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<String> list=new ArrayList<String>(); 13 list.add("aaa"); 14 list.add("bbb"); 15 list.add("ccc"); 16 System.out.println(listToString(list));//aaa,bbb,ccc 17 } 18 19 public static String listToString(List<String> 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 elements 16 StringBuffer buf = new StringBuffer(256); // Java default is 16, probably too small 17 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 }
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