从 java 中的文本文件中搜索多个字符串

Question

I'm trying to search of multiple words given from a user ( i used array to store them in ) from one txt file, and then if that word presented once in the file it will be displayed and if it's not it won't. also for the words itself, if it's duplicated it will search it once.

the problem now when i search for only one it worked, but with multiple words it keeps repeated that the word isn't present even if it's there.

i would like to know where should i put the for loop and what's the possible changes.

package search;
import java.io.*;
import java.util.Scanner;

public class Read {
    public static void main(String[] args) throws IOException 
       {
        Scanner sc = new Scanner(System.in);
        
          String[] words=null;  
          FileReader fr = new FileReader("java.txt");  
          BufferedReader br = new BufferedReader(fr);
          
          String s;     
          
          System.out.println("Enter the number of words:");
          Integer n = sc.nextInt();
          
          String wordsArray[] = new String[n];
          System.out.println("Enter words:");
          for(int i=0; i<n; i++)  
          {
              wordsArray[i]=sc.next();  
          }

           
         for (int i = 0; i <n; i++) {
             int count=0;   //Intialize the word to zero
              while((s=br.readLine())!=null)   //Reading Content from the file
          {
            {
             words=s.split(" ");  //Split the word using space
             
              for (String word : words) 
              {
                     if (word.equals(wordsArray[i]))   //Search for the given word
                     {
                       count++;    //If Present increase the count by one
                     }
              }
              
          if(count == 1)
          {
             System.out.println(wordsArray[i] + " is unique in file ");
          }
          else if (count == 0)
          {
             System.out.println("The given word is not present in the file");
          }
          else
          {
             System.out.println("The given word is present in the file more than 1 time");
          }
          }
            }
             }
             fr.close();
       }
    }

Answer 1

The code which you wrote is error prone and remember always there should be proper break condition when you use while loop.

Try the following code:

 public class Read {
  
  public static void main(String[] args)
  {

    // Declaring the String
    String paragraph = "These words can be searched";
    // Declaring a HashMap of <String, Integer>
    Map<String, Integer> hashMap = new HashMap<>();

    // Splitting the words of string
    // and storing them in the array.
    String[] words = new String[]{"These", "can", "searched"};

    for (String word : words) {

      // Asking whether the HashMap contains the
      // key or not. Will return null if not.
      Integer integer = hashMap.get(word);

      if (integer == null)
        // Storing the word as key and its
        // occurrence as value in the HashMap.
        hashMap.put(word, 1);

      else {
        // Incrementing the value if the word
        // is already present in the HashMap.
        hashMap.put(word, integer + 1);
      }
    }
    System.out.println(hashMap);
  }
}

I've tried by hard coding the values, you can take words and paragraph from the file and console.

Answer 2

The 'proper' class to use for extracting words from text is java.text.BreakIterator

You can try the following (reading line-wise in case of large files)

import java.text.BreakIterator;
import java.util.Arrays;
import java.util.ArrayList;
import java.util.List;
import java.util.stream.Stream;
import java.nio.file.Files;
import java.nio.file.Paths;

public class WordFinder {

    public static void main(String[] args) {
        try {
            if (args.length < 2) {
                WordFinder.usage();
                System.exit(1);
            }
            ArrayList<String> argv = new ArrayList<>(Arrays.asList(args));
            String path = argv.remove(0);
            List<String> found = WordFinder.findWords(Files.lines(Paths.get(path)), argv);
            System.out.printf("Found the following word(s) in file at %s%n", path);
            System.out.println(found);
        } catch (Throwable t) {
            t.printStackTrace();
        }
    }

    public static List<String> findWords(Stream<String> lines, ArrayList<String> searchWords) {
        List<String> result = new ArrayList<>();
        BreakIterator boundary = BreakIterator.getWordInstance();
        lines.forEach(line -> {
            boundary.setText(line);

            int start = boundary.first();
            for (int end = boundary.next(); end != BreakIterator.DONE; start = end, end = boundary.next()) {
                String candidate = line.substring(start, end);
                if (searchWords.contains(candidate)) {
                    result.add(candidate);
                    searchWords.remove(candidate);
                }
            }
        });
        return result;
    }

    private static void usage() {
        System.err.println("Usage: java WordFinder <Path to input file> <Word 1> [<Word 2> <Word 3>...]");
    }
}

Sample run:

goose@t410:/tmp$ echo 'the quick brown fox jumps over the lazy dog' >quick.txt
goose@t410:/tmp$ java WordFinder quick.txt dog goose the did quick over
Found the following word(s) in file at quick.txt
[the, quick, over, dog]
goose@t410:/tmp$