1 import java.util.ArrayList; 2 import java.util.List; 3 /** 4  * 集合操作 5  * @author intrl 6  * @date 2010-12-15 7  * @version 1.0 8  */ 9 public class Test {10  11     public static void main(String[] args) {12         List
     
       list=new ArrayList
      
       ();13         list.add("aaa");14         list.add("bbb");15         list.add("ccc");16         System.out.println(listToString(list));//aaa,bbb,ccc17     }18      19     public static String listToString(List
       
         stringList){20         if (stringList==null) {21             return null;22         }23         StringBuilder result=new StringBuilder();24         boolean flag=false;25         for (String string : stringList) {26             if (flag) {27                 result.append(",");28             }else {29                 flag=true;30             }31             result.append(string);32         }33         return result.toString();34     }35 }
       
      
     

 方法二:

1 这代码太垃圾了  2 为什么不  4 int length = arr.length ; 5 StringBuffer buf = new StringBuffer(""); 6 if(length > 0){ 7     buf.append(arr[0]); 8 } 9 for(int i = 1 ; i < length ; i++){10    buf.append(',');11    buf.append(arr[i]);12 }

 方法三:

 apache common包下的StringUtils的join方法:

 StringUtils.join(list, ",");

 以下其源码:

1 public static String join(Iterator iterator, String separator) { 2   3         // handle null, zero and one elements before building a buffer 4         if (iterator == null) { 5             return null; 6         } 7         if (!iterator.hasNext()) { 8             return EMPTY; 9         }10         Object first = iterator.next();11         if (!iterator.hasNext()) {12             return ObjectUtils.toString(first);13         }14  15         // two or more elements16         StringBuffer buf = new StringBuffer(256); // Java default is 16, probably too small17         if (first != null) {18             buf.append(first);19         }20  21         while (iterator.hasNext()) {22             if (separator != null) {23                 buf.append(separator);24             }25             Object obj = iterator.next();26             if (obj != null) {27                 buf.append(obj);28             }29         }30         return buf.toString();31     }