Java_基础—集合的遍历之集合转数组遍历

package com.soar.collection;

import java.util.ArrayList;
import java.util.Collection;

import com.soar.bean.Student;

@SuppressWarnings({ "rawtypes", "unchecked" })
public class Demo3_Collection {
/*
     * * A:集合的遍历
        * 其实就是依次获取集合中的每一个元素。
     * B:案例演示
        * 把集合转成数组，可以实现集合的遍历
        * toArray()
 */
    public static void main(String[] args) {
        //demo1();
        Collection c = new ArrayList();
        c.add(new Student("张三",23));    //Object obj = new Student("张三"，23)；
        c.add(new Student("李四",25));
        c.add(new Student("王五",18));
        c.add(new Student("赵六",26));

        Object[] arr = c.toArray();     //将集合转换成数组
        for (int i = 0; i < arr.length; i++) {
            //System.out.println(arr[i]);
            Student s = (Student)arr[i];    //向下转型
            System.out.println(s.getName()+"..."+s.getAge());   
        }
    }

private static void demo1() {
    Collection c = new ArrayList();
    c.add("a");
    c.add("b");
    c.add("c");
    c.add("d");

    Object[] arr = c.toArray();     //将集合转换成数组
    for (int i = 0; i < arr.length; i++) {
        System.out.println(arr[i]);
    }
}

}