抛出异常的编译错误

Question

public class A {
    public void f(A a) {
        System.out.print("in A ");
    }
}

public class B extends A {

    public static void main(String[] args) {
        B b = new B();
        A a = new A();
        b.f(b);
        b.f(a);
    }
}

为什么在B中添加如下方法class会出现编译错误？

众所周知，如果方法抛出某些东西，则不必在方法头中声明...

public void f(A a) { 
    System.out.println("in B"); 
    throw new java.io.IOExeption();
}

Answer 1

It's known that if method throws something, it doesn't have to be declared in the method header

这仅适用于未经检查的异常。您的方法抛出 IOException，这是一个 已检查异常 ，因此您必须捕获它或声明抛出它，否则编译将失败。

抛出异常的编译错误

compilation error with throwing exception

java

compilation

throws