Question

我需要编写一些东西来读取“投票：”行的某个文件，然后检查它后面的数字。然后它需要取这个数字，添加一个，然后将其打印回文件。以下是我到目前为止的情况：

 try{
       File yourFile = new File(p + ".vote");
           if(!yourFile.exists()) {
               yourFile.createNewFile();
           } 
       FileOutputStream oFile = new FileOutputStream(yourFile, false); 
       this.logger.info("A vote file for the user " + p + " has been created!");
 } catch(Exception e) {
     this.logger.warning("Failed to create a vote file for the user " + p + "!");

那么，我该怎么做？

Answer 1

您应该使用Scanner类来读取文件，我认为这对您来说会更容易。

实施例

File file = new File("k.vote");

try {
    Scanner scanner = new Scanner(file);
} catch(FileNotFoundException e) { 
    //handle this
}

//now read the file line by line...

while (scanner.hasNextLine()) {
    String line = scanner.nextLine();
    String[] words = line.split(" ");
    //now loop through your words and see if you find voted: using the substring function
    for (int i = 0; i < words.length(); i++) {
        if (words[i].length() > 5) {
            String subStr = words[i].substring(0,5);
            if (subStr.compareTo("voted:") == 0) {
                //found what we are looking for
                String number = words[i].substring(6, words[i].length()-1);
            }
        }
    }
}

至于在文件中更新这个的最有效方法 - 我会说保留你所在行数的计数器，直到找到你想要改变的数字。然后打开要写入的文件，跳过 x 行数，并像上面那样解析字符串并更新变量。

读取文件然后在Java中执行操作

1 个答案: