Class RandomAccessFile

classpath/java/io/RandomAccessFile.java:17–202

import java.nio.channels.FileChannel;

public class RandomAccessFile {
  private long peer;
  private File file;
  private long position = 0;
  private long length;
  private boolean allowWrite;

  public RandomAccessFile(String name, String mode)
    throws FileNotFoundException
  {
    this(new File(name), mode);
  }

  public RandomAccessFile(File file, String mode)
    throws FileNotFoundException
  {
    if (file == null) throw new NullPointerException();
    if (mode.equals("rw")) allowWrite = true;
    else if (! mode.equals("r")) throw new IllegalArgumentException();
    this.file = file;
    open();
  }

  private void open() throws FileNotFoundException {
    long[] result = new long[2];
    open(file.getPath(), allowWrite, result);
    peer = result[0];
    length = result[1];
  }

  private static native void open(String name, boolean allowWrite, long[] result)
    throws FileNotFoundException;

  private void refresh() throws IOException {
    if (file.length() != length) {
      close();
      open();
    }
  }

  public long length() throws IOException {
    refresh();
    return length;
  }

  public long getFilePointer() throws IOException {
    return position;
  }

  public void seek(long position) throws IOException {
    if (position < 0 || (!allowWrite && position > length())) throw new IOException();

    this.position = position;
  }

  public int skipBytes(int count) throws IOException {
    if (position + count > length()) throw new IOException();
    this.position = position + count;