how to set fixed size on GridView

FixedGridView.java

// working only when gridview is in ScrollView
private void setFixedHeightOnGridView() {

      int fixedHeight = 0;
      int columnCount = 2;
      int rows = 0;

      for (int i = 0; i < mNavigationView.getAdapter().getCount(); i = i + columnCount) {
          int highestItemInRow = 0;
          for (int j = i; j < i + columnCount; j++) {
              View item = mNavigationView.getAdapter().getView(i, null, mNavigationView);
              if (item instanceof ViewGroup) {
                  item.setLayoutParams(new LayoutParams(LayoutParams.MATCH_PARENT, LayoutParams.WRAP_CONTENT));
              }

              item.measure(0, 0);

              if (item.getMeasuredHeight() > highestItemInRow) {
                  highestItemInRow = item.getMeasuredHeight();
              }

          }
          fixedHeight += highestItemInRow;
          rows++;
    }

    // only if you want vertical spacing
    int verticalSpacing = getResources().getDimensionPixelOffset(R.dimen.nav_menu_vertical_spacing);
    fixedHeight += (rows) * verticalSpacing;
    ScrollView.LayoutParams layoutParams = (ScrollView.LayoutParams)
            mNavigationView.getLayoutParams();
    layoutParams.height = fixedHeight;
    mNavigationView.setLayoutParams(layoutParams);
}