Add all 23 GoF design pattern implementations (2026-06-13)

02-structural/bridge/AdvancedRemote.java

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+package bridge;
+
+/**
+ * Refined Abstraction — extends RemoteControl with extra features.
+ * This is how you vary the "abstraction" side independently of the
+ * "implementation" side. Both TV and Radio work with this remote,
+ * even though they know nothing about it.
+ */
+public class AdvancedRemote extends RemoteControl {
+
+    public AdvancedRemote(Device device) {
+        super(device);
+    }
+
+    // Extra feature not in the basic remote
+    public void mute() {
+        System.out.println("  Muting " + device.getName());
+        device.setVolume(0);
+    }
+
+    public void jumpToChannel(int channel) {
+        System.out.println("  Jumping to channel " + channel);
+        device.setChannel(channel);
+    }
+}

02-structural/bridge/Device.java

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+package bridge;
+
+/**
+ * Implementor interface — the "implementation" side of the bridge.
+ * This is what the Abstraction delegates its real work to.
+ * TV, Radio, SmartSpeaker etc. all implement this.
+ */
+public interface Device {
+    boolean isEnabled();
+    void enable();
+    void disable();
+    int getVolume();
+    void setVolume(int percent);
+    int getChannel();
+    void setChannel(int channel);
+    String getName();
+}

02-structural/bridge/Main.java

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+package bridge;
+
+/**
+ * Bridge Design Pattern — Runnable Demo
+ *
+ * Shows how remotes (abstraction) and devices (implementation)
+ * can vary independently. 4 combinations from 2+2 classes,
+ * not 4 hard-coded classes.
+ *
+ * Run: javac bridge/*.java && java bridge.Main
+ * Article: https://ankurm.com/bridge-design-pattern-java/
+ */
+public class Main {
+
+    public static void main(String[] args) {
+        System.out.println("=== Bridge Design Pattern Demo ===\n");
+
+        // Combination 1: Basic Remote + TV
+        System.out.println("-- Basic Remote controlling TV --");
+        RemoteControl remote1 = new RemoteControl(new TV());
+        remote1.togglePower();
+        remote1.volumeUp();
+        remote1.channelUp();
+
+        System.out.println();
+
+        // Combination 2: Advanced Remote + Radio
+        System.out.println("-- Advanced Remote controlling Radio --");
+        AdvancedRemote remote2 = new AdvancedRemote(new Radio());
+        remote2.togglePower();
+        remote2.volumeUp();
+        remote2.mute();
+        remote2.jumpToChannel(91);
+
+        System.out.println();
+
+        // Combination 3: Advanced Remote + TV (no new classes needed)
+        System.out.println("-- Advanced Remote controlling TV --");
+        AdvancedRemote remote3 = new AdvancedRemote(new TV());
+        remote3.togglePower();
+        remote3.jumpToChannel(5);
+        remote3.mute();
+
+        System.out.println("\n=== Demo complete ===");
+        System.out.println("3 different remote+device combinations, 0 new classes needed.");
+    }
+}

02-structural/bridge/README.md

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+# Bridge Design Pattern — Java Example
+
+**Pattern:** Structural → Bridge
+**Article:** https://ankurm.com/bridge-design-pattern-java/
+
+## What this example shows
+
+Decouples remote controls (Abstraction) from devices (Implementation). A basic remote and an advanced remote each work with any device (TV, Radio) without creating N×M subclasses.
+
+## How to run
+
+```bash
+javac bridge/*.java
+java bridge.Main
+```
+
+Requires Java 11+.
+
+## Files
+
+| File | Role |
+|---|---|
+| `Device.java` | Implementor interface |
+| `TV.java` / `Radio.java` | Concrete Implementors |
+| `RemoteControl.java` | Abstraction (holds Device bridge) |
+| `AdvancedRemote.java` | Refined Abstraction |
+| `Main.java` | Demo entry point |
+
+Article: https://ankurm.com/bridge-design-pattern-java/
+All patterns: https://ankurm.com/design-patterns-java/

02-structural/bridge/Radio.java

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+package bridge;
+
+/**
+ * Concrete Implementor — a radio.
+ * Same Device interface, completely different internal behaviour.
+ */
+public class Radio implements Device {
+
+    private boolean on = false;
+    private int volume = 20;
+    private int channel = 1;  // FM frequency index simplified
+
+    @Override public boolean isEnabled() { return on; }
+    @Override public void enable()  { on = true;  System.out.println("  [Radio] Powered ON");  }
+    @Override public void disable() { on = false; System.out.println("  [Radio] Powered OFF"); }
+
+    @Override
+    public int getVolume() { return volume; }
+
+    @Override
+    public void setVolume(int percent) {
+        this.volume = Math.max(0, Math.min(100, percent));
+        System.out.println("  [Radio] Volume set to " + this.volume);
+    }
+
+    @Override public int  getChannel()       { return channel; }
+    @Override public void setChannel(int ch) { this.channel = ch; System.out.println("  [Radio] Frequency -> " + ch); }
+    @Override public String getName()        { return "JBL Radio"; }
+}

02-structural/bridge/RemoteControl.java

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+package bridge;
+
+/**
+ * Abstraction — the remote control. It holds a reference to a Device
+ * (the "bridge") and delegates all real work to it.
+ *
+ * The key: RemoteControl doesn't care whether it talks to a TV or Radio.
+ * It holds a Device and calls Device methods. That's the bridge.
+ */
+public class RemoteControl {
+
+    // The bridge — link from Abstraction to Implementation
+    protected Device device;
+
+    public RemoteControl(Device device) {
+        this.device = device;
+        System.out.println("Remote paired with: " + device.getName());
+    }
+
+    public void togglePower() {
+        if (device.isEnabled()) {
+            device.disable();
+        } else {
+            device.enable();
+        }
+    }
+
+    public void volumeUp()   { device.setVolume(device.getVolume() + 10); }
+    public void volumeDown() { device.setVolume(device.getVolume() - 10); }
+
+    public void channelUp()   { device.setChannel(device.getChannel() + 1); }
+    public void channelDown() { device.setChannel(device.getChannel() - 1); }
+}

02-structural/bridge/TV.java

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+package bridge;
+
+/**
+ * Concrete Implementor — a television.
+ * Contains device-specific logic for a TV.
+ */
+public class TV implements Device {
+
+    private boolean on = false;
+    private int volume = 30;
+    private int channel = 1;
+
+    @Override public boolean isEnabled() { return on; }
+    @Override public void enable()  { on = true;  System.out.println("  [TV] Powered ON");  }
+    @Override public void disable() { on = false; System.out.println("  [TV] Powered OFF"); }
+
+    @Override
+    public int getVolume() { return volume; }
+
+    @Override
+    public void setVolume(int percent) {
+        this.volume = Math.max(0, Math.min(100, percent));
+        System.out.println("  [TV] Volume set to " + this.volume);
+    }
+
+    @Override public int  getChannel()          { return channel; }
+    @Override public void setChannel(int ch)    { this.channel = ch; System.out.println("  [TV] Channel -> " + ch); }
+    @Override public String getName()           { return "Samsung TV"; }
+}