diff --git a/src/main/java/chapter11/bystander/Bystander.java b/src/main/java/chapter11/bystander/Bystander.java
index 732f8e2..132ba43 100644
--- a/src/main/java/chapter11/bystander/Bystander.java
+++ b/src/main/java/chapter11/bystander/Bystander.java
@@ -1,9 +1,8 @@
 package chapter11.bystander;
 
-public class Bystander extends RightShoe
-{
-    public void learn(Dance dance)
-    {
+public class Bystander extends RightShoe {
+    @Override
+    public void learn(Dance dance) {
         setSteps("-1 -7 ");
     }
 }
diff --git a/src/main/java/chapter11/bystander/BystanderRunner.java b/src/main/java/chapter11/bystander/BystanderRunner.java
index ece46ba..8f56340 100644
--- a/src/main/java/chapter11/bystander/BystanderRunner.java
+++ b/src/main/java/chapter11/bystander/BystanderRunner.java
@@ -3,16 +3,14 @@
 import info.gridworld.actor.ActorWorld;
 import info.gridworld.grid.Location;
 
-public class BystanderRunner extends CongaNumber
-{
+public class BystanderRunner extends CongaNumber {
     @Override
-    public void setUpDancers(ActorWorld world)
-    {
+    public void setUpDancers(ActorWorld world) {
         super.setUpDancers(world);
         world.add(new Location(0, 9), new Bystander());
     }
-    public static void main(String[] args)
-    {
+
+    public static void main(String[] args) {
         DanceNumber number = new BystanderRunner();
         number.run(new ActorWorld(), new Conga());
     }
diff --git a/src/main/java/chapter11/bystander/Conga.java b/src/main/java/chapter11/bystander/Conga.java
index 0e36fdd..0fb331b 100644
--- a/src/main/java/chapter11/bystander/Conga.java
+++ b/src/main/java/chapter11/bystander/Conga.java
@@ -1,24 +1,30 @@
 package chapter11.bystander;
 
-public class Conga implements Dance
-{
-  private static String[] steps =
-    {
-      "00 -- 00 -- -- 77 -- 02 37 -- 40 -- -- 37 -- 41 ",
-      "-- 00 -- 07 00 -- 01 -- -- 40 -- 47 40 -- 41 -- ",
-      "00 -- 00 -- -- 77 -- 02 37 -- 40 -- -- 37 -- 41 ",
-      "-- 00 -- 07 00 -- 01 -- -- 40 -- 47 40 -- 41 -- ",
-      "00 -- 01 -- -- 37 -- 40 00 -- 07 -- -- 51 -- 40 ",
-      "60 -- 60 -- -- 60 -- 64 60 -- 60 -- -- 60 -- 64 ",
-    };
+public class Conga implements Dance {
+    private static String[] steps =
+            {
+                    "00 -- 00 -- -- 77 -- 02 37 -- 40 -- -- 37 -- 41 ",
+                    "-- 00 -- 07 00 -- 01 -- -- 40 -- 47 40 -- 41 -- ",
+                    "00 -- 00 -- -- 77 -- 02 37 -- 40 -- -- 37 -- 41 ",
+                    "-- 00 -- 07 00 -- 01 -- -- 40 -- 47 40 -- 41 -- ",
+                    "00 -- 01 -- -- 37 -- 40 00 -- 07 -- -- 51 -- 40 ",
+                    "60 -- 60 -- -- 60 -- 64 60 -- 60 -- -- 60 -- 64 ",
+            };
 
-  private static int[] beat = {2, 2, 1, 1};
+    private static int[] beat = {2, 2, 1, 1};
 
-  public String getName()
-  {
-    return "Conga";
-  }
+    @Override
+    public String getName() {
+        return "Conga";
+    }
 
-  public String getSteps(int m) { return steps[m-1]; }
-  public int[] getBeat() { return beat; }
-}
+    @Override
+    public String getSteps(int m) {
+        return steps[m - 1];
+    }
+
+    @Override
+    public int[] getBeat() {
+        return beat;
+    }
+}
\ No newline at end of file
diff --git a/src/main/java/chapter11/bystander/CongaNumber.java b/src/main/java/chapter11/bystander/CongaNumber.java
index bcdb7e9..891ebb5 100644
--- a/src/main/java/chapter11/bystander/CongaNumber.java
+++ b/src/main/java/chapter11/bystander/CongaNumber.java
@@ -2,28 +2,27 @@
 
 import info.gridworld.actor.ActorWorld;
 import info.gridworld.grid.Location;
+
 import java.awt.Color;
 
-public class CongaNumber extends DanceNumber
-{
-  public void setUpDancers(ActorWorld world)
-  {
-    super.setUpDancers(world);
+public class CongaNumber extends DanceNumber {
+    @Override
+    public void setUpDancers(ActorWorld world) {
+        super.setUpDancers(world);
 
-    world.add(new Location(5, 3), new LeftSandal());
-    world.add(new Location(5, 4), new RightSandal());
-    world.add(new Location(5, 6), new LeftShoe());
-    world.add(new Location(5, 7), new RightShoe());
-    world.add(new Location(7, 2), new DancingBug(Color.YELLOW));
-    world.add(new Location(7, 4), new DancingBug(Color.GREEN));
-    world.add(new Location(7, 6), new DancingBug(Color.YELLOW));
-    world.add(new Location(7, 8), new DancingBug());
-    world.add(new Location(8, 6), new DancingCrab());
-  }
+        world.add(new Location(5, 3), new LeftSandal());
+        world.add(new Location(5, 4), new RightSandal());
+        world.add(new Location(5, 6), new LeftShoe());
+        world.add(new Location(5, 7), new RightShoe());
+        world.add(new Location(7, 2), new DancingBug(Color.YELLOW));
+        world.add(new Location(7, 4), new DancingBug(Color.GREEN));
+        world.add(new Location(7, 6), new DancingBug(Color.YELLOW));
+        world.add(new Location(7, 8), new DancingBug());
+        world.add(new Location(8, 6), new DancingCrab());
+    }
 
-  public static void main(String[] args)
-  {
-    DanceNumber number = new CongaNumber();
-    number.run(new ActorWorld(), new Conga());
-  }
+    public static void main(String[] args) {
+        DanceNumber number = new CongaNumber();
+        number.run(new ActorWorld(), new Conga());
+    }
 }
diff --git a/src/main/java/chapter11/bystander/Dance.java b/src/main/java/chapter11/bystander/Dance.java
index 9e80806..cfa2d1c 100644
--- a/src/main/java/chapter11/bystander/Dance.java
+++ b/src/main/java/chapter11/bystander/Dance.java
@@ -1,8 +1,9 @@
 package chapter11.bystander;
 
-public interface Dance
-{
-  String getName();
-  String getSteps(int m);
-  int[] getBeat();
+public interface Dance {
+    String getName();
+
+    String getSteps(int m);
+
+    int[] getBeat();
 }
diff --git a/src/main/java/chapter11/bystander/DanceNumber.java b/src/main/java/chapter11/bystander/DanceNumber.java
index 944d889..f27891f 100644
--- a/src/main/java/chapter11/bystander/DanceNumber.java
+++ b/src/main/java/chapter11/bystander/DanceNumber.java
@@ -5,36 +5,31 @@
 import info.gridworld.grid.Grid;
 import info.gridworld.grid.Location;
 
-public class DanceNumber
-{
-  public void setUpDancers(ActorWorld world)
-  {
-    world.add(new Location(0, 0), new Maracas());
-  }
+public class DanceNumber {
+    public void setUpDancers(ActorWorld world) {
+        world.add(new Location(0, 0), new Maracas());
+    }
 
-  public void teach(ActorWorld world, Dance dance)
-  {
-    world.setMessage(dance.getName());
+    public void teach(ActorWorld world, Dance dance) {
+        world.setMessage(dance.getName());
 
-    Grid<Actor> gr = world.getGrid();
-    for (Location loc : gr.getOccupiedLocations())
-    {
-      Actor a = gr.get(loc);
-      if (a instanceof Dancer)
-        ((Dancer)a).learn(dance);
+        Grid<Actor> gr = world.getGrid();
+        for (Location loc : gr.getOccupiedLocations()) {
+            Actor a = gr.get(loc);
+            if (a instanceof Dancer) {
+                ((Dancer) a).learn(dance);
+            }
+        }
     }
-  }
 
-  public void run(ActorWorld world, Dance dance)
-  {
-    setUpDancers(world);
-    teach(world, dance);
-    world.show();
-  }
+    public void run(ActorWorld world, Dance dance) {
+        setUpDancers(world);
+        teach(world, dance);
+        world.show();
+    }
 
-  public static void main(String[] args)
-  {
-    DanceNumber number = new DanceNumber();
-    number.run(new ActorWorld(), new MusicOnly());
-  }
-}
+    public static void main(String[] args) {
+        DanceNumber number = new DanceNumber();
+        number.run(new ActorWorld(), new MusicOnly());
+    }
+}
\ No newline at end of file
diff --git a/src/main/java/chapter11/bystander/DanceRunner.java b/src/main/java/chapter11/bystander/DanceRunner.java
index 9eb52c3..6139746 100644
--- a/src/main/java/chapter11/bystander/DanceRunner.java
+++ b/src/main/java/chapter11/bystander/DanceRunner.java
@@ -1,18 +1,12 @@
 package chapter11.bystander;
 
-public class DanceRunner
-{
-  public static void main(String[] args)
-  {
-    int k = (int)(3 * Math.random());
-    switch (k)
-    {
-      case 0:
-        WaltzNumber.main(args); break;
-      case 1:
-        YMCANumber.main(args); break;
-      case 2:
-        CongaNumber.main(args); break;
+public class DanceRunner {
+    public static void main(String[] args) {
+        int k = (int) (3 * Math.random());
+        switch (k) {
+            case 0 -> WaltzNumber.main(args);
+            case 1 -> YMCANumber.main(args);
+            case 2 -> CongaNumber.main(args);
+        }
     }
-  }
 }
\ No newline at end of file
diff --git a/src/main/java/chapter11/bystander/Dancer.java b/src/main/java/chapter11/bystander/Dancer.java
index f635193..d06e341 100644
--- a/src/main/java/chapter11/bystander/Dancer.java
+++ b/src/main/java/chapter11/bystander/Dancer.java
@@ -2,61 +2,55 @@
 
 import info.gridworld.actor.Actor;
 import info.gridworld.grid.Location;
+
 import java.awt.Color;
 
-public abstract class Dancer extends Actor
-{
-  private String steps;
-  private int stepsCount;
-
-  public Dancer()
-  {
-    setColor(null);
-  }
-
-  public Dancer(Color color)
-  {
-    setColor(color);
-  }
-
-  public void setSteps(String steps)
-  {
-    this.steps = steps;
-    stepsCount = 0;
-  }
-
-  public void act()
-  {
-    if (getGrid() != null && steps != null)
-    {
-      takeStep(steps.substring(stepsCount, stepsCount + 3));
-      stepsCount += 3;
-      if (stepsCount >= steps.length() - 2)
+public abstract class Dancer extends Actor {
+    private String steps;
+    private int stepsCount;
+
+    public Dancer() {
+        setColor(null);
+    }
+
+    public Dancer(Color color) {
+        setColor(color);
+    }
+
+    public void setSteps(String steps) {
+        this.steps = steps;
         stepsCount = 0;
     }
-  }
-
-  private void takeStep(String step)
-  {
-    char d = step.charAt(0);
-    if (Character.isDigit(d))
-    {
-      int dir = Character.digit(d, 10) * 45;
-      Location loc = getLocation();
-      Location next = loc.getAdjacentLocation(getDirection() + dir);
-      if (getGrid().isValid(next))
-        moveTo(next);
-      else
-        removeSelfFromGrid();
+
+    public void act() {
+        if (getGrid() != null && steps != null) {
+            takeStep(steps.substring(stepsCount, stepsCount + 3));
+            stepsCount += 3;
+            if (stepsCount >= steps.length() - 2) {
+                stepsCount = 0;
+            }
+        }
     }
 
-    d = step.charAt(1);
-    if (Character.isDigit(d))
-    {
-      int dir = Character.digit(d, 10) * 45;
-      setDirection(getDirection() + dir);
+    private void takeStep(String step) {
+        char d = step.charAt(0);
+        if (Character.isDigit(d)) {
+            int dir = Character.digit(d, 10) * 45;
+            Location loc = getLocation();
+            Location next = loc.getAdjacentLocation(getDirection() + dir);
+            if (getGrid().isValid(next)) {
+                moveTo(next);
+            } else {
+                removeSelfFromGrid();
+            }
+        }
+
+        d = step.charAt(1);
+        if (Character.isDigit(d)) {
+            int dir = Character.digit(d, 10) * 45;
+            setDirection(getDirection() + dir);
+        }
     }
-  }
 
-  public abstract void learn(Dance dance);
+    public abstract void learn(Dance dance);
 }
diff --git a/src/main/java/chapter11/bystander/DancingBug.java b/src/main/java/chapter11/bystander/DancingBug.java
index 007016a..9703b3e 100644
--- a/src/main/java/chapter11/bystander/DancingBug.java
+++ b/src/main/java/chapter11/bystander/DancingBug.java
@@ -2,19 +2,15 @@
 
 import java.awt.Color;
 
-public class DancingBug extends Dancer
-{
-  public DancingBug()
-  {
-  }
+public class DancingBug extends Dancer {
+    public DancingBug() {}
 
-  public DancingBug(Color color)
-  {
-    super(color);
-  }
+    public DancingBug(Color color) {
+        super(color);
+    }
 
-  public void learn(Dance dance)
-  {
-    setSteps(dance.getSteps(5));
-  }
+    @Override
+    public void learn(Dance dance) {
+        setSteps(dance.getSteps(5));
+    }
 }
\ No newline at end of file
diff --git a/src/main/java/chapter11/bystander/DancingCrab.java b/src/main/java/chapter11/bystander/DancingCrab.java
index fa474cc..33de816 100644
--- a/src/main/java/chapter11/bystander/DancingCrab.java
+++ b/src/main/java/chapter11/bystander/DancingCrab.java
@@ -1,9 +1,8 @@
 package chapter11.bystander;
 
-public class DancingCrab extends Dancer
-{
-  public void learn(Dance dance)
-  {
-    setSteps(dance.getSteps(6));
-  }
+public class DancingCrab extends Dancer {
+    @Override
+    public void learn(Dance dance) {
+        setSteps(dance.getSteps(6));
+    }
 }
\ No newline at end of file
diff --git a/src/main/java/chapter11/bystander/EasySound.java b/src/main/java/chapter11/bystander/EasySound.java
index 52a1e12..9c0bbab 100644
--- a/src/main/java/chapter11/bystander/EasySound.java
+++ b/src/main/java/chapter11/bystander/EasySound.java
@@ -9,57 +9,44 @@
 import javax.sound.sampled.LineUnavailableException;
 import javax.sound.sampled.SourceDataLine;
 
-public class EasySound
-{
-  private SourceDataLine line = null;
-  private byte[] audioBytes;
-  private int numBytes;
-
-  public EasySound(String fileName)
-  {
-    File  soundFile = new File(fileName);
-    AudioInputStream audioInputStream = null;
-    try
-    {
-      audioInputStream = AudioSystem.getAudioInputStream(soundFile);
-    }
-    catch (Exception ex)
-    {
-      System.out.println("*** Cannot find " + fileName + " ***");
-      System.exit(1);
+public class EasySound {
+    private SourceDataLine line = null;
+    private byte[] audioBytes;
+    private int numBytes;
+
+    public EasySound(String fileName) {
+        File soundFile = new File(fileName);
+        AudioInputStream audioInputStream = null;
+        try {
+            audioInputStream = AudioSystem.getAudioInputStream(soundFile);
+        } catch (Exception e) {
+            System.out.println("*** Cannot find " + fileName + " ***");
+            System.exit(1);
+        }
+
+        AudioFormat audioFormat = audioInputStream.getFormat();
+        DataLine.Info info = new DataLine.Info(SourceDataLine.class, audioFormat);
+        try {
+            line = (SourceDataLine) AudioSystem.getLine(info);
+            line.open(audioFormat);
+        } catch (LineUnavailableException e) {
+            System.out.println("*** Audio line unavailable ***");
+            System.exit(1);
+        }
+
+        line.start();
+
+        audioBytes = new byte[(int) soundFile.length()];
+
+        try {
+            numBytes = audioInputStream.read(audioBytes, 0, audioBytes.length);
+        } catch (IOException ex) {
+            System.out.println("*** Cannot read " + fileName + " ***");
+            System.exit(1);
+        }
     }
 
-    AudioFormat audioFormat = audioInputStream.getFormat();
-    DataLine.Info info = new DataLine.Info(SourceDataLine.class,
-                         audioFormat);
-    try
-    {
-      line = (SourceDataLine)AudioSystem.getLine(info);
-      line.open(audioFormat);
-    }
-    catch (LineUnavailableException ex)
-    {
-      System.out.println("*** Audio line unavailable ***");
-      System.exit(1);
+    public void play() {
+        line.write(audioBytes, 0, numBytes);
     }
-
-    line.start();
-
-    audioBytes = new byte[(int)soundFile.length()];
-
-    try
-    {
-      numBytes = audioInputStream.read(audioBytes, 0, audioBytes.length);
-    }
-    catch (IOException ex)
-    {
-      System.out.println("*** Cannot read " + fileName + " ***");
-      System.exit(1);
-    }
-  }
-
-  public void play()
-  {
-    line.write(audioBytes, 0, numBytes);
-  }
-}
+}
\ No newline at end of file
diff --git a/src/main/java/chapter11/bystander/LeftSandal.java b/src/main/java/chapter11/bystander/LeftSandal.java
index dc10c65..2a7d369 100644
--- a/src/main/java/chapter11/bystander/LeftSandal.java
+++ b/src/main/java/chapter11/bystander/LeftSandal.java
@@ -1,9 +1,8 @@
 package chapter11.bystander;
 
-public class LeftSandal extends Dancer
-{
-  public void learn(Dance dance)
-  {
-    setSteps(dance.getSteps(3));
-  }
+public class LeftSandal extends Dancer {
+    @Override
+    public void learn(Dance dance) {
+        setSteps(dance.getSteps(3));
+    }
 }
\ No newline at end of file
diff --git a/src/main/java/chapter11/bystander/LeftShoe.java b/src/main/java/chapter11/bystander/LeftShoe.java
index 8a841af..0c9693f 100644
--- a/src/main/java/chapter11/bystander/LeftShoe.java
+++ b/src/main/java/chapter11/bystander/LeftShoe.java
@@ -1,9 +1,8 @@
 package chapter11.bystander;
 
-public class LeftShoe extends Dancer
-{
-  public void learn(Dance dance)
-  {
-    setSteps(dance.getSteps(1));
-  }
+public class LeftShoe extends Dancer {
+    @Override
+    public void learn(Dance dance) {
+        setSteps(dance.getSteps(1));
+    }
 }
diff --git a/src/main/java/chapter11/bystander/Maracas.java b/src/main/java/chapter11/bystander/Maracas.java
index ea7d713..f8014a9 100644
--- a/src/main/java/chapter11/bystander/Maracas.java
+++ b/src/main/java/chapter11/bystander/Maracas.java
@@ -1,37 +1,35 @@
 package chapter11.bystander;
 
-public class Maracas extends Dancer
-{
-  private EasySound[] beatSound;
-  private int[] beat;
-  private int stepsCount;
+public class Maracas extends Dancer {
+    private EasySound[] beatSound;
+    private int[] beat;
+    private int stepsCount;
 
-  public Maracas()
-  {
-    beatSound = new EasySound[3];
-    beatSound[1] = new EasySound("beat1.wav");
-    beatSound[2] = new EasySound("beat2.wav");
-  }
-
-  public void learn(Dance dance)
-  {
-    beat = dance.getBeat();
-    stepsCount = 0;
-    setSteps("21 57 ");
-  }
+    public Maracas() {
+        beatSound = new EasySound[3];
+        beatSound[1] = new EasySound("beat1.wav");
+        beatSound[2] = new EasySound("beat2.wav");
+    }
 
-  public void act()
-  {
-    if (beat != null)
-    {
-      int i = beat[stepsCount];
-      if (i > 0)
-        beatSound[i].play();
-      stepsCount++;
-      if (stepsCount >= beat.length)
+    @Override
+    public void learn(Dance dance) {
+        beat = dance.getBeat();
         stepsCount = 0;
+        setSteps("21 57 ");
     }
-    super.act();
-  }
-}
 
+    @Override
+    public void act() {
+        if (beat != null) {
+            int i = beat[stepsCount];
+            if (i > 0) {
+                beatSound[i].play();
+            }
+            stepsCount++;
+            if (stepsCount >= beat.length) {
+                stepsCount = 0;
+            }
+        }
+        super.act();
+    }
+}
\ No newline at end of file
diff --git a/src/main/java/chapter11/bystander/MusicOnly.java b/src/main/java/chapter11/bystander/MusicOnly.java
index 5403449..f06ac1e 100644
--- a/src/main/java/chapter11/bystander/MusicOnly.java
+++ b/src/main/java/chapter11/bystander/MusicOnly.java
@@ -1,11 +1,18 @@
 package chapter11.bystander;
 
-public class MusicOnly implements Dance
-{
-  private static String[] steps = {"-- "};
-  private static int[] beat = {2};
-
-  public String getName() { return "Music Only"; }
-  public String getSteps(int m) { return steps[m-1]; }
-  public int[] getBeat() { return beat; }
+public class MusicOnly implements Dance {
+    private static String[] steps = {"-- "};
+    private static int[] beat = {2};
+
+    public String getName() {
+        return "Music Only";
+    }
+
+    public String getSteps(int m) {
+        return steps[m - 1];
+    }
+
+    public int[] getBeat() {
+        return beat;
+    }
 }
diff --git a/src/main/java/chapter11/bystander/RightSandal.java b/src/main/java/chapter11/bystander/RightSandal.java
index 082c420..5c07d68 100644
--- a/src/main/java/chapter11/bystander/RightSandal.java
+++ b/src/main/java/chapter11/bystander/RightSandal.java
@@ -1,9 +1,8 @@
 package chapter11.bystander;
 
-public class RightSandal extends Dancer
-{
-  public void learn(Dance dance)
-  {
-    setSteps(dance.getSteps(4));
-  }
+public class RightSandal extends Dancer {
+    @Override
+    public void learn(Dance dance) {
+        setSteps(dance.getSteps(4));
+    }
 }
\ No newline at end of file
diff --git a/src/main/java/chapter11/bystander/RightShoe.java b/src/main/java/chapter11/bystander/RightShoe.java
index e893f1e..414924f 100644
--- a/src/main/java/chapter11/bystander/RightShoe.java
+++ b/src/main/java/chapter11/bystander/RightShoe.java
@@ -1,9 +1,8 @@
 package chapter11.bystander;
 
-public class RightShoe extends Dancer
-{
-  public void learn(Dance dance)
-  {
-    setSteps(dance.getSteps(2));
-  }
+public class RightShoe extends Dancer {
+    @Override
+    public void learn(Dance dance) {
+        setSteps(dance.getSteps(2));
+    }
 }
\ No newline at end of file
diff --git a/src/main/java/chapter11/bystander/Waltz.java b/src/main/java/chapter11/bystander/Waltz.java
index 93d109c..7a53244 100644
--- a/src/main/java/chapter11/bystander/Waltz.java
+++ b/src/main/java/chapter11/bystander/Waltz.java
@@ -1,24 +1,30 @@
 package chapter11.bystander;
 
-public class Waltz implements Dance
-{
-  private static String[] steps =
-    {
-      "00 -- 20 -- 50 -- ",
-      "-- 10 -- 40 -- 60 ",
-      "-- 50 -- 00 -- 20 ",
-      "40 -- 60 -- 10 -- ",
-      "-7 -1 -1 ",
-      "60 60 -2 ",
-    };
+public class Waltz implements Dance {
+    private static String[] steps =
+            {
+                    "00 -- 20 -- 50 -- ",
+                    "-- 10 -- 40 -- 60 ",
+                    "-- 50 -- 00 -- 20 ",
+                    "40 -- 60 -- 10 -- ",
+                    "-7 -1 -1 ",
+                    "60 60 -2 ",
+            };
 
-  private static int[] beat = {1, 2, 2};
+    private static int[] beat = {1, 2, 2};
 
-  public String getName()
-  {
-    return "chapter11.bystander.Waltz";
-  }
+    @Override
+    public String getName() {
+        return "chapter11.bystander.Waltz";
+    }
 
-  public String getSteps(int m) { return steps[m-1]; }
-  public int[] getBeat() { return beat; }
+    @Override
+    public String getSteps(int m) {
+        return steps[m - 1];
+    }
+
+    @Override
+    public int[] getBeat() {
+        return beat;
+    }
 }
diff --git a/src/main/java/chapter11/bystander/WaltzNumber.java b/src/main/java/chapter11/bystander/WaltzNumber.java
index 94743ec..e6d9fe6 100644
--- a/src/main/java/chapter11/bystander/WaltzNumber.java
+++ b/src/main/java/chapter11/bystander/WaltzNumber.java
@@ -4,27 +4,25 @@
 import info.gridworld.actor.Actor;
 import info.gridworld.grid.Location;
 
-public class WaltzNumber extends DanceNumber
-{
-  public void setUpDancers(ActorWorld world)
-  {
-    super.setUpDancers(world);
+public class WaltzNumber extends DanceNumber {
+    @Override
+    public void setUpDancers(ActorWorld world) {
+        super.setUpDancers(world);
 
-    world.add(new Location(4, 5), new LeftShoe());
-    world.add(new Location(4, 6), new RightShoe());
-    Actor leftSandal = new LeftSandal();
-    leftSandal.setDirection(180);
-    world.add(new Location(2, 6), leftSandal);
-    Actor rightSandal = new RightSandal();
-    rightSandal.setDirection(180);
-    world.add(new Location(2, 5), rightSandal);
-    world.add(new Location(6, 3), new DancingBug());
-    world.add(new Location(7, 4), new DancingCrab());
-  }
+        world.add(new Location(4, 5), new LeftShoe());
+        world.add(new Location(4, 6), new RightShoe());
+        Actor leftSandal = new LeftSandal();
+        leftSandal.setDirection(180);
+        world.add(new Location(2, 6), leftSandal);
+        Actor rightSandal = new RightSandal();
+        rightSandal.setDirection(180);
+        world.add(new Location(2, 5), rightSandal);
+        world.add(new Location(6, 3), new DancingBug());
+        world.add(new Location(7, 4), new DancingCrab());
+    }
 
-  public static void main(String[] args)
-  {
-    DanceNumber number = new WaltzNumber();
-    number.run(new ActorWorld(), new Waltz());
-  }
+    public static void main(String[] args) {
+        DanceNumber number = new WaltzNumber();
+        number.run(new ActorWorld(), new Waltz());
+    }
 }
diff --git a/src/main/java/chapter11/bystander/YMCA.java b/src/main/java/chapter11/bystander/YMCA.java
index b54a651..68e94e6 100644
--- a/src/main/java/chapter11/bystander/YMCA.java
+++ b/src/main/java/chapter11/bystander/YMCA.java
@@ -1,24 +1,30 @@
 package chapter11.bystander;
 
-public class YMCA implements Dance
-{
-  private static String[] steps =
-    {
-      "67 31 ",
-      "21 57 ",
-      "67 31 ",
-      "21 57 ",
-      "67 31 21 57 ",
-      "60 60 20 20 20 20 60 60 ",
-    };
+public class YMCA implements Dance {
+    private static String[] steps =
+            {
+                    "67 31 ",
+                    "21 57 ",
+                    "67 31 ",
+                    "21 57 ",
+                    "67 31 21 57 ",
+                    "60 60 20 20 20 20 60 60 ",
+            };
 
-  private static int[] beat = {1, 1, 1, 1, 2, 2, 2, 2};
+    private static int[] beat = {1, 1, 1, 1, 2, 2, 2, 2};
 
-  public String getName()
-  {
-    return "chapter11.bystander.YMCA";
-  }
+    @Override
+    public String getName() {
+        return "chapter11.bystander.YMCA";
+    }
 
-  public String getSteps(int m) { return steps[m-1]; }
-  public int[] getBeat() { return beat; }
+    @Override
+    public String getSteps(int m) {
+        return steps[m - 1];
+    }
+
+    @Override
+    public int[] getBeat() {
+        return beat;
+    }
 }
diff --git a/src/main/java/chapter11/bystander/YMCANumber.java b/src/main/java/chapter11/bystander/YMCANumber.java
index 3ac5e6c..4055bd2 100644
--- a/src/main/java/chapter11/bystander/YMCANumber.java
+++ b/src/main/java/chapter11/bystander/YMCANumber.java
@@ -3,31 +3,32 @@
 import info.gridworld.actor.ActorWorld;
 import info.gridworld.actor.Actor;
 import info.gridworld.grid.Location;
+
 import java.awt.Color;
 
-public class YMCANumber extends DanceNumber
-{
-  public void setUpDancers(ActorWorld world)
-  {
-    super.setUpDancers(world);
+public class YMCANumber extends DanceNumber {
+    @Override
+    public void setUpDancers(ActorWorld world) {
+        super.setUpDancers(world);
 
-    Actor leftSandal = new LeftSandal();
-    leftSandal.setDirection(180);
-    world.add(new Location(1, 5), leftSandal);
-    Actor rightSandal = new RightSandal();
-    rightSandal.setDirection(180);
-    world.add(new Location(1, 4), rightSandal);
-    world.add(new Location(5, 2), new LeftShoe());
-    world.add(new Location(5, 3), new RightShoe());
-    world.add(new Location(5, 7), new DancingBug());
-    world.add(new Location(7, 2), new DancingBug(Color.YELLOW));
-    world.add(new Location(7, 4), new DancingBug(Color.GREEN));
-    world.add(new Location(8, 6), new DancingCrab());
-  }
+        Actor leftSandal = new LeftSandal();
+        leftSandal.setDirection(180);
+        world.add(new Location(1, 5), leftSandal);
+        Actor rightSandal = new RightSandal();
+        rightSandal.setDirection(180);
+        world.add(new Location(1, 4), rightSandal);
+        world.add(new Location(5, 2), new LeftShoe());
+        world.add(new Location(5, 3), new RightShoe());
+        world.add(new Location(5, 7), new DancingBug());
+        world.add(new Location(7, 2), new DancingBug(Color.YELLOW));
+        world.add(new Location(7, 4), new DancingBug(Color.GREEN));
+        world.add(new Location(8, 6), new DancingCrab());
+    }
 
-  public static void main(String[] args)
-  {
-    DanceNumber number = new YMCANumber();
-    number.run(new ActorWorld(), new YMCA());
-  }
+    public static void main(String[] args) {
+        DanceNumber number = new YMCANumber();
+        number.run(new ActorWorld(), new YMCA());
+    }
 }
+
+public @interface
\ No newline at end of file