Question

我正在尝试将我的java控制台输出写入桌面上的.txt文件。但是当该方法启动时，我有控制台输出和txt文件被创建，但它是空的，我意识到BufferedReader（in）不工作...（因为“ok1 - i”语句）

问题是为什么？或者我的代码错在哪里？这是我的代码，所以你可以看到并运行它

   package noobxd;

   import java.io.BufferedReader;
   import java.io.BufferedWriter;
   import java.io.FileWriter;
   import java.io.IOException;
   import java.io.InputStreamReader;
   import java.util.Random;

   public class Main {

public static void main(String[] args) throws IOException {
    String path = "C:\\Users\\Mario\\Desktop\\output.txt";

    generate_codes();

    writetxt(path);
}

private static void writetxt(String path) throws IOException {
    BufferedReader in = new BufferedReader(new InputStreamReader(System.in));

    BufferedWriter out = new BufferedWriter(new FileWriter(path));
    try {
        String inputLine;
        inputLine = "";
        int i=0;
        System.out.println("Starting");
        while (!inputLine.isEmpty()){
            System.out.println("ok1"+i);
            inputLine = in.readLine();
            System.out.println("ok2"+i);
            out.write(inputLine);
            System.out.println("ok3"+i);
            out.newLine();
            System.out.println("ok4"+i);
            i++;
        }
        System.out.print("Write Successful");
    } catch (IOException e1) {
        System.out.println("Error during reading/writing");
    } finally {
        out.close();
        in.close();
    }
}

private static void generate_codes() {
    Random rnd = new Random();
    for (int i = 0; i < 30; i++) {
        int code = rnd.nextInt(201) + 100;
        int students = rnd.nextInt(31) + 40;
        int j = rnd.nextInt(4);
        String type = new String();
        switch (j) {
            case 0:
                type = "Theory";
                break;
            case 1:
                type = "Lab";
                break;
            case 2:
                type = "Practice";
                break;
            case 3:
                type = "Exam";
                break;
        }
        System.out.println("TEL" + code + "-TopicNumber" + i + "-" + students + "-" + type);

    }
}
}

感谢您的时间，请帮我解决问题。

Answer 1

String inputLine;
inputLine = "";
...
while (!inputLine.isEmpty())  // this is false and so the loop is not executed

将来，请学习使用调试工具，并仔细阅读您的代码。如果您在EOF之前尝试阅读，请使用

while ((inputLine = in.readLine()) != null) {
    ...
}

Answer 2

如果你想保持循环直到用户在控制台输入一个空行，你可能想要像

这样的东西

while (true) {
        System.out.println("ok1"+i);
        inputLine = in.readLine();
        if (inputLine.isEmpty()) 
            break;
        // the rest of your loop
}

Answer 3

你可能应该这样做：

inputLine = in.readLine();
while (inputLine != null && !inputLine.isEmpty()){
    System.out.println("ok1"+i);
    System.out.println("ok2"+i);
    out.write(inputLine);
    System.out.println("ok3"+i);
    out.newLine();
    System.out.println("ok4"+i);
    i++;
    inputLine = in.readLine();
}

将控制台输出写入.txt文件

3 个答案: