import java.nio.*;import java.nio.channels.*;import java.io.*;public class test{    public interface BinaryPersistent {	   	   abstract public ByteBuffer toBytes();	   	   abstract void read(ByteBuffer data);	       }    private static  class A implements BinaryPersistent    {	   int i = 10;	   public A()	   {		  System.out.println("Hello from A");	   }  	   public ByteBuffer toBytes() {		  //Fill some info		  ByteBuffer buf = ByteBuffer.allocate(1024);		  buf.putInt(50); // use setters to write data		  buf.putInt(50); // use setters to write data		  buf.putInt(50); // use setters to write data		  buf.putInt(50); // use setters to write data		  buf.putInt(50); // use setters to write data		  buf.putInt(50); // use setters to write data		  buf.putInt(50); // use setters to write data		  buf.rewind();		  // order buffer		  System.out.println("Converted A to Bytes");		  return buf;	   }	   public void read(ByteBuffer buffer) {		  // get data using getXXX() methods on the buffer;	   }    }    private static final class B extends A    {	   int j = 20;	   public B()	   {		  System.out.println("Hello from B");	   }    }    public static void main(String[] Args)    {	   B b1 = new B();	   File file = new File("filename");	   	   ByteBuffer bbuf = b1.toBytes();	   boolean append = false;    	   try		  {			 // Create a writable file channel			 FileChannel wChannel = new FileOutputStream(file, append).getChannel();			 			 // Write the ByteBuffer contents; the bytes between the ByteBuffer's			 // position and the limit is written to the file			 wChannel.write(bbuf);			 			 // Close the file			 wChannel.close();		  } 	   catch (IOException e) 		  {		  } 	   try 		  {			 // Obtain a channel			 ReadableByteChannel channel = new FileInputStream("filename").getChannel();    			 // Create a direct ByteBuffer; see also e158 Creating a ByteBuffer			 ByteBuffer buf = ByteBuffer.allocateDirect(10);    			 int numRead = 0;			 while (numRead >= 0) {				// read() places read bytes at the buffer's position so the				// position should always be properly set before calling read()				// This method sets the position to 0				buf.rewind();    				// Read bytes from the channel				numRead = channel.read(buf);    				// The read() method also moves the position so in order to				// read the new bytes, the buffer's position must be set back to 0				buf.rewind();    				// Read bytes from ByteBuffer; see also				// e159 Getting Bytes from a ByteBuffer				for (int i=0; i < numRead / 4; i++) {				    System.out.println(buf.getInt());				    //byte b = buf.get();				 }			 }			 		  }	   catch (Exception e)		  {		  }    }}