diff --git a/core-java-modules/core-java-io-4/.gitignore b/core-java-modules/core-java-io-4/.gitignore
new file mode 100644
index 0000000000..0c0cd871c5
--- /dev/null
+++ b/core-java-modules/core-java-io-4/.gitignore
@@ -0,0 +1,2 @@
+test-link*
+0.*
\ No newline at end of file
diff --git a/core-java-modules/core-java-io-4/README.md b/core-java-modules/core-java-io-4/README.md
new file mode 100644
index 0000000000..7cc38bb9fe
--- /dev/null
+++ b/core-java-modules/core-java-io-4/README.md
@@ -0,0 +1,8 @@
+## Core Java IO
+
+This module contains articles about core Java input and output (IO)
+
+### Relevant Articles: 
+
+- [Java File Separator vs File Path Separator]
+- [[<-- Prev]](/core-java-modules/core-java-io-3)
diff --git a/core-java-modules/core-java-io-4/pom.xml b/core-java-modules/core-java-io-4/pom.xml
new file mode 100644
index 0000000000..ee31b35ba9
--- /dev/null
+++ b/core-java-modules/core-java-io-4/pom.xml
@@ -0,0 +1,52 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<project
+    xmlns="http://maven.apache.org/POM/4.0.0"
+    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+    xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
+    <modelVersion>4.0.0</modelVersion>
+    <artifactId>core-java-io-4</artifactId>
+    <version>0.1.0-SNAPSHOT</version>
+    <name>core-java-io-4</name>
+    <packaging>jar</packaging>
+    <parent>
+        <groupId>com.baeldung.core-java-modules</groupId>
+        <artifactId>core-java-modules</artifactId>
+        <version>0.0.1-SNAPSHOT</version>
+        <relativePath>../</relativePath>
+    </parent>
+
+    <dependencies>
+        <!-- utils -->
+        <dependency>
+            <groupId>commons-io</groupId>
+            <artifactId>commons-io</artifactId>
+            <version>${commons-io.version}</version>
+        </dependency>
+        <!-- logging -->
+        <dependency>
+            <groupId>log4j</groupId>
+            <artifactId>log4j</artifactId>
+            <version>${log4j.version}</version>
+        </dependency>
+        <dependency> <!-- needed to bridge to slf4j for projects that use the log4j APIs directly -->
+            <groupId>org.slf4j</groupId>
+            <artifactId>log4j-over-slf4j</artifactId>
+            <version>${org.slf4j.version}</version>
+        </dependency>
+        <!-- test scoped -->
+        <dependency>
+            <groupId>org.assertj</groupId>
+            <artifactId>assertj-core</artifactId>
+            <version>${assertj.version}</version>
+            <scope>test</scope>
+        </dependency>
+    </dependencies>
+
+    <build>
+    </build>
+
+    <properties>
+        <assertj.version>3.6.1</assertj.version>
+    </properties>
+
+</project>
\ No newline at end of file
diff --git a/core-java-modules/core-java-io-4/src/test/java/com/baeldung/fileseparator/FilePathSeparatorUnitTest.java b/core-java-modules/core-java-io-4/src/test/java/com/baeldung/fileseparator/FilePathSeparatorUnitTest.java
new file mode 100644
index 0000000000..959aae8aff
--- /dev/null
+++ b/core-java-modules/core-java-io-4/src/test/java/com/baeldung/fileseparator/FilePathSeparatorUnitTest.java
@@ -0,0 +1,63 @@
+package com.baeldung.fileseparator;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+
+import java.io.File;
+import java.io.IOException;
+import java.util.StringJoiner;
+
+import org.junit.jupiter.api.Test;
+import org.junit.jupiter.api.condition.EnabledOnOs;
+import org.junit.jupiter.api.condition.OS;
+
+public class FilePathSeparatorUnitTest {
+
+    @Test
+    @EnabledOnOs(OS.WINDOWS)
+    public void whenCheckPathSeparator_thenResultIsAsExpectedOnWindows() throws IOException {
+        assertEquals(";", File.pathSeparator);
+        assertEquals(';', File.pathSeparatorChar);
+    }
+    
+    @Test
+    @EnabledOnOs({ OS.LINUX, OS.MAC })
+    public void whenCheckPathSeparator_thenResultIsAsExpected() throws IOException {
+        assertEquals(":", File.pathSeparator);
+        assertEquals(':', File.pathSeparatorChar);
+    }
+    
+    @Test
+    @EnabledOnOs(OS.WINDOWS)
+    public void whenBuildPathUsingString_thenResultIsAsExpectedOnWindows() throws IOException {
+        String[] pathNames = { "path1", "path2", "path3" };
+        String path = String.join(File.pathSeparator, pathNames);
+        assertEquals("path1;path2;path3",path);
+    }
+
+    @Test
+    @EnabledOnOs({ OS.LINUX, OS.MAC })
+    public void whenBuildPathUsingString_thenResultIsAsExpected() throws IOException {
+        String[] pathNames = { "path1", "path2", "path3" };
+        String path = String.join(File.pathSeparator, pathNames);
+        assertEquals("path1:path2:path3", path);
+    }
+
+    @Test
+    @EnabledOnOs(OS.WINDOWS)
+    public void whenbuildPathUsingStringJoiner_thenResultIsAsExpectedOnWindows() throws IOException {
+        assertEquals("path1;path2", buildPathUsingStringJoiner("path1", "path2"));
+    }
+
+    @Test
+    @EnabledOnOs({ OS.LINUX, OS.MAC })
+    public void whenbuildPathUsingStringJoiner_thenResultIsAsExpected() throws IOException {
+        assertEquals("path1:path2", buildPathUsingStringJoiner("path1", "path2"));
+    }
+    
+    private String buildPathUsingStringJoiner(String path1, String path2) {
+        StringJoiner joiner = new StringJoiner(File.pathSeparator);
+        joiner.add(path1);
+        joiner.add(path2);
+        return joiner.toString();
+    }
+}
\ No newline at end of file
diff --git a/core-java-modules/core-java-io-4/src/test/java/com/baeldung/fileseparator/FileSeparatorUnitTest.java b/core-java-modules/core-java-io-4/src/test/java/com/baeldung/fileseparator/FileSeparatorUnitTest.java
new file mode 100644
index 0000000000..f908dcc9bb
--- /dev/null
+++ b/core-java-modules/core-java-io-4/src/test/java/com/baeldung/fileseparator/FileSeparatorUnitTest.java
@@ -0,0 +1,63 @@
+package com.baeldung.fileseparator;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+
+import java.io.File;
+import java.nio.file.FileSystems;
+import java.nio.file.Path;
+import java.nio.file.Paths;
+
+import org.junit.jupiter.api.Test;
+import org.junit.jupiter.api.condition.EnabledOnOs;
+import org.junit.jupiter.api.condition.OS;
+
+public class FileSeparatorUnitTest {
+
+    @Test
+    @EnabledOnOs(OS.WINDOWS)
+    public void whenCheckFileSeparator_thenCorrectOnWindows() {
+        assertEquals("\\", File.separator);
+        assertEquals('\\', File.separatorChar);
+        
+        String fileSeparator = FileSystems.getDefault().getSeparator();
+        assertEquals("\\",fileSeparator);
+    }
+    
+    @Test
+    @EnabledOnOs({ OS.LINUX, OS.MAC })
+    public void whenCheckFileSeparator_thenCorrect() {
+        assertEquals("/", File.separator);
+        assertEquals('/', File.separatorChar);
+        
+        String fileSeparator = FileSystems.getDefault().getSeparator();
+        assertEquals("/",fileSeparator);
+    }
+    
+    @Test
+    @EnabledOnOs(OS.WINDOWS)
+    public void whenBuildFilePathUsingPathsClass_thenCorrectOnWindows() {
+        Path path = Paths.get("dir1", "dir2");
+        assertEquals("dir1\\dir2", path.toString());
+    }
+
+    @Test
+    @EnabledOnOs({ OS.LINUX, OS.MAC })
+    public void whenBuildFilePathUsingPathsClass_thenCorrect() {
+        Path path = Paths.get("dir1", "dir2");
+        assertEquals("dir1/dir2", path.toString());
+    }
+
+    @Test
+    @EnabledOnOs(OS.WINDOWS)
+    public void whenBuildFilePathUsingFileClass_thenOutputIsAsExpectedOnWindows() {
+        File file = new File("file1", "file2");
+        assertEquals("file1\\file2", file.toString());
+    }
+
+    @Test
+    @EnabledOnOs({ OS.LINUX, OS.MAC })
+    public void whenBuildFilePathUsingFileClass_thenOutputIsAsExpected() {
+        File file = new File("file1", "file2");
+        assertEquals("file1/file2", file.toString());
+    }
+}
\ No newline at end of file
diff --git a/core-java-modules/pom.xml b/core-java-modules/pom.xml
index 0a9e818156..711d1e03b9 100644
--- a/core-java-modules/pom.xml
+++ b/core-java-modules/pom.xml
@@ -67,6 +67,7 @@
         <module>core-java-io</module>
         <module>core-java-io-2</module>
         <module>core-java-io-3</module>
+		<module>core-java-io-4</module>
         <module>core-java-io-apis</module>
         <module>core-java-io-conversions</module>
         <module>core-java-io-conversions-2</module>