code: public V setValueAt(int index, V value) {
          index = (index << 1) + 1;
          V old = (V)mArray[index];
          mArray[index] = value;
          return old;
      }
docs: Set the value at a given index in the array.
  @param index The desired index, must be between 0 and {@link #size()}-1.
  @param value The new value to store at this index.
  @return Returns the previous value at the given index.