All the examples I’ve seen so far for dealing with programmatically handling things from a view have involved an activity and the layout associated with it. But when I am working with Android Studio, whenever I create a new activity things are a little different and I get two layouts and things are happening in a fragment rather than the first layout. I don’t totally get the whole thing yet, I’m working on wrapping my mind around it. But today I did figure out something that was really giving me fits and I want to document it for later.
I wanted to start a new activity and in the view for that activity display a chart using the Android GraphView. Jonas provides nice documentation with example code on how to do this. But the fragment thing was really messing me up. I couldn’t figure out where to put the code and how to get it to work. The example I was interested in looks like this:
// init example series data GraphViewSeries exampleSeries = new GraphViewSeries(new GraphViewData[] { new GraphViewData(1, 2.0d) , new GraphViewData(2, 1.5d) , new GraphViewData(3, 2.5d) , new GraphViewData(4, 1.0d) }); GraphView graphView = new LineGraphView( this // context , "GraphViewDemo" // heading ); graphView.addSeries(exampleSeries); // data LinearLayout layout = (LinearLayout) findViewById(R.id.graph1); layout.addView(graphView);
But I would put it in different places and crash the app or get compiler errors before I even started. I did a lot of searching and reading before I got it to work and I guess I don’t need to rehash all that. It was the accepted answer on this stackoverflow question that finally put the last piece in place for me though.
When I create a new activity the class for it has a class inside that creates the fragment:
public static class PlaceholderFragment extends Fragment { public PlaceholderFragment() { } @Override public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) { View rootView = inflater.inflate(R.layout.fragment_main, container, false); return rootView; } }
This made sense as the place to do my work but I couldn’t figure out how. I had trouble trying to reference the view. But it was right in front of me the whole time. Here is what finally worked.
public static class PlaceholderFragment extends Fragment { public PlaceholderFragment() { } @Override public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) { View rootView = inflater.inflate(R.layout.fragment_show_graph, container, false); //I cannot believe I finally figured this out. GraphViewSeries avSeries = new GraphViewSeries(new GraphView.GraphViewData[] { new GraphView.GraphViewData(1, 223) , new GraphView.GraphViewData(2, 221) , new GraphView.GraphViewData(3, 220) , new GraphView.GraphViewData(4, 221) }); GraphView monthAverage = new LineGraphView(this.getActivity(), "Jan Data"); monthAverage.addSeries(avSeries); LinearLayout layout = (LinearLayout) rootView.findViewById(R.id.graphM); layout.addView(monthAverage); //this is the end of my part return rootView; } }
Oh – here’s the xml for the layout. I don’t think it matters a whole lot – but this is where the graphM id is located.
xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="fill_parent"
android:layout_height="match_parent"
android:paddingLeft="@dimen/activity_horizontal_margin"
android:paddingRight="@dimen/activity_horizontal_margin"
android:paddingTop="@dimen/activity_vertical_margin"
android:paddingBottom="@dimen/activity_vertical_margin"
android:orientation="vertical"
android:id="@+id/graphM"
tools:context="org.pyrrhic.eatwatch.showGraph$PlaceholderFragment">
>I was so happy when I ran this and I saw my graph pop up rather than the error message from the app crashing. It was a banner moment in my day.