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sreekanthsnairsreekanthsnair
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[BAEL-3121] Added source for finding number of lines in a file
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‎core-java-modules/core-java-io/src/main/java/com/baeldung/files/Main.java‎

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package com.baeldung.files;
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import static com.baeldung.files.NumberOfLineFinder.getTotalNumberOfLinesUsingApacheCommonsIO;
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import static com.baeldung.files.NumberOfLineFinder.getTotalNumberOfLinesUsingBufferedReader;
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import static com.baeldung.files.NumberOfLineFinder.getTotalNumberOfLinesUsingGoogleGuava;
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import static com.baeldung.files.NumberOfLineFinder.getTotalNumberOfLinesUsingLineNumberReader;
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import static com.baeldung.files.NumberOfLineFinder.getTotalNumberOfLinesUsingNIOFileChannel;
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import static com.baeldung.files.NumberOfLineFinder.getTotalNumberOfLinesUsingNIOFiles;
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import static com.baeldung.files.NumberOfLineFinder.getTotalNumberOfLinesUsingScanner;
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public class Main {
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private static final String INPUT_FILE_NAME = "src/main/resources/input.txt";
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public static void main(String... args) throws Exception {
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System.out.printf("Total Number of Lines Using BufferedReader: %s%n", getTotalNumberOfLinesUsingBufferedReader(INPUT_FILE_NAME));
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System.out.printf("Total Number of Lines Using LineNumberReader: %s%n", getTotalNumberOfLinesUsingLineNumberReader(INPUT_FILE_NAME));
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System.out.printf("Total Number of Lines Using Scanner: %s%n", getTotalNumberOfLinesUsingScanner(INPUT_FILE_NAME));
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System.out.printf("Total Number of Lines Using NIO Files: %s%n", getTotalNumberOfLinesUsingNIOFiles(INPUT_FILE_NAME));
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System.out.printf("Total Number of Lines Using NIO FileChannel: %s%n", getTotalNumberOfLinesUsingNIOFileChannel(INPUT_FILE_NAME));
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System.out.printf("Total Number of Lines Using Apache Commons IO: %s%n", getTotalNumberOfLinesUsingApacheCommonsIO(INPUT_FILE_NAME));
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System.out.printf("Total Number of Lines Using NIO Google Guava: %s%n", getTotalNumberOfLinesUsingGoogleGuava(INPUT_FILE_NAME));
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}
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}

‎core-java-modules/core-java-io/src/main/java/com/baeldung/files/NumberOfLineFinder.java‎

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package com.baeldung.files;
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import java.io.BufferedReader;
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import java.io.File;
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import java.io.FileReader;
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import java.io.IOException;
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import java.io.LineNumberReader;
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import java.nio.ByteBuffer;
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import java.nio.channels.FileChannel;
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import java.nio.channels.FileChannel.MapMode;
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import java.nio.charset.Charset;
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import java.nio.file.Files;
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import java.nio.file.Paths;
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import java.nio.file.StandardOpenOption;
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import java.util.List;
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import java.util.Scanner;
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import java.util.stream.Stream;
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import org.apache.commons.io.FileUtils;
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import org.apache.commons.io.LineIterator;
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public class NumberOfLineFinder {
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public static int getTotalNumberOfLinesUsingBufferedReader(String fileName) {
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int lines = 0;
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try (BufferedReader reader = new BufferedReader(new FileReader(fileName))) {
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while (reader.readLine() != null) {
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lines++;
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}
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} catch (IOException ioe) {
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ioe.printStackTrace();
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}
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return lines;
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}
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public static int getTotalNumberOfLinesUsingLineNumberReader(String fileName) {
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int lines = 0;
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try (LineNumberReader reader = new LineNumberReader(new FileReader(fileName))) {
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reader.skip(Integer.MAX_VALUE);
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lines = reader.getLineNumber() + 1;
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} catch (IOException ioe) {
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ioe.printStackTrace();
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}
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return lines;
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}
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public static int getTotalNumberOfLinesUsingScanner(String fileName) {
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int lines = 0;
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try (Scanner scanner = new Scanner(new FileReader(fileName))) {
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while (scanner.hasNextLine()) {
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scanner.nextLine();
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lines++;
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}
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} catch (IOException ioe) {
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ioe.printStackTrace();
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}
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return lines;
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}
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public static int getTotalNumberOfLinesUsingNIOFiles(String fileName) {
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int lines = 0;
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try (Stream<String> fileStream = Files.lines(Paths.get(fileName))) {
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lines = (int) fileStream.count();
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} catch (IOException ioe) {
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ioe.printStackTrace();
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}
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return lines;
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}
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public static int getTotalNumberOfLinesUsingNIOFileChannel(String fileName) {
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int lines = 1;
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try (FileChannel channel = FileChannel.open(Paths.get(fileName), StandardOpenOption.READ)) {
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ByteBuffer byteBuffer = channel.map(MapMode.READ_ONLY, 0, channel.size());
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while (byteBuffer.hasRemaining()) {
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byte currentChar = byteBuffer.get();
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if (currentChar == '\n') {
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lines++;
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}
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}
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} catch (IOException ioe) {
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ioe.printStackTrace();
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}
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return lines;
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}
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public static int getTotalNumberOfLinesUsingApacheCommonsIO(String fileName) {
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int lines = 0;
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try {
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LineIterator lineIterator = FileUtils.lineIterator(new File(fileName));
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while (lineIterator.hasNext()) {
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lineIterator.nextLine();
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lines++;
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}
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} catch (IOException ioe) {
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ioe.printStackTrace();
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}
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return lines;
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}
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public static int getTotalNumberOfLinesUsingGoogleGuava(String fileName) {
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int lines = 0;
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try {
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List<String> lineItems = com.google.common.io.Files.readLines(Paths.get(fileName)
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.toFile(), Charset.defaultCharset());
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lines = lineItems.size();
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} catch (IOException ioe) {
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ioe.printStackTrace();
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}
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return lines;
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}
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}

‎core-java-modules/core-java-io/src/test/java/com/baeldung/file/NumberOfLineFinderUnitTest.java‎

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package com.baeldung.file;
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import static com.baeldung.files.NumberOfLineFinder.getTotalNumberOfLinesUsingApacheCommonsIO;
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import static com.baeldung.files.NumberOfLineFinder.getTotalNumberOfLinesUsingBufferedReader;
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import static com.baeldung.files.NumberOfLineFinder.getTotalNumberOfLinesUsingGoogleGuava;
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import static com.baeldung.files.NumberOfLineFinder.getTotalNumberOfLinesUsingLineNumberReader;
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import static com.baeldung.files.NumberOfLineFinder.getTotalNumberOfLinesUsingNIOFileChannel;
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import static com.baeldung.files.NumberOfLineFinder.getTotalNumberOfLinesUsingNIOFiles;
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import static com.baeldung.files.NumberOfLineFinder.getTotalNumberOfLinesUsingScanner;
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import static org.junit.Assert.assertEquals;
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import org.junit.Test;
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public class NumberOfLineFinderUnitTest {
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private static final String INPUT_FILE_NAME = "src/main/resources/input.txt";
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private static final int ACTUAL_LINE_COUNT = 45;
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@Test
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public void whenUsingBufferedReader_thenReturnTotalNumberOfLines() {
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int lines = getTotalNumberOfLinesUsingBufferedReader(INPUT_FILE_NAME);
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assertEquals(ACTUAL_LINE_COUNT, lines);
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}
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@Test
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public void whenUsingLineNumberReader_thenReturnTotalNumberOfLines() {
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int lines = getTotalNumberOfLinesUsingLineNumberReader(INPUT_FILE_NAME);
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assertEquals(ACTUAL_LINE_COUNT, lines);
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}
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@Test
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public void whenUsingScanner_thenReturnTotalNumberOfLines() {
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int lines = getTotalNumberOfLinesUsingScanner(INPUT_FILE_NAME);
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assertEquals(ACTUAL_LINE_COUNT, lines);
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}
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@Test
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public void whenUsingNIOFiles_thenReturnTotalNumberOfLines() {
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int lines = getTotalNumberOfLinesUsingNIOFiles(INPUT_FILE_NAME);
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assertEquals(ACTUAL_LINE_COUNT, lines);
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}
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@Test
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public void whenUsingNIOFileChannel_thenReturnTotalNumberOfLines() {
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int lines = getTotalNumberOfLinesUsingNIOFileChannel(INPUT_FILE_NAME);
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assertEquals(ACTUAL_LINE_COUNT, lines);
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}
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@Test
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public void whenUsingApacheCommonsIO_thenReturnTotalNumberOfLines() {
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int lines = getTotalNumberOfLinesUsingApacheCommonsIO(INPUT_FILE_NAME);
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assertEquals(ACTUAL_LINE_COUNT, lines);
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}
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@Test
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public void whenUsingGoogleGuava_thenReturnTotalNumberOfLines() {
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int lines = getTotalNumberOfLinesUsingGoogleGuava(INPUT_FILE_NAME);
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assertEquals(ACTUAL_LINE_COUNT, lines);
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}
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}

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