import java.util.*;
class Cat2 {
private int catNumber;
Cat2(int i) {
catNumber = i;
}
void print() {
System.out.println("Cat number " +catNumber);
}
}
class Dog2 {
private int dogNumber;
Dog2(int i) {
dogNumber = i;
}
void print() {
System.out.println("Dog number " +dogNumber);
}
}
public class CatsAndDogs2 {
public static void main(String[] args) {
Vector cats = new Vector();
for(int i = 0; i < 7; i++)
cats.addElement(new Cat2(i));
// Not a problem to add a dog to cats:
cats.addElement(new Dog2(7));
Enumeration e = cats.elements();
while(e.hasMoreElements())
((Cat2)e.nextElement()).print();
// Dog is detected only at run-time
}
}
出现:
注意：CatsAndDogs2.java 使用了未经检查或不安全的操作。
注意：要了解详细信息，请使用 -Xlint:unchecked 重新编译。
要怎么做啊?
