如何使用bash将文件重定向为Java程序的输入？ [英] How to redirect a file as an input to Java program with bash?

问题描述

我的代码大致如下所示：

My code roughly looks like this:

InputStreamReader isReader = new InputStreamReader(System.in);
BufferedReader bufReader = new BufferedReader(isReader);
while (true) {
    try {
        String inputStr = null;
        if ((inputStr=bufReader.readLine()) != null) {
            //DO SOMETHING
        }
        else {
            System.out.println("input is null");
        }
    }
    catch (Exception e) {
        //DO SOMETHING
    }
}

当我跑步时

 java -classpath ../src test.TestProgram < filename

它处理文件中的第一行，但它会一直打印输入为空并且永远不会进入第二行。

it process the first line in the file well, but it keeps printing input is null and never goes to the second line.

如何修改我的程序以告诉它让错误输入去掉到下一行？

How can I modify my program to to tell it let the error input go and go to the next line?

PS：我需要进行的文件如下所示：

PS: the file I need to precess is like below:

111111111
111111112
111111113
...

我试过

java -classpath ../src test.TestProgram < filename
echo `cat filename` | java -classpath ../src test.TestProgram
java -classpath ../src test.TestProgram <<< `cat filename`

他们都失败了

我的错...我在循环中放了BufferedReader bufReader = new BufferedReader（new InputStreamReader（System.in））谢谢大家！

推荐答案

您的代码实际上很好，它适用于Mac OSX Java 1.6.0。我做了一些小改动：

Your code is actually fine and it works for me on Mac OSX Java 1.6.0. I made a few minor changes:

  public static void main(String[] args) {
    InputStreamReader isReader = new InputStreamReader(System.in);
    BufferedReader bufReader = new BufferedReader(isReader);
    while (true) {
      try {
        String inputStr = null;
        if ((inputStr = bufReader.readLine()) != null) {
          System.out.println(inputStr);
        } else {
          System.out.println("input is null");
          return; //end on first null
        }
      } catch (Exception e) {
        e.printStackTrace();
      }
    }
  }

我跑：

java Test.java < data.txt

并输出：

111111111
111111112
111111113
input is null

你是如何制作输入文件的？也许你的行结尾是非标准的？

How did you make your input file? Perhaps your line endings are non-standard?

这是你的代码清理了一下：

Here is your code cleaned up a bit:

  public static void main(String[] args) {
    BufferedReader bufReader = new BufferedReader(new InputStreamReader(System.in));
    String inputStr = null;
    try {
      while ((inputStr = bufReader.readLine()) != null) {
        System.out.println(inputStr);
      }
    } catch (Exception e) {
      e.printStackTrace();
    }
    System.out.println("end of file");
  }

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