How do I use filechannel to append the contents of one file to the end of another?

The file a.txt looks like:

ABC

The file d.txt looks like: @ h_ 404_ 5@

DEF

I'm trying to take "def" and attach it to "ABC", so a.txt looks like @ H_ 404_ 5@

ABC
DEF

The method I tried always completely overwrites the first entry, so I always end up with: @ h_ 404_ 5@

DEF

Here are two methods I have tried: @ h_ 404_ 5@

FileChannel src = new FileInputStream(dFilePath).getChannel(); 
FileChannel dest = new FileOutputStream(aFilePath).getChannel();

src.transferTo(dest.size(),src.size(),dest);

... I tried @ H_ 404_ 5@

FileChannel src = new FileInputStream(dFilePath).getChannel(); 
FileChannel dest = new FileOutputStream(aFilePath).getChannel();

dest.transferFrom(src,dest.size(),src.size());

API unclear transferto and transferfrom param Description: @ h_ 404_ 5@

http://docs.oracle.com/javase/7/docs/api/java/nio/channels/FileChannel.html#transferTo (long,long,java.nio.channels.WritableByteChannel)@H_ 404_ 5@

Thank you for any ideas@ H_ 404_ 5@

Solution

Move the position of the target channel to the end:

FileChannel src = new FileInputStream(dFilePath).getChannel(); 
FileChannel dest = new FileOutputStream(aFilePath).getChannel();
dest.position( dest.size() );
src.transferTo(0,dest);