旧行为不是错误，新行为也不是错误.条件表达式类型的规则变得更加复杂，这在很多情况下都有帮助，而对您的情况并没有真正的伤害.

Neither was the old behavior a bug, nor is the new behavior a bug. The rules for the type of the conditional expression just got more complex, which helps in many cases and doesn't really hurt in yours.

编译器不允许，因为Integer.class 和Float.class 的类型不可比.没有类型 T 会使 Class 成为 Class 和 Class.

The compiler does not allow it because the types of Integer.class and Float.class are incomparable. There is no type T which would make Class<T> a supertype of both Class<Integer> and Class<Float>.