Question

我在java考试，当我学习时，我看到了这个练习，我试着解决它，但我发现有些困难所以请帮助我请考虑实用程序中方法的以下注释，标题和部分代码加密类称为Atbash。

    /**
    * Prompts the user for the pathname of a source .txt file to encrypt.
    * Prompts the user for the pathname of a destination .txt file
    * to which the encrypted text will be written.
    * The pathnames are then used to create two File objects.
    * The method then attempts to open streams on both files, one to
    * read from the source file, the other to write to the destination file.
    *
    * The method then reads from the read stream a line at a time.
    * Each line read is converted to uppercase using the message
    * toUpperCase(). The method then constructs an encrypted string
    * into which all the alphabetic characters from the line are
    • substituted by their atbash equivalent, however any numeric or
    * punctuation characters are simply added unchanged to the encrypted
    * string. After each string is constructed it is written to the write
    * stream followed by a newline character.
    */
    public static void encryptFile()
    {
    OUDialog.alert("Please choose a file to encrypt");
    String pathname = OUFileChooser.getFilename();
    File aFile = new File(pathname);
    OUDialog.alert("Please give a file name for the encrypted file");
    String pathname2 = OUFileChooser.getFilename();
    File bFile = new File(pathname2);
    BufferedReader bufferedFileReader = null;
    BufferedWriter bufferedFileWriter = null;

    try
    {
    String currentLine;
    bufferedFileReader = new BufferedReader(new FileReader(aFile));
    bufferedFileWriter = new BufferedWriter(new FileWriter(bFile));
    String codedLine = "";
    char currentChar;
    String alphabet ="ABCDEFGHIJKLMNOPQRSTUVWXYZ";
    String mirror ="ZYXWVUTSRQPONMLKJIHGFEDCBA";
    currentLine = bufferedFileReader.readLine();
    while (//Boolean condition to be written as your answer for part (i))
/**this what I do while(currentLine!=null)*/

    {
    //Statement block to be written as your answer for part (ii)

    }
    }
    catch (Exception anException)
    {
    System.out.println("Error: " + anException);
    }
    finally
    {
    try
    {
    //Statement block to be written as your answer for part (iii)
  /* bufferedFileReader.close();
   *  bufferedFileWriter.close();
   */

    }
    catch (Exception anException)
    {
    System.out.println("Error: " + anException);
    }
    }
    }

（i）在上述方法中记下while循环的布尔条件。

while(currentLine= bufferedFileReader.readLine()!= null)
    {

    }

（ii）在上述方法中编写while语句块的代码。这应该确保当while循环终止时，目标.txt文件包含源.txt文件的加密版本。你的代码应该使用变量bufferedFileReader，bufferedFileWriter，currentLine，codedLine， currentChar，字母和镜子。您可能会发现以下两个来自String协议的消息很有用： charAt（int），它返回参数指定的索引处的char值和indexOf（char）返回第一次出现的索引接收器内的参数。

（iii）编写最终try块的代码。

bufferedFileReader.close();
 bufferedFileWriter.close();

Answer 1

下面

/**this what I do while(currentLine!=-1)*/

由于currentLine是String，因此您无法将其与int值进行比较。您应该检查BufferedReader.readLine()的Javadoc以查看它是如何表示没有更多数据要读取，然后相应地修复条件。

流，Java中的缓冲区

1 个答案: