问题

public static void main(String[] args) throws IOException {
    File numbers = new File("C:\\numbers.txt");
    File positiveNumbers = new File("C:\\positive_numbers.txt");
    File negativeNumbers = new File("C:\\negative_numbers.txt");

    try (
        BufferedWriter wr = new BufferedWriter(new FileWriter(numbers));
        BufferedReader rd = new BufferedReader(new FileReader(numbers));
        BufferedWriter brNegative = new BufferedWriter(new FileWriter(negativeNumbers));
        BufferedWriter brPositive = new BufferedWriter(new FileWriter(positiveNumbers));
    ) {
        if (numbers.exists()) {
            for (int i = 1; i <= 100; i++) {
                wr.write(i + " ");
            }
            for (int a = -1; a >= -100; a--) {
                wr.write(a + " ");
            }

            wr.flush();  // Important: flush the buffer to write the changes to the file

            String line = rd.readLine();
            String[] numbersArray = line.split(" ");
            for (String numStr : numbersArray) {
                int num = Integer.parseInt(numStr);
                if (num > 0) {
                    brPositive.write(num + " ");
                } else if (num < 0) {
                    brNegative.write(num + " ");
                }
            }

            brPositive.flush();  // Flush the buffer to write the positive numbers
            brNegative.flush();  // Flush the buffer to write the negative numbers
        }
    } catch (FileNotFoundException e) {
        e.printStackTrace();
    }
}

public static void main(String[] args) throws IOException {
File numbers = new File("C:\\numbers.txt");
File positivNumbers = new File("C:\\positivnumbers.txt");
File negativNumbers = new File("C:\\negativnumbers.txt");
try (
BufferedWriter wr = new BufferedWriter(new FileWriter(numbers));
BufferedReader rd = new BufferedReader(new FileReader(numbers));
BufferedWriter brnegativ = new BufferedWriter(new FileWriter(negativNumbers));
BufferedWriter brpositiv = new BufferedWriter(new FileWriter(positivNumbers));) {
if (numbers.exists()) {
for (int i = 0; i <= 100; i++) {
wr.write(String.valueOf((i) + " "));
}
for (int a = -1; a >= -100; a--) {
wr.write(((a) + " "));
}
String line = rd.readLine();
while (line != null) {
brpositiv.write(line);
}
}
} catch (FileNotFoundException e) {
e.printStackTrace();
}
}

答案1

得分: 3

在写入操作之后，您需要关闭 wr，这样内存中的所有数据都会刷新到文件中。在关闭之后，您可以重新打开它进行读取。因此，在您的代码中，您打开 rd 太早了。

try (BufferedWriter wr = new BufferedWriter(new FileWriter(numbers));) {
    for (int i = 0; i <= 100; i++) {
        wr.write(String.valueOf((i) + " "));
    }
    for (int a = -1; a >= -100; a--) {
        wr.write(((a) + " "));
    }
} catch (IOException e) {
    e.printStackTrace();
}
// 文件在 try-with-resources 中被关闭...

// ... 所以现在我们可以打开它进行读取：
try (BufferedReader rd = new BufferedReader(new FileReader(numbers));
     BufferedWriter brnegativ = new BufferedWriter(new FileWriter(negativNumbers));
     BufferedWriter brpositiv = new BufferedWriter(new FileWriter(positivNumbers));) {
        String line = rd.readLine();
        while (line != null) {
            brpositiv.write(line);
           // TODO : 分割逻辑
        }
} catch (IOException e) {
    e.printStackTrace();
}

   try (BufferedWriter wr = new BufferedWriter(new FileWriter(numbers));) {
for (int i = 0; i <= 100; i++) {
wr.write(String.valueOf((i) + " "));
}
for (int a = -1; a >= -100; a--) {
wr.write(((a) + " "));
}
} catch (IOException e) {
e.printStackTrace();
}
// file is closed by try-with-resources ...
// ... so now we can open it for read:
try (BufferedReader rd = new BufferedReader(new FileReader(numbers));
BufferedWriter brnegativ = new BufferedWriter(new FileWriter(negativNumbers));
BufferedWriter brpositiv = new BufferedWriter(new FileWriter(positivNumbers));) {
String line = rd.readLine();
while (line != null) {
brpositiv.write(line);
// TODO : split logic
}
} catch (IOException e) {
e.printStackTrace();
}