Extending MaterialButton: Should it be done? SavedState has package visibility

Issue

I have extended the MaterialButton to display a consistent loading state on the button when clicked however I ran into a minor issue when implementing SavedState restoration.

The progress button variant of this I have written, disables the view, displays an animated loading spinner, optionally displays loading text and restores then restores the previously displayed text/state when the view is enabled.

MaterialButton.SavedState is package-private so cannot be extended externally. This does not create a problem with my implementation as I don't use the 'checked' field it extends but it does raise these questions:

TLDR

• Is it wrong to extend this MaterialButton?
• If not would it be appropriate to submit a PR to the public repo to make SavedState public?

material-components-android:1.2.0

Solution

Is it wrong to extend this MaterialButton?

The MaterialButton is not a final class then you can extend it, and for example the ExtendedFloatingActionButton extends it.

If not would it be appropriate to submit a PR to the public repo to make SavedState public?

You don't need to make MaterialButton.SavedState public. You can do something like:

public class MyButton extends MaterialButton
{
    private String text;

    //....


    static class SavedState extends AbsSavedState {
        @Nullable CharSequence myText;

        SavedState(Parcelable superState) {
            super(superState);
        }

        SavedState(@NonNull Parcel source, ClassLoader loader) {
            super(source, loader);
            myText = TextUtils.CHAR_SEQUENCE_CREATOR.createFromParcel(source);
        }

        @Override
        public void writeToParcel(@NonNull Parcel dest, int flags) {
            super.writeToParcel(dest, flags);
            TextUtils.writeToParcel(myText, dest, flags);
        }

        @NonNull
        @Override
        public String toString() {
            return "MyButton.SavedState{"
                    + " text="
                    + myText
                    + "}";
        }

        public static final Creator<SavedState> CREATOR =
                new ClassLoaderCreator<SavedState>() {
                    @NonNull
                    @Override
                    public SavedState createFromParcel(@NonNull Parcel in, ClassLoader loader) {
                        return new SavedState(in, loader);
                    }

                    @Nullable
                    @Override
                    public SavedState createFromParcel(@NonNull Parcel in) {
                        return new SavedState(in, null);
                    }

                    @NonNull
                    @Override
                    public SavedState[] newArray(int size) {
                        return new SavedState[size];
                    }
                };
    }

    @Nullable
    @Override
    public Parcelable onSaveInstanceState() {
        Parcelable superState = super.onSaveInstanceState();
        SavedState ss = new SavedState(superState);
        ss.myText = text;
        return ss;
    }

    @Override
    public void onRestoreInstanceState(@Nullable Parcelable state) {
        if (!(state instanceof SavedState)) {
            super.onRestoreInstanceState(state);
            return;
        }
        SavedState ss = (SavedState) state;
        super.onRestoreInstanceState(ss.getSuperState());
        text = ss.myText.toString();
    }
}

In this way the MyButton.SavedState will contain also the MaterialButton.SaveState without extending it.

Answered By - Gabriele Mariotti