如何初始化inputStream[duplicate]

Question

我正在尝试初始化InputStream，但它不允许我。我已经能够初始化outputStream。

public void readData() {
  String fileName = "clinicData.txt";
  Scanner inputStream;
  System.out.println("The file " + fileName +"\ncontains the following line:\n");
  
  try {
      inputStream = new Scanner (new File (fileName));
  } catch (FileNotFoundException e) {
      System.out.println("Error: opening the file " +fileName);
      System.exit(0);
  }
  while (inputStream.hasNextLine()) {
      String line = inputStream.nextLine();
      System.out.println (line);
  }
  inputStream.close();
}

Answer 1

您要执行以下操作：

try (Scanner inputStream = new Scanner(new File(fileName))) {
    while (inputStream.hasNextLine()) {
        String line = inputStream.nextLine();
        System.out.println(line);
    }
} catch (FileNotFoundException e) {
    System.out.println("Error: opening the file " +fileName);
    System.exit(0);
}

• 扫描器输入流；在try块中初始化，但是，不能保证初始化成功，您稍后将尝试在while循环中访问此类实例，这将是错误的。在try块内移动while循环。
• 扫描器是自动关闭的，因此您可以使用try-with-resources并省略InputStream.Close()