Question

我正在读取文件中的行，我相信一旦我读完所有行，就会因为我的while循环条件而出现异常。

Exception in thread "main" java.lang.NullPointerException
    at liarliar.main(liarliar.java:79)

......代码......

// read the first line of the file
iNumMembers = Integer.parseInt(br.readLine().trim()); 

// read file
while ((sLine = br.readLine().trim()) != null) {

    // extract the name and value 'm'
    String[] split = sLine.split("\\s+");
    sAccuser = split[0];
    iM = Integer.parseInt(split[1]);
    saTheAccused = new String[iM];

    for (int i = 0; i < iM; i++) {
        saTheAccused[i] = br.readLine().trim();
    }

    // create member
    // initialize name and number of members being accused
    Member member = new Member();
    member.setName(sAccuser);
    member.setM(iM);
    member.setAccused(saTheAccused);

    veteranMembers.add(member);
}

for循环内部必须读取几行，所以如果读取文件的最后一行，那么while将尝试readLine()，这将失败，因为整个文件已被读取。那么BufferedReader readLine()如何工作以及如何安全地退出while循环呢？

感谢。

Answer 1

readLine()在EOF上返回null，并且您尝试在空引用上调用trim()。将调用移至循环内的trim()，如

// read file
while ((sLine = br.readLine()) != null) {

    // extract the name and value 'm'
    String[] split = sLine.trim().split("\\s+");

BufferedReader如何跟踪已读取的行？

1 个答案: