java - 为什么我在 Java 中读取一个简单的文本文件时在 do while 循环中的 If 语句中得到 NullPointerException

Question

我是 Java 的新手，我有很多与文本有关的工作，我有一个想法来制作一个简单的程序来完成我的工作。我收到错误 Exception in thread "main"java.lang.NullPointerException at com.text.work.Main.main(Main.java:25)

public class Main {

public static void main(String[] args) throws IOException {
    int someNumber = 0;
    PrintWriter saveFileOne = new PrintWriter("save.txt");
    PrintWriter saveFileTwo = new PrintWriter("otherThings.txt");
    FileReader fileReader = new FileReader("read.txt");
    BufferedReader bufferedReader = new BufferedReader(fileReader);
    String word = bufferedReader.readLine();


    do {
        word = bufferedReader.readLine();

        if (word.toString().equals("true")) { //this is line 25
            saveFileOne.println("No: " + ++someNumber + " = " + word);
        } else {
            saveFileTwo.println("Yes: " + someNumber + " = " + word);
        }

    } while (word != null);
    saveFileOne.close();
    saveFileTwo.close();
    bufferedReader.close();
    System.out.println("Done!");
}

}

Answer 1

来自BufferedReader#readLine()文档:

Returns: A String containing the contents of the line, not including any line-termination characters, or null if the end of the stream has been reached

这意味着您显然已经到达了流的末尾。

如果我是你，我会用 while 改变循环。

while ((word = buffer.readLine()) != null) {
 ..
}