test22.java

来自「SCJP认证考试资料」· Java 代码 · 共 11 行

import java.util.*;
class Test22 {
    public static void main(String[] args) {
	Vector<Number> c1 = new Vector<Number>();
	List<Integer> c2 = new Vector<Integer>();
	HashSet<?> c3 = new HashSet<String>();
	Set<? extends Number> c4 = new TreeSet<Number>();
	Set<? super Number> c5 = new TreeSet<Number>();
    }
}