List of lines in a file with BufferedReader : BufferedReader « File Input Output « Java






  1. Java
  2. File Input Output
  3. BufferedReader

List of lines in a file with BufferedReader

   

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import java.io.BufferedReader;
import java.io.File;
import java.io.FileReader;
import java.io.IOException;
import java.util.ArrayList;
import java.util.List;
import java.util.Random;

public class FileList {
  public static void main(String[] args) {
    final int assumedLineLength = 50;
    File file = new File(args[0]);
    List<String> fileList = new ArrayList<String>((int) (file.length() / assumedLineLength) * 2);
    BufferedReader reader = null;
    int lineCount = 0;
    try {
      reader = new BufferedReader(new FileReader(file));
      for (String line = reader.readLine(); line != null; line = reader.readLine()) {
        fileList.add(line);
        lineCount++;
      }
    } catch (IOException e) {
      System.err.format("Could not read %s: %s%n", file, e);
      System.exit(1);
    } finally {
      if (reader != null) {
        try {
          reader.close();
        } catch (IOException e) {
        }
      }
    }
    int repeats = Integer.parseInt(args[1]);
    Random random = new Random();
    for (int i = 0; i < repeats; i++) {
      System.out.format("%d: %s%n", i, fileList.get(random.nextInt(lineCount - 1)));
    }
  }
}








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