Modern Java

The Battle of Thermopylae was fought between an alliance of
Greek city-states, led by King Leonidas of Sparta, and the Persian Empire of
Xerxes I over the course of three days, during the second Persian invasion of
Greece. 

The thermopylae.txt file.

FileReader

Always explicitly specify the encoding for FileReader. Fixed in Java 11.
In previous versions, FileReader used platform defined encoding which is
error-prone.

import java.io.BufferedReader;
import java.io.FileReader;
import java.io.IOException;
import java.nio.charset.StandardCharsets;

void main() throws IOException {

    var fileName = "thermopylae.txt";

    try (var br = new BufferedReader(new FileReader(fileName,
            StandardCharsets.UTF_8))) {

        String line;
        while ((line = br.readLine()) != null) {

            System.out.println(line);
        }
    }
}