16.5. Reading: Files

Our third option to read the contents of a text file is using the Files class of the java.nio package. To do so, we will need to create Path objects instead of File objects.

Reading all lines of a file with `Files`

We can read all lines of a file at once.

import java.io.IOException;
import java.nio.file.Files;
import java.nio.file.Path;
import java.util.List;

public class ReadAllLinesUsingFiles {
  // Reads a file, line by line, using the static method readAllLines() of the {@link Files} class.
  public static void main(String[] args) {
    Path path = Path.of("src/main/resources/names.txt");
    List<String> names = null;

    try {
      names = Files.readAllLines(path);
    } catch (IOException e) {
      e.printStackTrace();
    }

    System.out.println("Names: " + names);
  }
}

Reading an entire file with `Files`

We can read its whole content into a String.

import java.io.IOException;
import java.nio.file.Files;
import java.nio.file.Path;
import java.util.Arrays;
import java.util.List;

public class ReadEntireFileUsingFiles {
  // Reads the entire contents of a file using the static method readString() of the {@link Files} class.
  public static void main(String[] args) {
    Path path = Path.of("src/main/resources/names.txt");
    List<String> names = null;

    try {
      String fileContent = Files.readString(path);
      String[] array = fileContent.split("\n");
      names = Arrays.asList(array);
    } catch (IOException e) {
      e.printStackTrace();
    }

    System.out.println("Names: " + names);
  }
}

Using `Files` and a streams

We can even use streams.

import java.io.IOException;
import java.nio.file.Files;
import java.nio.file.Path;
import java.util.List;

public class ReadLineByLineUsingStreamFiles {

  // Reads a file_manipulation.file, line by line, using the static method lines() of the {@link Files} class.
  public static void main(String[] args) {
    Path path = Path.of("src/main/resources/names.txt");
    List<String> names = null;

    try {
      names = Files.lines(path).toList();
    } catch (IOException e) {
      e.printStackTrace();
    }

    System.out.println("Names: " + names);
  }
}

Exercise 3

Let us revisit the athlete exercise once again. This time, you should read the athletes.data file using the Files class.

After solving the exercise, reflect on the 3 ways in which you read the athletes.data file to decide which one you liked best.

16.5. Reading: Files

Reading all lines of a file with Files

Reading an entire file with Files

Using Files and a streams

Exercise 3

Reading all lines of a file with `Files`

Reading an entire file with `Files`

Using `Files` and a streams