Question

Good morning folks,

I’m working on an Android app and I’ve run into a bit of a problem. I have created a new class that extends View. I have overridden the appropriate methods (the Constructor, onDraw, onMeasure) and am instantiating the View through the applications layout XML (which is called main.xml).

Within the source code of my app I have the following code:

public class CustomViewTest extends Activity {
    /** Called when the activity is first created. */
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);

/* I *think* I need to setContentView before I actually can use any of the widgets on the form. */
        setContentView(R.layout.main);       
        Button b = (Button)findViewById(R.id.button);

        b.setOnClickListener(new OnClickListener() {

   @Override
   public void onClick(View v) {
    // TODO Auto-generated method stub
// my new widget
newWidget s = (newWidget)findViewById(R.id.testWidget);
s.setRequestedViewSize(300);
   }

        });


    }
}

the problem here, is that s.setRequestedViewSize(300) throws a NullPointerException. Has anyone run into this before or can lend me some advice?

[EDIT]
The main.XML looks like this:

It returning null, but the XML looks like this:

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:orientation="vertical"
    android:layout_width="fill_parent"
    android:layout_height="fill_parent"
    >
    <com.testing.CustomViewTest02.newWidget
        android:id="@+id/testWidget"
        android:layout_width="fill_parent"
        android:layout_height="fill_parent" />
    <Button android:id="@+id/button"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            ></Button>
</LinearLayout>

Thanks you!
Sam

Answer 1

The problem was in my widget, I had the correct constructor (Context context AttributeSet attr); HOWEVER – super(context) was being called – not super(context, attr). Once I fixed that, life was better.

Thanks for the info everyone!