MinOccurance2.java

import java.io.*;

public class MinOccurance2 {
  
  public static void main (String[] args) throws IOException {
    int[] occur = new int[256]; 
    int current = 0;
    
    RandomAccessFile file = new RandomAccessFile("test.txt", "r");
    long length = file.length();
    for ( int i = 0; i < length; i++) {
 
    current = file.read();

    int highNibble = Current >>> 4 ;
    int lowNibble = Current & 0x0f;

    occur[highNibble]++;
    occur[lowNibble]++;
    }
    
    for ( int k = 0; k < 4; k++) {
      System.out.println(k + " " + occur[k]);
    }

  }
  
}