huanghaibin-dev/CalendarView · warning

e.printStackTrace()

Error message

e.printStackTrace()

What it means

YearViewAdapter.onCreateDefaultViewHolder reflectively instantiates the configured custom year view. On failure it prints the stack trace and falls back to DefaultYearView, so the year picker renders with default styling instead of the user's custom year view.

Solutions

1. Declare a public constructor taking Context.
2. Make the class public, top-level or static nested, extending BaseYearView.
3. Inspect logcat for the printed reflection exception.
4. Add -keep class com.example.CustomYearView { public <init>(android.content.Context); } to proguard-rules.pro.
5. Confirm app:calendar_year_view_class matches the exact fully-qualified name.

Example fix

// before
app:calendar_year_view_class="com.app.YearPage" // class has no (Context) ctor
// after
// public class YearPage extends BaseYearView { public YearPage(Context c){super(c);} }
app:calendar_year_view_class="com.app.YearPage"

Class<?> cls = Class.forName("com.example.CustomYearView");
cls.getConstructor(Context.class);

static boolean instantiableYearView(Class<?> cls) {
    try {
        return BaseYearView.class.isAssignableFrom(cls)
            && cls.getConstructor(Context.class) != null;
    } catch (NoSuchMethodException e) { return false; }
}

// Library falls back to DefaultYearView; preflight:
try {
    CustomYearView.class.getConstructor(Context.class).newInstance(context);
} catch (Throwable t) {
    Log.w("Calendar", "CustomYearView failed; DefaultYearView will be used", t);
}

When it happens

Trigger: Class from app:calendar_year_view_class has no public (Context) constructor, is a non-static inner class, throws during construction, or is stripped/renamed by code shrinking.

Common situations: Custom YearView written as an Activity inner class; R8 minified release builds without keep rules; constructor expecting an Activity context; wrong XML class path after refactoring.

Related errors

• e.printStackTrace()
• e.printStackTrace()
• e.printStackTrace()
• e.printStackTrace()

AI-assisted analysis of huanghaibin-dev/CalendarView@f5479ea3ba (2026-09-11). Data as JSON: /api/errors/c50705a1fc5509ae. Report an issue: GitHub.

Appendix: source

Thrown at calendarview/src/main/java/com/haibin/calendarview/YearViewAdapter.java:55

    }


    final void setYearViewSize(int width, int height) {
        this.mItemWidth = width;
        this.mItemHeight = height;
    }

    @Override
    RecyclerView.ViewHolder onCreateDefaultViewHolder(ViewGroup parent, int type) {
        YearView yearView;
        if (TextUtils.isEmpty(mDelegate.getYearViewClassPath())) {
            yearView = new DefaultYearView(mContext);
        } else {
            try {
                Constructor constructor = mDelegate.getYearViewClass().getConstructor(Context.class);
                yearView = (YearView) constructor.newInstance(mContext);
            } catch (Exception e) {
                e.printStackTrace();
                yearView = new DefaultYearView(mContext);
            }
        }
        RecyclerView.LayoutParams params = new RecyclerView.LayoutParams(RecyclerView.LayoutParams.MATCH_PARENT,
                RecyclerView.LayoutParams.MATCH_PARENT);
        yearView.setLayoutParams(params);
        return new YearViewHolder(yearView, mDelegate);
    }

    @Override
    void onBindViewHolder(RecyclerView.ViewHolder holder, Month item, int position) {
        YearViewHolder h = (YearViewHolder) holder;
        YearView view = h.mYearView;
        view.init(item.getYear(), item.getMonth());
        view.measureSize(mItemWidth, mItemHeight);
    }

    private static class YearViewHolder extends RecyclerView.ViewHolder {

View on GitHub (pinned to f5479ea3ba)