Java 8 Lambdas and IO

Java8Musings/pom.xml

@@ -30,6 +30,12 @@
             <artifactId>hamcrest-core</artifactId>
             <version>1.3</version>
         </dependency>
+        <dependency>
+            <groupId>junit</groupId>
+            <artifactId>junit</artifactId>
+            <version>4.11</version>
+            <scope>test</scope>
+        </dependency>
         <dependency>
             <groupId>commons-logging</groupId>
             <artifactId>commons-logging</artifactId>

Java8Musings/src/main/java/net/briandupreez/blog/java8/io/RecursiveFileLineReader.java

@@ -0,0 +1,55 @@
+package net.briandupreez.blog.java8.io;
+
+import org.apache.commons.logging.Log;
+import org.apache.commons.logging.LogFactory;
+
+import java.io.IOException;
+import java.nio.charset.Charset;
+import java.nio.file.FileVisitOption;
+import java.nio.file.Files;
+import java.nio.file.Path;
+import java.nio.file.Paths;
+import java.util.ArrayList;
+import java.util.List;
+import java.util.stream.Stream;
+
+/**
+ * RecursiveFileLineReader
+ * Created by Brian on 2014-05-26.
+ */
+public class RecursiveFileLineReader {
+
+    private transient static final Log LOG = LogFactory.getLog(RecursiveFileLineReader.class);
+
+    /**
+     * Get all the non empty lines from all the files with the specific extension, recursively.
+     *
+     * @param path      the path to start recursion
+     * @param extension the file extension
+     * @return list of lines
+     */
+    public static List<String> readAllLineFromAllFilesRecursively(final String path, final String extension) {
+        final List<String> lines = new ArrayList<>();
+        try (final Stream<Path> pathStream = Files.walk(Paths.get(path), FileVisitOption.FOLLOW_LINKS)) {
+            pathStream
+                    .filter((p) -> !p.toFile().isDirectory() && p.toFile().getAbsolutePath().endsWith(extension))
+                    .forEach(p -> fileLinesToList(p, lines));
+        } catch (final IOException e) {
+            LOG.error(e.getMessage(), e);
+        }
+        return lines;
+    }
+
+    private static void fileLinesToList(final Path file, final List<String> lines) {
+        try (Stream<String> stream = Files.lines(file, Charset.defaultCharset())) {
+            stream
+                    .map(String::trim)
+                    .filter(s -> !s.isEmpty())
+                    .forEach(lines::add);
+        } catch (final IOException e) {
+            LOG.error(e.getMessage(), e);
+        }
+    }
+
+
+}

Java8Musings/src/test/java/net/briandupreez/blog/java8/io/RecursiveFileLineReaderTest.java

@@ -0,0 +1,16 @@
+package net.briandupreez.blog.java8.io;
+
+import org.junit.Test;
+
+import java.util.List;
+
+import static org.junit.Assert.*;
+
+public class RecursiveFileLineReaderTest {
+
+    @Test
+    public void testReadAllLineFromAllFilesRecursively() throws Exception {
+        final List<String> strings = RecursiveFileLineReader.readAllLineFromAllFilesRecursively(".", ".java");
+        assertFalse(strings.isEmpty());
+    }
+}