BufferedReader指针 [英] BufferedReader pointer

问题描述

我有以下代码，但我不明白如何将指针重置为起始位置：

I have the following code but I don't understand how I can reset the pointer to the starter position:

BufferedReader inp=new BufferedReader(new FileReader(file));
Scanner leggi=new Scanner(inp);
for(int i=0;i<nwords;i++){
  while(leggi.hasNext()) 
    if(leggi.next().equals(args[i+2])) 
      occorrenze[i]=occorrenze[i]+1;
}
inp.close();

我尝试过

inp.mark(0);
inp.reset();

没有结果。

推荐答案

Paul，

我建议您通读以下旧主题： Java BufferedReader返回文本文件的顶部吗？。

I suggest you read through this old thread: Java BufferedReader back to the top of a text file?.

我个人更喜欢Jon Skeet的回答，归结为不要麻烦[除非您必须]。

Personally I prefer Jon Skeet's response, which boils down to "Don't bother [unless you MUST]."

干杯。基思。

编辑：另外，即使您点击了，也应该始终关闭该输入文件异常。 最终块对此非常合适。

Also you should ALLWAYS close that input file, even if you hit an Exception. The finally block is perfect for this.

EDIT2：

希望您仍然与我们在一起。

Hope you're still with us.

这是我的尝试，FWIW ，则无需重置输入文件，只需为循环转置 while 和。

Here's my attempt, and FWIW, you DON'T need to reset the input-file, you just need to transpose your while and for loops.

package forums;

import java.util.Scanner;
import java.io.BufferedReader;
import java.io.FileReader;
import java.io.IOException;

public class WordOccurrenceCount
{
  public static void main(String[] args) {
    try {
      String[] words = { "and", "is", "a", "the", "of", "as" };
      int[] occurrences = readOccurrences("C:/tmp/prose.txt", words);
      for ( int i=0; i<words.length; i++ ) {
        System.out.println(words[i] + " " + occurrences[i]);
      }
    } catch (Exception e) {
      e.printStackTrace();
    }
  }

  private static final int[] readOccurrences(String filename, String... words) 
    throws IOException
  {
    int[] occurrences = new int[words.length];
    BufferedReader reader = null;
    try {
      reader = new BufferedReader(new FileReader(filename));
      Scanner scanner = new Scanner(reader);
      while ( scanner.hasNext() ) {
        String word = scanner.next();
        for ( int i=0; i<words.length; i++ ) {
          if ( words[i].equals(word) ) {
            occurrences[i]++;
          }
        }
      }
    } finally {
      if(reader!=null) reader.close();
    }
    return occurrences;
  }
}

和 BTW ， java.util.Map 非常适合构建频率表... 并行数组仅仅是90年代。 Map的默认实现是 HashMap 类...默认情况下，我的意思是在需要Map时使用HashMap，除非您有充分的理由使用某些东西否则，这种情况不会经常发生。 HashMap通常是表现最好的全能工具。

And BTW, java.util.Map is perfect for building a frequency table... Parallel arrays are just SOOOOO 90's. The "default" implementation of Map is the HashMap class... By default I mean use HashMap whenever you need a Map, unless you've got a good reason to use something else, which won't be often. HashMap is generally the best allround performer.

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