diff --git a/core-java/src/test/java/org/baeldung/java/io/JavaFolderSizeTest.java b/core-java/src/test/java/org/baeldung/java/io/JavaFolderSizeTest.java
new file mode 100644
index 0000000000..a0c9c13692
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+++ b/core-java/src/test/java/org/baeldung/java/io/JavaFolderSizeTest.java
@@ -0,0 +1,110 @@
+package org.baeldung.java.io;
+
+import static org.junit.Assert.assertEquals;
+
+import java.io.File;
+import java.io.IOException;
+import java.nio.file.FileVisitResult;
+import java.nio.file.Files;
+//import java.nio.file.Files;
+import java.nio.file.Path;
+import java.nio.file.Paths;
+import java.nio.file.SimpleFileVisitor;
+import java.nio.file.attribute.BasicFileAttributes;
+import java.text.DecimalFormat;
+import java.util.concurrent.atomic.AtomicLong;
+import java.util.stream.StreamSupport;
+
+import org.apache.commons.io.FileUtils;
+import org.junit.Test;
+
+public class JavaFolderSizeTest {
+
+    @Test
+    public void whenGetFolderSizeRecursive_thenCorrect() {
+        final long expectedSize = 12607;
+
+        final File folder = new File("src/test/resources");
+        final long size = getFolderSize(folder);
+
+        assertEquals(expectedSize, size);
+    }
+
+    @Test
+    public void whenGetFolderSizeUsingJava7_thenCorrect() throws IOException {
+        final long expectedSize = 12607;
+
+        final AtomicLong size = new AtomicLong(0);
+        final Path folder = Paths.get("src/test/resources");
+
+        Files.walkFileTree(folder, new SimpleFileVisitor<Path>() {
+            @Override
+            public FileVisitResult visitFile(final Path file, final BasicFileAttributes attrs) throws IOException {
+                size.addAndGet(attrs.size());
+                return FileVisitResult.CONTINUE;
+            }
+        });
+
+        assertEquals(expectedSize, size.longValue());
+    }
+
+    @Test
+    public void whenGetFolderSizeUsingJava8_thenCorrect() throws IOException {
+        final long expectedSize = 12607;
+
+        final Path folder = Paths.get("src/test/resources");
+        final long size = Files.walk(folder).filter(p -> p.toFile().isFile()).mapToLong(p -> p.toFile().length()).sum();
+
+        assertEquals(expectedSize, size);
+    }
+
+    @Test
+    public void whenGetFolderSizeUsingApacheCommonsIO_thenCorrect() {
+        final long expectedSize = 12607;
+
+        final File folder = new File("src/test/resources");
+        final long size = FileUtils.sizeOfDirectory(folder);
+
+        assertEquals(expectedSize, size);
+    }
+
+    @Test
+    public void whenGetFolderSizeUsingGuava_thenCorrect() {
+        final long expectedSize = 12607;
+
+        final File folder = new File("src/test/resources");
+
+        final Iterable<File> files = com.google.common.io.Files.fileTreeTraverser().breadthFirstTraversal(folder);
+        final long size = StreamSupport.stream(files.spliterator(), false).filter(f -> f.isFile()).mapToLong(File::length).sum();
+
+        assertEquals(expectedSize, size);
+    }
+
+    @Test
+    public void whenGetReadableSize_thenCorrect() {
+        final File folder = new File("src/test/resources");
+        final long size = getFolderSize(folder);
+
+        final String[] units = new String[] { "B", "KB", "MB", "GB", "TB" };
+        final int unitIndex = (int) (Math.log10(size) / 3);
+        final double unitValue = 1 << (unitIndex * 10);
+
+        final String readableSize = new DecimalFormat("#,##0.#").format(size / unitValue) + " " + units[unitIndex];
+        assertEquals("12.3 KB", readableSize);
+    }
+
+    private long getFolderSize(final File folder) {
+        long length = 0;
+        final File[] files = folder.listFiles();
+
+        final int count = files.length;
+
+        for (int i = 0; i < count; i++) {
+            if (files[i].isFile())
+                length += files[i].length();
+            else
+                length += getFolderSize(files[i]);
+        }
+        return length;
+    }
+}
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