1. 写一程序，将"d","b","a","c"依次存入list中，并按照abcd的顺序用迭代器输出

package number;

import java.util.ArrayList;
import java.util.Iterator;
import java.util.List;
import java.util.Set;
import java.util.TreeSet;

public class CharSort {

/**
* @param args
*/
public static void main(String[] args) {
// TODO Auto-generated method stub
List<String> list=new ArrayList<String>();
list.add("d");
list.add("b");
list.add("a");
list.add("c");
list.add("1");
int len=list.size();
for(String s:list){
System.out.print(s.toString());
}
System.out.println();
System.out.println("list的长度为:"+len);
Set<String> s=new TreeSet<String>(list);
        Iterator it = s.iterator();
        for(;it.hasNext();){
        System.out.print(it.next());
        }
}

}