public class SyncDemo4 {
public static void main(String[] args) {
Collection c = new ArrayList();
c.add("one");
c.add("two");
c.add("three");
c.add("four");
c.add("five");
System.out.println(c);
/**
* 返回元素个数
*/
int size = c.size();
System.out.println("元素个数"+size);
/**
* boolean isEmpty()
*
*/
boolean isEmpty = c.isEmpty();
System.out.println("是空集"+isEmpty);
/**
* void clear()
* 清空所有元素
*/
c.clear();
System.out.println("集合已清空");
isEmpty = c.isEmpty();
System.out.println("是空集"+isEmpty);
size = c.size();
System.out.println("元素个数"+size);
}
}
集合中的各种方法
Guess you like
Origin blog.csdn.net/sinat_33940108/article/details/121282432
Ranking