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。
1package test; 2import java.util.*; 3public class Pratice3 { 4 public static void main(String[] args) { 5 // TODO Auto-generated method stub 6 List<String> list = new ArrayList<String>(); 7 list.add("apple"); 8 list.add("grape"); 9 list.add("banana"); 10 list.add("pear"); 11 Collections.sort(list,new Comparator<String>(){ 12 13 @Override 14 public int compare(String arg0, String arg1) { 15 // TODO Auto-generated method stub 16 return arg0.compareTo(arg1); 17 } 18 19 }); 20 System.out.println("最大元素："+list.get(list.size()-1)); 21 System.out.println("最小元素："+list.get(0)); 22 System.out.println("***默认toString输出***"); 23 System.out.println(list); 24 System.out.println("***迭代器遍历输出***"); 25 Iterator<String> it = list.iterator(); 26 while(it.hasNext()){ 27 System.out.print(it.next()+" "); 28 } 29 System.out.println(); 30 System.out.println("***for循环遍历输出***"); 31 for(int i = 0;i<list.size();i++){ 32 System.out.print(list.get(i)+" "); 33 } 34 System.out.println(); 35 System.out.println("***增强for循环输出***"); 36 for(String i :list){ 37 System.out.print(i+" "); 38 } 39 } 40 41} 42输出： 43最大元素：pear 44最小元素：apple 45***默认toString输出*** 46[apple, banana, grape, pear] 47***迭代器遍历输出*** 48apple banana grape pear 49***for循环遍历输出*** 50apple banana grape pear 51***增强for循环输出*** 52apple banana grape pear