1
Collection c=new ArrayList();
c.add("a");
c.add("b");
c.add("c");
c.add("d");
// c.remove("b"); //删除指定元素
// c.clear(); //清空集合
// System.out.println(c.contains("b")); //是否包含b
// System.out.println(c.isEmpty()); //是否为空
System.out.println(c.size()); //获取元素个数
System.out.println(c);
2
Collection c=new ArrayList();
boolean b1=c.add("abc");
boolean b2=c.add(true);
boolean b3=c.add(100);
boolean b4=c.add(new Student("zhangsan",23));
System.out.println(b1);
System.out.println(b2);
System.out.println(b3);
System.out.println(b4);
System.out.println(c.toString());