从文件中读取并显示随机行

Question

我试图让我的 android 应用程序从文本文件中读取并随机选择一个条目然后显示它，我该怎么做呢？我想我必须使用缓冲区读取器或输入流命令，但我不知道如何使用这些，我试过谷歌搜索但没有找到太多帮助。

据我所知（在一些帮助下）我必须阅读文本文件，将其添加到字符串中？并使用以下命令随机选择一个条目

Random.nextInt(String[].length-1).

我该怎么做呢？ :\ 我对所有这些 bufferreader 等东西都很陌生。

Answer 1

您在这里询问 2 种不同的操作。不要把问题混为一谈。您想知道如何：

1. 将文件从磁盘读取到一组字符串中。

2. 从一组字符串中随机选择一个字符串。

   // Read in the file into a list of strings
   BufferedReader reader = new BufferedReader(new FileReader("inputfile.txt"));
   List<String> lines = new ArrayList<String>();
   
   String line = reader.readLine();
   
   while( line != null ) {
       lines.add(line);
       line = reader.readLine();
   }
   
   // Choose a random one from the list
   Random r = new Random();
   String randomString = lines.get(r.nextInt(lines.size()));
   

Answer 2

这里有一些从文本文件中读取的快速代码。您需要修改它以在行尾拆分，显然解决 TODO 会很好，但它应该可以帮助您开始。

try
{
    InputStream is = new FileInputStream(m_file);

    if(m_is == null)
    {
        openInputStream();
    }
    StringBuilder sb = new StringBuilder();

    //TODO: get a buffered stream going, it should be more efficient
    byte[] buf = new byte[100];
    int readLen;
    while((readLen = is.read(buf, 0, 100)) != -1)
    {
        sb.append(new String(buf, 0, readLen));
    }

    closeInputStream();
    return sb.toString();
}
catch (FileNotFoundException e)
{
    //TODO: handle this
}
finally
{
    try
    {
        is.close();
    }
    catch (IOException e)
    {
    }
}

Answer 3

/*This sample code shows how to read one term and its definition from
 the file using TextIO.
  The code just reads the term and the definition in to a String.
To read the whole file the simplest solution is to have an array
of String for the terms and an array of String for the definitions
and to ensure that you store the definition for a term at the same
index position in the definitions array as you store the term it
defines in the term array.

If you find that the TextIO window is too narrow to display the whole
of some of the lines of the definition on one line you can edit the text
file sothat each line contains fewer words (this may depend on your
screen resolution).

*/

public class Read from a txt file {


public static void main(String[]args){
    String term = "";
    String definition = ""; 
    TextIO.readFile("Your_file.txt");
    TextIO.putln("Just read this term from file: " + term);
    String str;
    do {
        str = TextIO.getln();
        definition = definition + str + "\n";
    } while (str.length() != 0);
    TextIO.putln(definition);
    // Once you have read all the file take input from keyboard:
    TextIO.readStandardInput();
}
}