code: public static MutableSymbolTable readStringMap(ObjectInput in)
        throws IOException, ClassNotFoundException {
  
      int mapSize = in.readInt();
      MutableSymbolTable syms = new MutableSymbolTable();
      for (int i = 0; i < mapSize; i++) {
        String sym = in.readUTF();
        int index = in.readInt();
        syms.put(sym, index);
      }
      return syms;
    }
docs: Deserializes a symbol map from an java.io.ObjectInput
  
  @param in the java.io.ObjectInput. It should be already be initialized by the caller.
  @return the deserialized symbol map