Facade: split subsystem into one class per file, sync post code blocks to Java 25, add README mapping

02-structural/facade/AudioMixer.java

@@ -0,0 +1,9 @@
+package facade;
+
+/** AudioMixer — normalises audio tracks after conversion. */
+class AudioMixer {
+    static VideoFile fix(VideoFile result) {
+        System.out.println("  AudioMixer: fixing audio tracks");
+        return new VideoFile(result.getFilename());
+    }
+}

02-structural/facade/BitrateReader.java

@@ -0,0 +1,15 @@
+package facade;
+
+/** BitrateReader — reads the video buffer and converts it between codecs. */
+class BitrateReader {
+    static VideoFile read(VideoFile file, Codec codec) {
+        System.out.println("  BitrateReader: reading " + file.getFilename()
+                + " with codec " + codec.getName());
+        return new VideoFile(file.getFilename());
+    }
+
+    static VideoFile convert(VideoFile buffer, Codec codec) {
+        System.out.println("  BitrateReader: converting to " + codec.getName());
+        return new VideoFile(buffer.getFilename());
+    }
+}

02-structural/facade/Codec.java

@@ -0,0 +1,6 @@
+package facade;
+
+/** Codec — common interface implemented by each concrete compression codec. */
+interface Codec {
+    String getName();
+}

02-structural/facade/CodecFactory.java

@@ -0,0 +1,10 @@
+package facade;
+
+/** CodecFactory — inspects a VideoFile and returns the matching Codec. */
+class CodecFactory {
+    static Codec extract(VideoFile file) {
+        System.out.println("  CodecFactory: extracting codec from " + file.getFilename());
+        if ("mpeg4".equals(file.getCodecType())) return new MPEG4CompressionCodec();
+        return new OggCompressionCodec();
+    }
+}

02-structural/facade/MPEG4CompressionCodec.java

@@ -0,0 +1,6 @@
+package facade;
+
+/** Concrete Codec: MPEG-4 compression. */
+class MPEG4CompressionCodec implements Codec {
+    @Override public String getName() { return "mpeg4"; }
+}

02-structural/facade/OggCompressionCodec.java

@@ -0,0 +1,6 @@
+package facade;
+
+/** Concrete Codec: Ogg compression. */
+class OggCompressionCodec implements Codec {
+    @Override public String getName() { return "ogg"; }
+}

02-structural/facade/README.md

@@ -0,0 +1,35 @@
+# Facade Design Pattern — Java Example
+
+**Pattern:** Structural → Facade
+**Article:** https://ankurm.com/facade-design-pattern-java/
+
+## What this example shows
+
+A video-conversion subsystem (`VideoFile`, `Codec`, `MPEG4CompressionCodec`, `OggCompressionCodec`, `CodecFactory`, `BitrateReader`, `AudioMixer`) is wrapped behind one class, `VideoConversionFacade`, that exposes a single `convertVideo()` method. Callers never touch the six subsystem classes directly, but they remain public and usable on their own for advanced use cases.
+
+## How to run
+
+```bash
+javac facade/*.java -d out/facade
+java -cp out/facade facade.Main
+```
+
+Requires Java 25.
+
+## Post Section ↔ File Mapping
+
+| Post Section | File(s) |
+|---|---|
+| The Subsystem (Complex, But Unchanged) — VideoFile | `VideoFile.java` |
+| The Subsystem (Complex, But Unchanged) — Codec interface | `Codec.java` |
+| The Subsystem (Complex, But Unchanged) — Concrete Codecs | `MPEG4CompressionCodec.java`, `OggCompressionCodec.java` |
+| The Subsystem (Complex, But Unchanged) — CodecFactory | `CodecFactory.java` |
+| The Subsystem (Complex, But Unchanged) — BitrateReader | `BitrateReader.java` |
+| The Subsystem (Complex, But Unchanged) — AudioMixer | `AudioMixer.java` |
+| The Facade | `VideoConversionFacade.java` |
+| Client Code: One Line | `Main.java` |
+
+Note: the SLF4J `LoggerFactory`, JDBC `DriverManager`, and Spring `JdbcTemplate` snippets under "Facade in the JDK and Real Frameworks" are illustrative only — they are not part of this repository's runnable example.
+
+Article: https://ankurm.com/facade-design-pattern-java/
+All patterns: https://ankurm.com/design-patterns-java/

02-structural/facade/Subsystems.java

@@ -1,62 +0,0 @@
-package facade;
-
-/**
- * Complex subsystem classes — these are what the Facade hides.
- * Each class has its own complex API; clients shouldn't need to know all of them.
- */
-
-class VideoFile {
-    private final String filename;
-    private final String codecType;
-
-    VideoFile(String filename) {
-        this(filename, filename.endsWith(".mp4") ? "mpeg4" : "ogg");
-    }
-
-    VideoFile(String filename, String codec) {
-        this.filename  = filename;
-        this.codecType = codec;
-        System.out.println("  VideoFile: " + filename + " [codec: " + codecType + "]");
-    }
-
-    public String getFilename()  { return filename; }
-    public String getCodecType() { return codecType; }
-}
-
-interface Codec { String getName(); }
-
-class MPEG4CompressionCodec implements Codec {
-    @Override public String getName() { return "mpeg4"; }
-}
-
-class OggCompressionCodec implements Codec {
-    @Override public String getName() { return "ogg"; }
-}
-
-class CodecFactory {
-    static Codec extract(VideoFile file) {
-        System.out.println("  CodecFactory: extracting codec from " + file.getFilename());
-        if ("mpeg4".equals(file.getCodecType())) return new MPEG4CompressionCodec();
-        return new OggCompressionCodec();
-    }
-}
-
-class BitrateReader {
-    static VideoFile read(VideoFile file, Codec codec) {
-        System.out.println("  BitrateReader: reading " + file.getFilename()
-                + " with codec " + codec.getName());
-        return new VideoFile(file.getFilename());
-    }
-
-    static VideoFile convert(VideoFile buffer, Codec codec) {
-        System.out.println("  BitrateReader: converting to " + codec.getName());
-        return new VideoFile(buffer.getFilename());
-    }
-}
-
-class AudioMixer {
-    static VideoFile fix(VideoFile result) {
-        System.out.println("  AudioMixer: fixing audio tracks");
-        return new VideoFile(result.getFilename());
-    }
-}

02-structural/facade/VideoFile.java

@@ -0,0 +1,23 @@
+package facade;
+
+/**
+ * Complex subsystem classes — these are what the Facade hides.
+ * Each class has its own complex API; clients shouldn't need to know all of them.
+ */
+class VideoFile {
+    private final String filename;
+    private final String codecType;
+
+    VideoFile(String filename) {
+        this(filename, filename.endsWith(".mp4") ? "mpeg4" : "ogg");
+    }
+
+    VideoFile(String filename, String codec) {
+        this.filename  = filename;
+        this.codecType = codec;
+        System.out.println("  VideoFile: " + filename + " [codec: " + codecType + "]");
+    }
+
+    public String getFilename()  { return filename; }
+    public String getCodecType() { return codecType; }
+}

README.md

@@ -249,6 +249,27 @@ javac 02-structural/decorator/*.java -d out/decorator
 java -cp out/decorator decorator.Main
 ```
 
+### Facade (`02-structural/facade/`)
+
+| Post Section | File(s) |
+|---|---|
+| The Subsystem (Complex, But Unchanged) — VideoFile | `VideoFile.java` |
+| The Subsystem (Complex, But Unchanged) — Codec interface | `Codec.java` |
+| The Subsystem (Complex, But Unchanged) — Concrete Codecs | `MPEG4CompressionCodec.java`, `OggCompressionCodec.java` |
+| The Subsystem (Complex, But Unchanged) — CodecFactory | `CodecFactory.java` |
+| The Subsystem (Complex, But Unchanged) — BitrateReader | `BitrateReader.java` |
+| The Subsystem (Complex, But Unchanged) — AudioMixer | `AudioMixer.java` |
+| The Facade | `VideoConversionFacade.java` |
+| Client Code: One Line | `Main.java` |
+
+Note: the SLF4J `LoggerFactory`, JDBC `DriverManager`, and Spring `JdbcTemplate` snippets under "Facade in the JDK and Real Frameworks" are illustrative only — they are not part of this repository's runnable example.
+
+Run it:
+```bash
+javac 02-structural/facade/*.java -d out/facade
+java -cp out/facade facade.Main
+```
+
 ## Reference
 
 - *Design Patterns: Elements of Reusable Object-Oriented Software* — Gamma, Helm, Johnson, Vlissides