JFileChooser和.txt文件解析问题

Question

我在解决CCE时遇到问题。此分配要求用户在运行时打开.txt文件，然后让编译器 对特定正则表达式执行后台解析，以确定它们是否匹配或不匹配（例如，ACC或REJ），但捕获是该用户必须用JFileChooser打开该文件。我已经做了大量的阅读和 研究发布之前，问题似乎是 JFileChooser，据我了解使用java.io.File本身，似乎 只允许扫描仪解析输入的.txt文件在此场景。

http://docs.oracle.com/javase/1.5.0/docs/api/java/io/class-use/File.html

所以，当我单独使用扫描器读取文本的所有行的文件 在它的编译“，但所有的控制台输出表现为，例如，“空 空空空空” （例如，如果文件中有五行文字）。 为了方便起见，下面是.txt文件的一个例子，将被认为是可接受的 （或ACC，速记）：EDIT这个例子中应具有的每个印刷在单独的行

S中的规则：AB 甲：0A 答：E B：1B B：è

我提供我的源代码。请注意，charSequences只是Scanner/BR必须解析的可行 正则表达式。此外，如果任何给定的行拒绝（REJ， 简写），我们需要提醒用户，然后立即终止。显然 我不明白这些类以及我以为我做了...也许我需要 使用类似FileReader的东西，我走的基础开始，但我只是 非常沮丧与Java IO的复杂性一般。这只是令人沮丧的 因为我把所有这些工作和努力，并很少有任何事情来显示它。

import java.io.BufferedReader; 
import java.io.BufferedWriter; 
import java.io.File; 
import java.io.FileNotFoundException; 
import java.io.FileReader; 
import java.io.FileWriter; 
import java.io.IOException; 
import java.io.Reader; 
import java.util.*; 
import java.util.regex.Matcher; 
import java.util.regex.Pattern; 
import javax.swing.JFileChooser; 
import javax.swing.JOptionPane; 

public class Simplified 
{ 


public Simplified() throws Exception 
{ 
    readLines(); 
} 

public void readLines() throws Exception 
{ 

    //MUST prompt user to use JFileChooser 
    JFileChooser ranFi = new JFileChooser(); 
    //approve condition 
    if(ranFi.showOpenDialog(null)==JFileChooser.APPROVE_OPTION) 
    { 
     //get selected file 
     Comparable<File> file = ranFi.getSelectedFile(); 
     //create a bufferedReader for the file 
     //BufferedReader br = new BufferedReader((Reader) file); 
     BufferedReader br = null; 

     //create local String object the refer to file's current line 
     String currentLine; 

     /************************** 
     * Length(LHS,RHS) = 1,1 
     * --CharSequence compilations 
     * ****************************** 
     */ 
     //ACC 
     CharSequence fp100 = "[S][:][A-Ze0-1]"; 
     //ACC iff is NOT the very first line of text file 
     CharSequence fp101 = "[A-Z&&[^S]][:][A-Ze0-1]"; 


     /************************** 
     * Length(LHS,RHS) = 1,2 
     * --CharSequence compilations 
     * ****************************** 
     */ 
     //ACC 
     CharSequence fp200 = "[S][:][A-Z0-1][A-Z0-1]"; 
     //ACC iff is NOT the very first line of text file 
     CharSequence fp201 = "[A-Z&&[^S]][:][A-Z0-1][A-Z0-1]"; 

     /************************** 
     * Length(LHS,RHS) = 1,3 
     * --CharSequence compilations 
     * ****************************** 
     */ 
     //ACC 
     CharSequence fp300 = "[S][:][A-Z0-1][A-Z0-1][A-Z0-1]"; 
     //ACC iff is NOT the very first line of text file 
     CharSequence fp301 = "[A-Z&&[^S]][:][A-Z0-1][A-Z0-1][A-Z0-1]"; 

     /** 
     * Length(LHS,RHS) = 1,4 
     * --CharSequence compilations 
     * ****************************** 
     */ 

     //REJ 
     CharSequence fp400 = "[.][.][.][.][.][.]"; 


     //create a Scanner for the file 
     Scanner text = new Scanner((Readable) file); 

     try 
     { 
      br = new BufferedReader((Reader) file); 
      //while there are still lines to be read in the file 
      //where currentLine = present line of the bufferedReader 
      while((currentLine = br.readLine()) != null) 
      { 

       //while the scanner still has lines to read in the file 
       while(text.hasNext()) 
       { 


       //to remove trailing whitespace in the file, starting 
       //@ the first line in the text file... 
       String trimStartLine = currentLine.trim(); 

       //ALL feasible ACC permutations for starting line 
       if(trimStartLine.contains(fp100)||trimStartLine.contains(fp200)||trimStartLine.contains(fp300)) 
       { 
        System.out.println("first line valid..."); 


       } 
       //ALL feasible REJ permutations for starting line 
       else if(!trimStartLine.contains(fp100)||!trimStartLine.contains(fp200)||!trimStartLine.contains(fp300)) 
       { 
        System.out.println("invalid first line..." + 
          "...terminating"); 
        System.exit(0); 
       } 

       //once again removing trailing whitespace in the file, 
       //this time trimming the whitespace in the second line 
       //of the file, provided that iff the first line of the 
       //file was valid to begin with... 
       String trim2ndLine = currentLine.trim(); 

       //permutations have now increased to 6 since "[S]" isn't 
       //technically required for ANY line other than the first line 
       if(trim2ndLine.contains(fp100)||trim2ndLine.contains(fp101)||trim2ndLine.contains(fp200)|| 
         trim2ndLine.contains(fp201)||trim2ndLine.contains(fp300)||trim2ndLine.contains(fp301)) 
       { 
        System.out.println("2nd line valid..."); 

        //only included two line checks for now... 
        //as of now if the first two lines are valid 
        //then print out the remaining lines in the 
        //file... 
        System.out.println(text.nextLine()); 

       } 
       else if(!trim2ndLine.contains(fp100)||!trim2ndLine.contains(fp101)||!trim2ndLine.contains(fp200)|| 
         !trim2ndLine.contains(fp201)||!trim2ndLine.contains(fp300)||!trim2ndLine.contains(fp301)) 
       { 
        System.out.println("invalid 2nd line..." + 
          "...terminating"); 
        System.exit(0); 
       } 
       else 
       { 
        System.out.println("no file was selected"); 
       } 

      }//end of inner while 
      }//end of outer while 
     }//end of try 
       catch (Exception ex) 
       { 
        System.out.println(ex.getMessage()); 
       } 
       finally 
       { 
        try 
        { //close text while lines remain, 
         //valid or not... 
         if(br != null && text != null){ 
          br.close(); 
          text.close(); 
         } 
        } 
        catch (Exception ex) 
        { 
        } 
       }//end of finally 
     System.out.println("end of file successfully reached..."); 
    }//end of approve option 
}//end of method 




public static void main(String[] args) throws Exception 
{ 
    Simplified mn = new Simplified(); 
    mn.readLines(); 
}//end of main 

}//end of Simplified.java 

底线是，无论在源代码中也没有我的扫描仪和BufferedReader对象的类型转换的位置，我总是得到一个CCE。任何帮助将是巨大的。先谢谢你。

Answer 1

1. JFileChooser.getSelectedFile返回File，我不知道为什么你想将其包装在一个Comparable<File>的？文件本身实现了Comparable。
2. Scanner将接受File作为输入。尽管我对Scanner API没有经验，但我认为您不需要BufferedReader，只需创建Scanner并使用File即可，因为它的源代码应该足以让您运行。

他是一个快速测试，你可以尝试。

1. 用你需要测试的内容创建一个简单的文本文件。
2. 创建一个简单的Class，它只有一个public static void main(String args[]) {...}方法。

在main方法尝试类似...

Scanner scanner = new Scanner(new File("path/to/text/file/text.txt")); 
while (scanner.hasNext()) { 
    System.out.println(scanner.next()); 
} 

从那里开始添加在您的分析逻辑。