Collection复习

package All;

import java.util.ArrayList;
import java.util.Collection;
import java.util.Iterator;
import java.util.Objects;

public class Demon1 {
public static void main(String[] args) {
Collection c = new ArrayList();
System.out.println("集合是不是空的"+c.isEmpty());
System.out.println("集合的长度为"+c.size());

    c.add("jack");
    c.add(123);
    c.add(3.14);
    c.add('a');
    System.out.println("此时集合是否为空"+c.isEmpty());
    System.out.println("此时集合的长度为"+c.size());

    c.remove(123);
    System.out.println("此时的集合长度为"+c.size());

    Iterator it = c.iterator();
    while (it.hasNext()){
        Object o=it.next();
        System.out.println(o);
    }

}

}