int n=str.length()-3;
while(n>0)
{
str.insert(n,",");
n-=3;
}
while(n>0)
{
str.insert(n,",");
n-=3;
}
2015-10-18
http://www.cnblogs.com/mengdd/archive/2013/02/03/2890923.html 不懂的可以先看看这个
2015-10-12