从文本文件中解析数字 [英] parsing numbers from a text file

问题描述

只是想知道我在这里做错了什么。我正在尝试从文件中读取并通过一些数据进行解析。我不断收到错误java.lang.NumberFormatException，它不能解析数字。我知道我使用getNextDouble（）或得到nextInt（），但即时通讯尽量保持代码一般，因为我可以。任何想法将不胜感激。 ty。

下面是我的文本文件中的一行样本：

  foo Bar 19.35 55 987.0054 4 
 
 public void readFile（）{
 int i = 0; 
字符串行; 
 
尝试{
 fileIn = new Scanner（new File（pa1Names.txt））; 
 catch（Exception e）{
 System.out.println（致命错误：文件未打开）; （$< name.length&& fileIn.hasNext（））{
 line = fileIn.nextLine（）; 
} 
 
。 
 StringTokenizer st = new StringTokenizer（line）; 
 int m = st.countTokens（）; 
 
 names [i] = st.nextToken（）; （int k = 0; k  {b 
名字[i] = names [i] ++ st.nextToken（） ; 
} 
 
 reals [i] [0] = Double.parseDouble（st.nextToken（））; 
 ints [i] [0] = Integer.parseInt（st.nextToken（））; 
 reals [i] [1] = Double.parseDouble（st.nextToken（））; 
 ints [i] [1] = Integer.parseInt（st.nextToken（））; 
 
 i ++; 
} // end while 
 fileIn.close（）; 
 
  

解决方案

，您需要在catch块中放入一个return语句，或者您需要将其余的代码移动到try块内部（如果文件打开失败，即使您发现错误，fileIn.HasNext也会一定因为该文件仍然没有打开）。

我也复制并粘贴了你的代码，并通过调试器运行它，我认为你的第一个for循环是关闭的，作为名称[i]是：

foo// names [i] = st.nextToken（）;

foo bar//名字的第一次迭代[i] = names [i] ++ st.nextToken（）;

foo Bar 19.35 //第二次迭代的名字[i] = names [i] ++ st.nextToken（）;

reals [i] [0]在整数（55）中，值为55.0
然后ints [i] [0]抛出一个异常，因为下一个数字是一个double，而不是一个int。

所以你的for循环应该是：

  for（int k = 0; K< M-5; k）
 {
 name = name ++ st.nextToken（）; 
} 
  

just wondering what i am doing wrong here. i am trying to read from a file and parse through some data. i keep getting error "java.lang.NumberFormatException" that it can't parse the numbers. I know i use getNextDouble() or get nextInt() but im trying to keep the code as general as i can. Any thoughts would be greatly appreciated. ty.

here is a sample of a line from my text file:

       foo Bar 19.35 55 987.0054 4 

public void readFile(){
        int i=0;
        String line;

        try{
            fileIn = new Scanner(new File("pa1Names.txt"));
        }catch(Exception e){
            System.out.println("Fatal Error: File was not opened");
        }

        while(i<names.length && fileIn.hasNext()){
            line = fileIn.nextLine();
            StringTokenizer st = new StringTokenizer(line);
            int m = st.countTokens();

            names[i] = st.nextToken();

            for (int k = 0; k<m-5; k++)
            {
                names[i] = names[i] + " " + st.nextToken();
            }

            reals[i][0] = Double.parseDouble(st.nextToken());
            ints[i][0]  = Integer.parseInt(st.nextToken());
            reals[i][1] = Double.parseDouble(st.nextToken());
            ints[i][1]  = Integer.parseInt(st.nextToken());

            i++;
        }//end while
        fileIn.close();
    }

解决方案

In your try/catch block, you need to put in a return statement in the catch block, or you need to move the rest of the code to be inside the try block (if the file open fails, even though you caught the error, the fileIn.HasNext will definitely fail because the file is still not open).

I also copied and pasted your code and ran it through a debugger, I think your first for loop is off, as names[i] is the following:

"foo" //names[i] = st.nextToken();

"foo bar" // first iteration of names[i] = names[i] + " " + st.nextToken();

"foo Bar 19.35" // second iteration of names[i] = names[i] + " " + st.nextToken();

The reals[i][0] then reads in the integer (55), so has a value of 55.0 The ints[i][0] is then throwing an exception because the next number is a double not an int.

So your for loop should be:

            for (int k = 0; k<m-5; k++)
            {
                name = name+ " " + st.nextToken();
            }

这篇关于从文本文件中解析数字的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！