多行字符串文本块

String msg;
switch (day) {
    case MONDAY:
        msg = "Start";
        break;
    case FRIDAY:
        msg = "End";
        break;
    default:
        msg = "Mid";
}

if (obj instanceof String) {
    String s = (String) obj;
    System.out.println(s.length());
}

// Must add default even though
// all cases are covered
double area(Shape s) {
    if (s instanceof Circle c)
        return Math.PI * c.r() * c.r();
    else if (s instanceof Rect r)
        return r.w() * r.h();
    else throw new IAE();
}