Working with RandomAccessFile : Files « File Input Output « Java

1. Java
2. File Input Output
3. Files

Working with RandomAccessFile

  
import java.io.IOException;
import java.io.RandomAccessFile;

public class Diff {
  public static void main(String args[]) {
    RandomAccessFile fh1 = null;
    RandomAccessFile fh2 = null;
    int bufsize; // size of smallest file
    long filesize1 = -1;
    long filesize2 = -1;
    byte buffer1[]; // the two file caches
    byte buffer2[];
    // check what you get as command-line arguments
    if (args.length == 0 || args[0].equals("?")) {
      System.err.println("USAGE: java Diff <file1> <file2> | ?");
      System.exit(0);
    }
    // open file ONE for reading
    try {
      fh1 = new RandomAccessFile(args[0], "r");
      filesize1 = fh1.length();
    } catch (IOException ioErr) {
      System.err.println("Could not find " + args[0]);
      System.err.println(ioErr);
      System.exit(100);
    }
    // open file TWO for reading
    try {
      fh2 = new RandomAccessFile(args[1], "r");
      filesize2 = fh2.length();
    } catch (IOException ioErr) {
      System.err.println("Could not find " + args[1]);
      System.err.println(ioErr);
      System.exit(100);
    }
    if (filesize1 != filesize2) {
      System.out.println("Files differ in size !");
      System.out.println("'" + args[0] + "' is " + filesize1 + " bytes");
      System.out.println("'" + args[1] + "' is " + filesize2 + " bytes");
    }
    // allocate two buffers large enough to hold entire files
    bufsize = (int) Math.min(filesize1, filesize2);
    buffer1 = new byte[bufsize];
    buffer2 = new byte[bufsize];
    try {
      fh1.readFully(buffer1, 0, bufsize);
      fh2.readFully(buffer2, 0, bufsize);

      for (int i = 0; i < bufsize; i++) {
        if (buffer1[i] != buffer2[i]) {
          System.out.println("Files differ at offset " + i);
          break;
        }
      }
    } catch (IOException ioErr) {
      System.err
          .println("ERROR: An exception occurred while processing the files");
      System.err.println(ioErr);
    } finally {
      try {
        fh1.close();
        fh2.close();
      } catch (IOException ignored) {
      }
    }
  }
}


           
         
    
  

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