> fileContents = new ArrayList<>(); // Please excuse the Java 7 code here, I'm lazy
BufferedReader br = new BufferedReader(new FileReader(file));
String line = br.readLine();
while(line != null)
{
   fileContents.add(line);
   line = br.readLine();
}

public static final String readFile(String file) throws IOException {
   BufferedInputStream in = new BufferedInputStream(new FileInputStream(file));
   ByteBuffer buffer = new ByteBuffer();
   byte[] buf = new byte[1024];
   int len;
   while ((len = in.read(buf)) != -1) {
      buffer.put(buf, len);
   }
   in.close();
   return new String(buffer.buffer, 0, buffer.write);
}

class ByteBuffer {

   public byte[] buffer = new byte[256];

   public int write;

   public void put(byte[] buf, int len) {
      ensure(len);
      System.arraycopy(buf, 0, buffer, write, len);
      write += len;
   }

   private void ensure(int amt) {
      int req = write + amt;
      if (buffer.length <= req) {
         byte[] temp = new byte[req * 2];
         System.arraycopy(buffer, 0, temp, 0, write);
         buffer = temp;
      }
   }

}

public final static String readFile(String fileName) throws IOException {
   File f = new File(fileName);
   FileInputStream fstream = new FileInputStream(f);
   byte[] bytes = new byte[(int) f.length()];
   fstream.read(bytes);
   fstream.close();
   return new String(bytes);
}

long before = System.nanoTime();
       
       for (int i=0;i<100;i++)
       {
          Util.readFromFile(path);
       }
       System.out.println("1: "+((System.nanoTime()-before)/1000L)+"us");
       
       
       before = System.nanoTime();
       for (int i=0;i<100;i++)
       {
          Util.readFileWithChannel(path);
       }
       System.out.println("2: "+((System.nanoTime()-before)/1000L)+"us");
       
       
       before = System.nanoTime();
       for (int i=0;i<100;i++)
       {
          Util.readFromFileJava7(path);
       }
       System.out.println("3: "+((System.nanoTime()-before)/1000L)+"us");

1: 305061us
2: 1579026us
3: 1476928us

       int iterations = 20;
       long before = System.nanoTime();
       scrambleFile(path);

       for (int i=0;i<iterations;i++)
       {
          Util.readFromFileJava7(path);
          scrambleFile(path);
       }
       System.out.println("1: "+((System.nanoTime()-before)/1000L/1000L)+"ms");
       
       before = System.nanoTime();
       for (int i=0;i<iterations;i++)
       {
          Util.readFileWithChannel(path);
          scrambleFile(path);
       }
       System.out.println("2: "+((System.nanoTime()-before)/1000L/1000L)+"ms");
       
       before = System.nanoTime();
       for (int i=0;i<iterations;i++)
       {
          Util.readFromFile(path);
          scrambleFile(path);
       }
       System.out.println("3: "+((System.nanoTime()-before)/1000L/1000L)+"ms\n\n");
       
       long r = 0L;
       for (int i=0;i<iterations;i++)
       {
          before = System.nanoTime();
          scrambleFile(path);
          r += ((System.nanoTime()-before)/1000L/1000L);
       }
       System.out.println("Scramble test average: "+(r/(float)iterations)+"ms");
       scrambleFile(path);

1: 668ms
2: 614ms
3: 655ms


Scramble test average: 29.45ms