material-components/material-components-android · error · RuntimeException

EditText needs to be an AutoCompleteTextView if an Exposed D

Error message

EditText needs to be an AutoCompleteTextView if an Exposed Dropdown Menu is being used.

What it means

DropdownMenuEndIconDelegate powers the END_ICON_DROPDOWN_MENU end icon in a TextInputLayout. Its machinery (threshold, popup sync) only works on an AutoCompleteTextView, so when the layout's EditText is some other EditText subclass it throws a RuntimeException via castAutoCompleteTextViewOrThrow.

Source

Thrown at lib/java/com/google/android/material/textfield/DropdownMenuEndIconDelegate.java:291

      }
      return false;
    });
    autoCompleteTextView.setOnDismissListener(() -> {
      updateDropdownPopupDirty();
      setEndIconChecked(false);
    });
    autoCompleteTextView.setThreshold(0);
  }

  private boolean isDropdownPopupActive() {
    long activeFor = SystemClock.uptimeMillis() - dropdownPopupActivatedAt;
    return activeFor < 0 || activeFor > 300;
  }

  @NonNull
  private static AutoCompleteTextView castAutoCompleteTextViewOrThrow(EditText editText) {
    if (!(editText instanceof AutoCompleteTextView)) {
      throw new RuntimeException(
          "EditText needs to be an AutoCompleteTextView if an Exposed Dropdown Menu is being"
              + " used.");
    }

    return (AutoCompleteTextView) editText;
  }

  private void updateDropdownPopupDirty() {
    dropdownPopupDirty = true;
    dropdownPopupActivatedAt = SystemClock.uptimeMillis();
  }

  private void setEndIconChecked(boolean checked) {
    if (isEndIconChecked != checked) {
      isEndIconChecked = checked;
      fadeInAnim.cancel();
      fadeOutAnim.start();
    }

View on GitHub (pinned to ac7e18efee)

Solutions

1. Use an AutoCompleteTextView as the TextInputLayout's child, e.g. <AutoCompleteTextView style="@style/Widget.Material3.AutoCompleteTextView.OutlinedExposedDropdownMenu"/> (or the M2 ExposedDropdownMenu equivalent).
2. Or use the ready-made style on the TextInputLayout: Widget.Material3.TextInputLayout.OutlinedBox.ExposedDropdownMenu.
3. If the field is not a dropdown, remove END_ICON_DROPDOWN_MENU and use another end icon mode.

Example fix

<!-- before -->
<com.google.android.material.textfield.TextInputLayout app:endIconMode="dropdown_menu">
  <com.google.android.material.textfield.TextInputEditText/>
</com.google.android.material.textfield.TextInputLayout>

<!-- after -->
<com.google.android.material.textfield.TextInputLayout
    style="@style/Widget.Material3.TextInputLayout.OutlinedBox.ExposedDropdownMenu">
  <AutoCompleteTextView
      style="@style/Widget.Material3.AutoCompleteTextView.OutlinedExposedDropdownMenu"/>
</com.google.android.material.textfield.TextInputLayout>

if (til.getEditText() instanceof android.widget.AutoCompleteTextView) {
  til.setEndIconMode(TextInputLayout.END_ICON_DROPDOWN_MENU);
} else {
  // not a dropdown field: pick another end icon mode or fix the layout XML
}

private boolean supportsDropdownEndIcon(@NonNull TextInputLayout til) {
  return til.getEditText() instanceof AutoCompleteTextView;
}

When it happens

Trigger: Setting app:endIconMode="dropdown_menu" (or setEndIconMode(END_ICON_DROPDOWN_MENU)) on a TextInputLayout whose TextInputEditText is a plain TextInputEditText or other non-AutoCompleteTextView; using the ExposedDropdownMenu style but keeping TextInputEditText as the inner edit field.

Common situations: Copy-pasting a filled/outlined TextInputLayout block and switching the style to ExposedDropdownMenu without swapping the inner view; mixing a custom EditText subclass with the dropdown end icon.

Related errors

• The current box background mode is not supported by the end
• Non color resource found: name={name}, typeId={typeId}
• endIconSize cannot be less than 0
• Invalid end icon mode:
• startIconSize cannot be less than 0

AI-assisted analysis of material-components/material-components-android@ac7e18efee (2026-08-14). Data as JSON: /api/errors/64446b1389f24175. Report an issue: GitHub.