从.txt文件读取和存储数据到数组的问题

Program:

User enters a file name containing numbers (1 per line)

用户输入包含数字的文件名(每行1个)

File is read and data is stored in StringBuffer

读取文件并将数据存储在StringBuffer中

StringBuffer is converted to String type

StringBuffer转换为String类型

String is split() and stored in a String[]

字符串是split()并存储在String []中

Double[] is created and converts/stores elements of the String[]

创建Double []并转换/存储String []的元素

The above is what I am trying to achieve; however, the program is not working. *Look below for an example...

以上就是我想要实现的目标;但是,该程序无法正常工作。 *请看下面的例子......

class tester
{
public static int x = 0;
public static double[] dataArray = new double[x];//array storing elements

public static void main(String[] args) throws IOException
{
    //userInput .txt
    Scanner sc = new Scanner(System.in);
    System.out.println("Enter filename:\n");
    String name = sc.nextLine();

    File file = new File(name);
    FileReader fileReader = new FileReader(file);
    BufferedReader bufferedReader = new BufferedReader(fileReader);
    StringBuffer stringBuffer = new StringBuffer();
    String newString = stringBuffer.toString();

    String [] stringArray = newString.split("\n");
    double [] dataArray = new double[stringArray.length];

    for(int i=0 ; i < stringArray.length ; i++)
    {  
        dataArray[i] = Double.parseDouble(stringArray[i]);  
    }

I have a file named: Ben.txt that looks like this:

我有一个名为:Ben.txt的文件,如下所示:

When I run the program...

当我运行程序时......

Enter filename:

c:/Ben.txt
Exception in thread "main" java.lang.NumberFormatException: empty String
at sun.misc.FloatingDecimal.readJavaFormatString(Unknown Source)
at sun.misc.FloatingDecimal.parseDouble(Unknown Source)
at java.lang.Double.parseDouble(Unknown Source)
at tester.main(tester.java:27)

2 个解决方案

#1

The problem is you are not actually reading anything from the file. You do all the setup but you aren't reading.

问题是你实际上没有从文件中读取任何内容。你做了所有的设置,但你没有阅读。

So when you have:

所以当你有:

    File file = new File(name);
    FileReader fileReader = new FileReader(file);
    BufferedReader bufferedReader = new BufferedReader(fileReader);
    StringBuffer stringBuffer = new StringBuffer();
    String newString = stringBuffer.toString();

Here I don't think you actually need a StringBuffer, all you have to add/replace is this

在这里我不认为你真的需要一个StringBuffer,所有你必须添加/替换就是这个

    String str;
    str = bufferedReader.readLine();

If you want to read the whole file all you have to do is iterate over the entire file using readLine().

如果要读取整个文件,您只需使用readLine()遍历整个文件即可。

#2

As GiantTree said, you are not actually reading in the file at all

正如GiantTree所说,你实际上并没有阅读文件

Changing the definition of newString to the following will give you some progress.

将newString的定义更改为以下内容将为您提供一些进展。

  String newString = bufferedReader.readLine();

Other things you should consider:

您应该考虑的其他事项:

closing the resources you've opened

关闭你打开的资源

exception handling
following standard class naming conventions

遵循标准类命名约定

no need to initialise dataArray twice

无需初始化dataArray两次

#1