simplest approach:
Use a custom object "FileWithLock" instead of "File". You can simply set a lock on that one and react.
import java.io.File;
public class FileWithLock extends File
{
private boolean locked = false;
public FileWithLock(String pathName){
super(pathName);
}
public void setLocked(boolean locked){
this.locked = locked;
}
public boolean bisLocked(){
return locked;
}
}