具有可滚动水平行的ListView

Question

Working on a ListView with a custom list view adepter inherited from BaseAdapter . I'm trying to implement a table style in which each row is horizontally scrollable. Therefore, I'm using HorizontalScrollView and LinearLayout to structure each row. In each row, there are multiple TextView with hardcoded texts in each. Everything is happening in the code and there's no xml and layout file. The issue that I'm having is I don't see any of TextView items that I add to my LinearLayout . Those TextView are added as a child view to LinearLayout and inside onLayout method on set up their layout as:

int dx = 0, viewWidth = 180;
for (int i = 0; i < m_Views.length; i++) {

TextView view = m_Views[i];

int textViewWidth = viewWidth;
if (i == 0) {
    textViewWidth *= 2;
}

view.layout(dx, 0, dx + textViewWidth, contentHeight);

dx += textViewWidth;
}
m_HorizontalScrollView.layout(0, 0, contentWidth, contentHeight);
m_LinearLayout.layout(0, 0, dx, contentHeight);

That code, doesn't render TextView elements. In addition, if I try to add the following line before setting the view's layout:

view.measure(MeasureSpec.UNSPECIFIED, MeasureSpec.UNSPECIFIED);

The app crashes with the following error in LinearLayout.java class, java.lang.NullPointerException: Attempt to read from null array .

I'm curious to know:

1. Why the layout of text views don't change with calling layout method?
2. Why does the app crashes if I call measure method?

PS: Using RecyclerView or any other approaches that requires in changing the adepter and list view is out of scope since that requires changing in the framework and base classes.

Answer 1

You should not be calling layout or measure direction on a view. Rather, you should set the LayoutParams of the view using View.setLayoutParams() . Since you are using a LinearLayout, you would use LinearLayout.LayoutParams as your concrete implementation. Remove all direct calls to layout and measure and let the Android layout system handle this.