8.2 定义简单泛型类

generic class

package chapter08;
public class Pair<T> {
    private T first;
    private T second;
    public Pair(T f, T s) {
        first = f;
        second = s;
    }
    public T getFirst() {
        return first;
    }
    public T getSecond() {
        return second;
    }
}