最新回答 / 慕仙7584962
byte[] str=s.getBytes(); for (int i=0;i<str.length;i++) { if (str[i]=='a'){ num++; }
2019-07-08
int length = str.length();
for(int i = length;i > 0;i = i-3){
str.insert(i,",");
}
for(int i = length;i > 0;i = i-3){
str.insert(i,",");
}
2019-07-03
int index = fileName.lastIndexOf(".");
// 获取文件的后缀
String prefix = fileName.substring(fileName.lastIndexOf(".") + 1);
// 获取文件的后缀
String prefix = fileName.substring(fileName.lastIndexOf(".") + 1);
2019-07-03
