题目：在一个列表中存储以下元素：apple,grape,banana,pear，现要求将集合进行排序，返回集合中的最大的和最小的元素，并将排序后的结果打印在控制台上，要求的打印输出方法分别为默认toString输出、迭代器输出、for循环遍历输出和增强for循环输出。

package test;
import java.util.*;
public class Pratice3 {
    public static void main(String[] args) {
        // TODO Auto-generated method stub
         List<String> list = new ArrayList<String>();
         list.add("apple");
         list.add("grape");
         list.add("banana");
         list.add("pear");
         Collections.sort(list,new Comparator<String>(){

            @Override
            public int compare(String arg0, String arg1) {
                // TODO Auto-generated method stub
                return arg0.compareTo(arg1);
            }

         });
         System.out.println("最大元素："+list.get(list.size()-1));
         System.out.println("最小元素："+list.get(0));
         System.out.println("***默认toString输出***");
         System.out.println(list);
         System.out.println("***迭代器遍历输出***");
         Iterator<String> it = list.iterator();
         while(it.hasNext()){
             System.out.print(it.next()+"  ");
         }
         System.out.println();
         System.out.println("***for循环遍历输出***");
         for(int i = 0;i<list.size();i++){
            System.out.print(list.get(i)+"  ");
         }
         System.out.println();
         System.out.println("***增强for循环输出***");
         for(String i :list){
             System.out.print(i+"  ");
         }
    }

}
输出：
最大元素：pear
最小元素：apple
***默认toString输出***
[apple, banana, grape, pear]
***迭代器遍历输出***
apple  banana  grape  pear  
***for循环遍历输出***
apple  banana  grape  pear  
***增强for循环输出***
apple  banana  grape  pear