Android Material CalendarView如何为不同日期分组设置对应装饰样式

• 你复用了同一个ArrayList实例存储不同分组的日期，创建黄色分组装饰器时，传入的集合已经包含了红色分组的2个日期，导致装饰范围错误
• 未对Drawable调用mutate()方法，Android默认共享同一份Drawable资源的常量状态，多个装饰器修改tint时会互相覆盖

1. MainActivity逻辑修改 #

不同分组使用独立的日期集合，代码如下：

// 红色分组：独立创建集合
ArrayList<CalendarDay> redDates = new ArrayList<>();
redDates.add(CalendarDay.from(2021, 8, 29)); // 注意：CalendarDay月份从0开始，8代表9月
redDates.add(CalendarDay.from(2021, 8, 30));
materialCalendarView.addDecorator(new mDayDecorator(Color.RED, redDates, MainActivity.this));

// 黄色分组：新建另一个集合，不要复用上面的集合
ArrayList<CalendarDay> yellowDates = new ArrayList<>();
yellowDates.add(CalendarDay.from(2021, 8, 1));
yellowDates.add(CalendarDay.from(2021, 8, 2));
yellowDates.add(CalendarDay.from(2021, 8, 3));
yellowDates.add(CalendarDay.from(2021, 8, 4));
yellowDates.add(CalendarDay.from(2021, 8, 5));
yellowDates.add(CalendarDay.from(2021, 8, 6));
materialCalendarView.addDecorator(new mDayDecorator(Color.YELLOW, yellowDates, MainActivity.this));

2. mDayDecorator修改 #

添加Drawable的mutate调用，避免状态共享：

public class mDayDecorator implements DayViewDecorator {

    private Drawable drawable;
    private int color;
    private HashSet<CalendarDay> dates = new HashSet<>();

    @RequiresApi(api = Build.VERSION_CODES.LOLLIPOP)
    public mDayDecorator(int color, Collection<CalendarDay> dates, Context context) {
        this.color = color;
        this.dates = new HashSet<>(dates);
        // 调用mutate() 避免多个装饰器共享Drawable状态
        drawable = context.getDrawable(R.drawable.more).mutate();
    }

    @Override
    public boolean shouldDecorate(CalendarDay day) {
        return dates.contains(day);
    }

    @RequiresApi(api = Build.VERSION_CODES.LOLLIPOP)
    @Override
    public void decorate(DayViewFacade view) {
        drawable.setTint(color);
        view.setSelectionDrawable(drawable);
    }
}

提示：如果同一个日期存在于多个分组的集合中，后添加的装饰器效果会覆盖先添加的，可根据业务需要调整装饰器的添加顺序。

内容的提问来源于stack exchange，提问作者승현정