@Override public void readExternal(ObjectInput in) throws IOException, ClassNotFoundException {
  this.parent=in.readInt();
  this.componentType=in.readUTF();
  this.id=in.readUTF();
  if (id.length() == 0) {
    id=null;
  }
}

@ Override public void readExternal ( ObjectInput in ) throws IOException , ClassNotFoundException { this . parent = in . readInt ( ) ; this . componentType = in . readUTF ( ) ; this . id = in . readUTF ( ) ; if ( id . length ( ) == 0 ) { id = null ; } }
read the tree node in .
