使用BufferedReader读取多行整数时发生java错误

Question

我得到一个例外：

Exception in thread "main" java.lang.NumberFormatException: For input string: "55 45 65 88 "
    at java.lang.NumberFormatException.forInputString(Unknown Source)
    at java.lang.Integer.parseInt(Unknown Source)
    at java.lang.Integer.valueOf(Unknown Source)

使用此代码时：

BufferedReader br = new BufferedReader(new InputStreamReader(System.in));

String line = br.readLine();
int noOfStudents = Integer.parseInt(line); //firstline contains 1 integer.

ArrayList <Integer> marks = new ArrayList<Integer>();

line = br.readLine(); //second line contains a line of integers

StringTokenizer tokens = new StringTokenizer(line, "\\s+");
// to break the line into tokens 

while (tokens.hasMoreTokens())
{
    marks.add(Integer.valueOf(tokens.nextToken())); //error here
    //when I am converting tokens into integers its giving error
}

样本输入：

4
55 45 65 88 (here, when I press enter it gives me the above stated errors)

Answer 1

StringTokenizer不支持正则表达式

StringTokenizer tokens = new StringTokenizer(line, "\\s+");
// This will look for literal "\s+" string as the token.

用这个代替

StringTokenizer tokens = new StringTokenizer(line, " "); // Just a space.

Edit:正如@MasterOdin所指出的，StringTokenizer的默认分隔符是一个空格" "。因此，下面的方法也同样适用

StringTokenizer tokens = new StringTokenizer(line);

Answer 2

您可以选择以下简单方法：

String []m=br.readLine().split(" "); // split the line delimited with space as array of string.
 for(int i=0;i<m.length;i++){
    marks.add(Integer.valueOf(m[i]));  // add to the marks array list
 }

编辑：根据T.G

for (String s : br.readLine().split("\\s+")) {
   marks.add(Integer.valueOf(s));
}