Creating default values for custom attributes using styles and themes

Question

I have several custom `View`s in which I have created custom styleable attributes that are declared in xml layout and read in during the view's constructor. My question is, if I do not give explicit values to all of the custom attributes when defining my layout in xml, how can I use styles and themes to have a default value that will be passed to my `View`'s constructor? For example: attrs.xml: ``` ``` layout.xml (`android:` tags eliminated for simplicity): ``` <-- Custom attribute defined, get 0.2 passed to constructor --> <-- Custom attribute not defined, get a default (say 0.4) passed to constructor -->

Accepted Answer

After doing more research, I realized that default values can be set in the constructor for the `View` itself.

```
public class MyCustomView extends View {

private float mCustomAttribute;

public MyCustomView(Context context, AttributeSet attrs) {
        super(context, attrs);

TypedArray array = context.obtainStyledAttributes(attrs,
            R.styleable.MyCustomView);
        mCustomAttribute = array.getFloat(R.styleable.MyCustomView_customAttribute,
            0.4f);

array.recycle();
    }
}
```

The default value could also be loaded from an xml resource file, which could be varied based on screen size, screen orientation, SDK version, etc.

Creating default values for custom attributes using styles and themes

Solution

Problem