If MergeView contains subgroups who have Views and MergeViews, then MergeView.readFrom() is probably incorrect because readFrom() explicitly creates a View, not a MergView :

public void readFrom(DataInputStream in) throws IOException, IllegalAccessException, InstantiationException {
super.readFrom(in);
short len=in.readShort();
if(len > 0) {
View v;
subgroups=new Vector();
for(int i=0; i < len; i++)

{ v=new View(); // <========= here v.readFrom(in); subgroups.add(v); }

}
}