BAEL-36 BAEL-282 Getting file size using Java and apache commons IO api. Also grep in Java (#890)

* BAL-36 File size api in java and apache commons IO

* BAEL-36 Getting file size using Java and commons IO api.

* BAEL-282 Added support for grep functionality.

* BAEL-282 Rename the text file extension.

core-java/pom.xml

@@ -51,6 +51,18 @@
 			<artifactId>bcprov-jdk15on</artifactId>
 			<version>${bouncycastle.version}</version>
 		</dependency>
+		
+		<dependency>
+	        <groupId>org.unix4j</groupId>
+	        <artifactId>unix4j-command</artifactId>
+	        <version>0.4</version>
+	    </dependency>
+	    
+	    <dependency>
+		    <groupId>com.googlecode.grep4j</groupId> 
+		    <artifactId>grep4j</artifactId> 
+		    <version>1.8.7</version> 
+        </dependency>
 		<!-- web -->
 
 		<!-- marshalling -->

core-java/src/test/java/com/baeldung/java8/JavaFileSizeUnitTest.java

@@ -0,0 +1,65 @@
+package com.baeldung.java8;
+
+import static org.junit.Assert.assertEquals;
+
+import java.io.File;
+import java.io.IOException;
+import java.nio.channels.FileChannel;
+import java.nio.file.Path;
+import java.nio.file.Paths;
+import org.apache.commons.io.FileUtils;
+import org.junit.Before;
+import org.junit.Test;
+
+public class JavaFileSizeUnitTest {
+    private static final long EXPECTED_FILE_SIZE_IN_BYTES = 11;
+    private String filePath;
+
+    @Before
+    public void init() {
+        final String separator = File.separator;
+        filePath = String.join(separator, new String[] {"src", "test", "resources", "testFolder", "sample_file_1.in"});
+    }
+
+    @Test
+    public void whenGetFileSize_thenCorrect() {
+        final File file = new File(filePath);
+        
+        final long size = getFileSize(file);
+
+        assertEquals(EXPECTED_FILE_SIZE_IN_BYTES, size);
+    }
+
+    @Test
+    public void whenGetFileSizeUsingNioApi_thenCorrect() throws IOException {
+        final Path path = Paths.get(this.filePath);
+        final FileChannel fileChannel = FileChannel.open(path);
+        
+        final long fileSize = fileChannel.size();
+        
+        assertEquals(EXPECTED_FILE_SIZE_IN_BYTES, fileSize);
+    }
+
+    @Test
+    public void whenGetFileSizeUsingApacheCommonsIO_thenCorrect() {
+        final File file = new File(filePath);
+        
+        final long size = FileUtils.sizeOf(file);
+
+        assertEquals(EXPECTED_FILE_SIZE_IN_BYTES, size);
+    }
+
+    @Test
+    public void whenGetReadableFileSize_thenCorrect() {
+        final File file = new File(filePath);
+        
+        final long size = getFileSize(file);
+        
+        assertEquals(EXPECTED_FILE_SIZE_IN_BYTES + " bytes", FileUtils.byteCountToDisplaySize(size));
+    }
+
+    private long getFileSize(final File file) {
+        final long length = file.length();
+        return length;
+    }
+}

core-java/src/test/java/com/baeldung/java8/unix/grep/GrepWithUnix4JTest.java

@@ -0,0 +1,58 @@
+package com.baeldung.java8.unix.grep;
+
+import java.io.File;
+import java.util.List;
+
+import org.junit.Before;
+import org.junit.Test;
+import org.unix4j.Unix4j;
+import static org.unix4j.Unix4j.*;
+import static org.junit.Assert.assertEquals;
+import org.unix4j.line.Line;
+import static org.unix4j.unix.Grep.*;
+import static org.unix4j.unix.cut.CutOption.*;
+
+public class GrepWithUnix4JTest {
+	
+	private File fileToGrep;
+
+    @Before
+    public void init() {
+        final String separator = File.separator;
+        final String filePath = String.join(separator, new String[] {"src", "test", "resources", "dictionary.in"});
+        fileToGrep = new File(filePath);
+    }
+	
+	@Test
+	public void whenGrepWithSimpleString_thenCorrect() {
+	    int expectedLineCount = 4;
+	    
+	    //grep "NINETEEN" dictionary.txt 
+	    List<Line> lines = Unix4j.grep("NINETEEN", fileToGrep).toLineList();
+	    
+	    assertEquals(expectedLineCount, lines.size());
+	}
+
+	@Test
+	public void whenInverseGrepWithSimpleString_thenCorrect() {
+	    int expectedLineCount = 178687;
+	    
+	    //grep -v "NINETEEN" dictionary.txt
+	    List<Line> lines = grep(Options.v, "NINETEEN", fileToGrep).
+	                       toLineList();
+	    
+	    assertEquals(expectedLineCount, lines.size()); 
+	}
+
+
+	@Test
+	public void whenGrepWithRegex_thenCorrect() {
+	    int expectedLineCount = 151;
+	    
+	    //grep -c ".*?NINE.*?" dictionary.txt
+	    String patternCount = grep(Options.c, ".*?NINE.*?", fileToGrep).
+	                          cut(fields, ":", 1).toStringResult();
+	    
+	    assertEquals(expectedLineCount, Integer.parseInt(patternCount)); 
+	}
+}