import java.util.*; class CollectionDemo{ public static void main(String[]args){ iterator(); } //增加元素 public static void add(){ ArrayList al = new ArrayList(); ArrayList al1 = new ArrayList(); al.add("java01"); al.add("java02"); al.add("java03"); al.add("java04"); al1.add("java05"); print(al); //增加所有元素 al1.add(al); print(al1); } //清空容器 public static void clear(){ ArrayList al = new ArrayList(); //ArrayList al1 = new ArrayList(); al.add("java01"); al.add("java02"); al.add("java03"); al.add("java04"); al.clear(); print(al); } //包含元素 public static void contains(){ ArrayList al = new ArrayList(); //ArrayList al1 = new ArrayList(); al.add("java01"); al.add("java02"); al.add("java03"); al.add("java04"); al.contains(al); print(al); } //获取迭代器 public static void iterator(){ /*Iterator it = al.iterator();//al.iterator()子类对象，接口通过子类对象实例化 while(it.hasNext()){ print(it.next()); }//这个循环耗内存 */ for(Iterator it = al.iterator();true ==it.hasNext();){ print(it.next()); } } //打印 public static void print(Object obj){ System.out.println(obj); } } |
