java silver SE17 第7章-42

1. import java.util. Collection;
2.
3. public class A {
4.    public void sample(Collection arg) {
5.       System.out.printin("A");
6.    }
7. }

1. import java.util.Collection;
2. import java.util.List;
3.
4. public class B extends A {
5.   public void sample(Collection arg) {
6.     System.out.println("B");
7.   }
8.   public void sample (List arg) {
9.　　　　System.out.println("C");
10.　}
11.}

1. import java.util.ArrayList;
2. import java.util.List;
3.
4. public class Main {
5.    public static void main(String[] args) {
6
7.       A a1 = new A();
8.       A a2 = new B();
9.       B b1 = new B();
10.
11.      List<String> list = new ArrayList<>();
12.
13.      // do something
14.
15.   } 
16. }