Using Butterknife to inject an array of views

Question

Currently I have this array of views:

ImageView activityImageViews[] = {
    (ImageView) rootView.findViewById(R.id.img_activity_1),
    (ImageView) rootView.findViewById(R.id.img_activity_2),
    (ImageView) rootView.findViewById(R.id.img_activity_3),
    (ImageView) rootView.findViewById(R.id.img_activity_4)
};

Is there a way I could use Butterknife to inject all those views? I need to keep them in an array (or in a way so I can iterate over them).

Turtledove

Just recently stumbled upon Butterknife so do not know if it supports that directly but why not just inject them individually and collect them in an array or a list inside onCreate? – Cristoforo

Answer 1

Currently it is possible to inject several views as array. From ButterKnife documentation (see VIEW LISTS section)

@InjectViews({ R.id.first_name, R.id.middle_name, R.id.last_name })
List<EditText> nameViews;

Same thing for multiple click listeners:

@OnClick({ R.id.door1, R.id.door2, R.id.door3 })
public void pickDoor(DoorView door) {
  if (door.hasPrizeBehind()) {
    Toast.makeText(this, "You win!", LENGTH_SHORT).show();
  } else {
    Toast.makeText(this, "Try again", LENGTH_SHORT).show();
  }
}

UPDATE 2017-09-19: Since Butterknife version Version 7.0.0 (2015-06-27) @Bind replaced @InjectView and @InjectViews. But since version Version 8.0.0 (2016-04-25) @Bind was replaced with @BindView and @BindViews for one view and multiple views, respectively. So for now the correct syntax is:

@BindView(R.id.button1) Button button1;
@BindView(R.id.button2) Button button2;

@BindViews({ R.id.first_name, R.id.middle_name, R.id.last_name })
List<EditText> nameViews;

Soche

Cool! Even though I'm not working on that project anymore, it's good to know for future reference so thanks :) – Turtledove

Answer 2

I suppose that the elements added to the Array are dynamically, otherwise you can simply declare them in your header one by one and afterwards add them to the array:

// in the header:
@InjectView(R.id.imageview1) ImageView imageView1;
@InjectView(R.id.imageview2) ImageView imageView2;
@InjectView(R.id.imageview3) ImageView imageView3;

// inside your code:
ImageView activityImageViews[] = {
    imageView1, imageView2, imageView3
};

But however, if the elements are dynamic (in amount of elements/id of elements etc.) the only thing you can do is to use ButterKnife.findById which will spare the ImageView cast - you can't inject them via annotation because Butterknife does not know what to generate/inject on compile time (the information is first available on runtime).

ImageView activityImageViews[] = {
    ButterKnife.findById(view, R.id.img_activity_1),
    ButterKnife.findById(view, R.id.img_activity_2),
    ButterKnife.findById(view, R.id.img_activity_3),
    ButterKnife.findById(view, R.id.img_activity_4)
};

Hendon

The second snippet gives Incompatible types. Required: android.widget.ImageView, Found: android.view.View. I'll use your first approach, thank you! – Turtledove

Hmm, that's strange. I use ButterKnife 4.0.1 and also the second approach works fine for me. The documentation says [...]It uses generics to infer the return type and automatically performs the cast. – Hendon