有关强制转换的Java编译问题

Question

If I have two objects not related to each other. What will happen in the following cases: We have: Object A, Object B

A a = new A();
B b = new B();

1. a = b; \\will compile? will I get an exception?
2. a = (A) b; \\will compile ? afterwards - will I get an exception?

Answer 1

You can simply compile them to get the answer as well.

1. No Won't compile

2. No Won't compile

See Also

• Conversions and Promotions

Answer 2

两者都不会编译，在第二种情况下，只有在编译器可以检查类型的情况下，因此，如果您首先通过Object，您将能够在运行时进行强制转换并获取异常

Answer 3

If the two objects are unrelated you will not be able to cast one to the other. 1. Will not compile. 2. Will compile, but will throw an exception at runtime.

If one object was inherited from the other, then you would be able to cast the one to the other.