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Merge pull request #7450 from sreekanthsnair/master 

[BAEL-3121] Added source for finding number of lines in a file
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Erik Pragt 2019-07-31 21:17:29 +10:00 committed by GitHub
parent e11d555977 2aa2f078dd
commit 4e31224703
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24
core-java-modules/core-java-io/src/main/java/com/baeldung/files/Main.java Normal file
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package com.baeldung.files;
import static com.baeldung.files.NumberOfLineFinder.getTotalNumberOfLinesUsingApacheCommonsIO;
import static com.baeldung.files.NumberOfLineFinder.getTotalNumberOfLinesUsingBufferedReader;
import static com.baeldung.files.NumberOfLineFinder.getTotalNumberOfLinesUsingGoogleGuava;
import static com.baeldung.files.NumberOfLineFinder.getTotalNumberOfLinesUsingLineNumberReader;
import static com.baeldung.files.NumberOfLineFinder.getTotalNumberOfLinesUsingNIOFileChannel;
import static com.baeldung.files.NumberOfLineFinder.getTotalNumberOfLinesUsingNIOFiles;
import static com.baeldung.files.NumberOfLineFinder.getTotalNumberOfLinesUsingScanner;
public class Main {
private static final String INPUT_FILE_NAME = "src/main/resources/input.txt";
public static void main(String... args) throws Exception {
System.out.printf("Total Number of Lines Using BufferedReader: %s%n", getTotalNumberOfLinesUsingBufferedReader(INPUT_FILE_NAME));
System.out.printf("Total Number of Lines Using LineNumberReader: %s%n", getTotalNumberOfLinesUsingLineNumberReader(INPUT_FILE_NAME));
System.out.printf("Total Number of Lines Using Scanner: %s%n", getTotalNumberOfLinesUsingScanner(INPUT_FILE_NAME));
System.out.printf("Total Number of Lines Using NIO Files: %s%n", getTotalNumberOfLinesUsingNIOFiles(INPUT_FILE_NAME));
System.out.printf("Total Number of Lines Using NIO FileChannel: %s%n", getTotalNumberOfLinesUsingNIOFileChannel(INPUT_FILE_NAME));
System.out.printf("Total Number of Lines Using Apache Commons IO: %s%n", getTotalNumberOfLinesUsingApacheCommonsIO(INPUT_FILE_NAME));
System.out.printf("Total Number of Lines Using NIO Google Guava: %s%n", getTotalNumberOfLinesUsingGoogleGuava(INPUT_FILE_NAME));
}
}

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

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