Question

我从讲座中得到了以下问题，并告诉他答案是iii.It compiles, runs and prints the string “Hello”但我相信答案是i. It has a compilation error这是因为B级进口packA的方式是不正确，而应该是导入packA.A或packA。* 我的问题是 - 这是一个错字还是可以运行并打印“你好”

   J.   Assuming the class A and class B given below are defined in different packages, packA and packB.

    package packA;
    public class A {
        protected void msg() {
            System.out.println("Hello");
        }
    }

    package packB;
    import packA;
    class B extends A {
        public static void main(String[] args) {
            B obj = new B();
            obj.msg();
        }
    }


    which of the following is correct about the class B?

    i.  It has a compilation error
    ii. It has a run time error
    iii.It compiles, runs and prints the string “Hello”
    iv. None of the above

Answer 1

导入确实存在错误。它应该是Vector <- c("alex" ,"IT") Tst <- data.frame( name.charcher(), major.charachter()) sqldf( c(" insert into Tst values (" , Vector[1] , "," ,Vector[2] , ")" , "select * from main.Tst "))。

导入包而不指定类

1 个答案: