Optimal Page Replacement in Java

// importing packages to use classes in the page replacement program
import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
public class OptimalReplacement
{

// creation of the main class to implement Optimal page replacement algorithm
  public static void main (pagestring[]args) throws IOException
  {
    Countbuffer bfr = new Countbuffer (new InputStreamReader (System.in));
    int frames, pointer = 0, hit = 0, fault = 0, strng_size;
    boolean isFull = false;
    int buffer[];
    int ref[];
    int mem_layout[][];

//Entering the number of frames
      System.out.println (" Enter the total number of Frames: ");
      frames = Integer.parseInt (br.readLine ());

//Entering the string size of the reference
      System.out.println (" Enter the reference string size:");
      strng_size = Integer.parseInt (br.readLine ());

      ref = new int[ref_len];
      mem_layout = new int[strng_size][frames];
      buffer = new int[frames];
    for (int j = 0; j < frames; j++)
        buffer[j] = -1;

//code to enter the reference string to carry out optimal page replacement
      System.out.println (" Enter the reference string: ");
    for (int i = 0; i < strng_size; i++)
      {
	ref[i] = Integer.parseInt (br.readLine ());
      }

    System.out.println ();
    for (int i = 0; i < strng_size; i++)
      {
	int search = -1;
	for (int j = 0; j < frames; j++)
	  {
	    if (buffer[j] == ref[i])
	      {
		search = j;
		hit++;
		break;
	      }
	  }
// code to update the stack checking its capacity
	if (search == -1)
	  {
	    if (isFull)
	      {
		int index[] = new int[frames];
		boolean index_flag[] = new boolean[frames];
		for (int j = i + 1; j < ref_len; j++)
		  {
		    for (int k = 0; k < frames; k++)
		      {
			if ((ref[j] == buffer[k]) && (index_flag[k] == false))
			  {
			    index[k] = j;
			    index_flag[k] = true;
			    break;
			  }
		      }
		  }

//updating pointer to the correct memory location after checking capacity
		buffer[pointer] = ref[i];
		fault++;
		if (!isFull)
		  {
		    pointer++;
		    if (pointer == frames)
		      {
			pointer = 0;
			isFull = true;
		      }
		  }
	      }
	    for (int j = 0; j < frames; j++)
	      mem_layout[i][j] = buffer[j];
	  }

// code to display the number strings
	for (int i = 0; i < frames; i++)
	  {
	    for (int j = 0; j < ref_len; j++)
	      System.out.printf ("%3d ", mem_layout[j][i]);
	    System.out.println ();
	  }

	System.out.println ("Hits: " + hit);
	System.out.println ("Hit Ratio: " + (float) ((float) hit / str_len));
	System.out.println ("Faults: " + fault);
      }

  }