we can annotate fields with @BindView
and a view ID for Butter Knife to find and automatically cast the corresponding view in our layout.
class ExampleActivity extends Activity {
@BindView(R.id.title) TextView title;
@BindView(R.id.subtitle) TextView subtitle;
@BindView(R.id.footer) TextView footer;
@Override public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.simple_activity);
ButterKnife.bind(this);
// TODO Use fields...
}
}
public class FancyFragment extends Fragment {
@BindView(R.id.button1) Button button1;
@BindView(R.id.button2) Button button2;
private Unbinder unbinder;
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
View view = inflater.inflate(R.layout.fancy_fragment, container, false);
unbinder = ButterKnife.bind(this, view);
// TODO Use fields...
return view;
}
// in fragments or non activity bindings we need to unbind the binding when view is about to be destroyed
@Override
public void onDestroy() {
super.onDestroy();
unbinder.unbind();
}
}
We can use ButterKnife.findById
to find views on a View, Activity, or Dialog. It uses generics to infer the return type and automatically performs the cast.
View view = LayoutInflater.from(context).inflate(R.layout.thing, null);
TextView firstName = ButterKnife.findById(view, R.id.first_name);
TextView lastName = ButterKnife.findById(view, R.id.last_name);
ImageView photo = ButterKnife.findById(view, R.id.photo);
static class ViewHolder {
@BindView(R.id.title) TextView name;
@BindView(R.id.job_title) TextView jobTitle;
public ViewHolder(View view) {
ButterKnife.bind(this, view);
}
}
Apart from being useful for binding views, one could also use ButterKnife to bind resources such as those defined within strings.xml
, drawables.xml
, colors.xml
, dimens.xml
, etc.
public class ExampleActivity extends Activity {
@BindString(R.string.title) String title; @BindDrawable(R.drawable.graphic) Drawable graphic; @BindColor(R.color.red) int red; // int or ColorStateList field @BindDimen(R.dimen.spacer) Float spacer; // int (for pixel size) or float (for exact value) field
@Override public void onCreate(Bundle savedInstanceState) {
// ...
ButterKnife.bind(this);
}
}