diff --git a/docs/坦克大战笔记.docx b/docs/坦克大战笔记.docx
index e0753c6..447d4ab 100644
Binary files a/docs/坦克大战笔记.docx and b/docs/坦克大战笔记.docx differ
diff --git a/src/com/demo/tank/course9/Bullet.java b/src/com/demo/tank/course9/Bullet.java
index 902efe2..897f441 100644
--- a/src/com/demo/tank/course9/Bullet.java
+++ b/src/com/demo/tank/course9/Bullet.java
@@ -7,7 +7,6 @@ import com.demo.tank.util.ResourceManager;
 import java.awt.*;
 
 public class Bullet extends GameObject {
-    private int x, y;
     private Direction direction;
     private static final int SPEED = 10;
     public static final int WIDTH = ResourceManager.bulletD.getWidth();
@@ -29,11 +28,11 @@ public class Bullet extends GameObject {
         GameModel.getInstance().add(this);
     }
 
-    public void paint(Graphics g){
-        if(!live){
+    public void paint(Graphics g) {
+        if (!live) {
             GameModel.getInstance().remove(this);
         }
-        switch (direction){
+        switch (direction) {
             case UP:
                 g.drawImage(ResourceManager.bulletU, x, y, null);
                 break;
@@ -51,19 +50,23 @@ public class Bullet extends GameObject {
     }
 
     private void move() {
-        switch (direction){
-            case UP: y -= SPEED;
+        switch (direction) {
+            case UP:
+                y -= SPEED;
                 break;
-            case DOWN: y += SPEED;
+            case DOWN:
+                y += SPEED;
                 break;
-            case LEFT: x -= SPEED;
+            case LEFT:
+                x -= SPEED;
                 break;
-            case RIGHT: x += SPEED;
+            case RIGHT:
+                x += SPEED;
                 break;
             default:
                 break;
         }
-        if(x < 0 || y < 0 || x > TankFrameV9.GAME_WIDTH || y > TankFrameV9.GAME_HEIGHT){
+        if (x < 0 || y < 0 || x > TankFrameV9.GAME_WIDTH || y > TankFrameV9.GAME_HEIGHT) {
             live = false;
         }
         rect.x = this.x;
@@ -114,4 +117,13 @@ public class Bullet extends GameObject {
         this.group = group;
     }
 
+    @Override
+    public int getWidth() {
+        return WIDTH;
+    }
+
+    @Override
+    public int getHeight() {
+        return HEIGHT;
+    }
 }
diff --git a/src/com/demo/tank/course9/BulletTankCollider.java b/src/com/demo/tank/course9/BulletTankCollider.java
index d943f8f..830199b 100644
--- a/src/com/demo/tank/course9/BulletTankCollider.java
+++ b/src/com/demo/tank/course9/BulletTankCollider.java
@@ -3,22 +3,22 @@ package com.demo.tank.course9;
 public class BulletTankCollider implements Collider {
     @Override
     public void collide(GameObject g1, GameObject g2) {
-        if(g1 instanceof Bullet && g2 instanceof Tank){
+        if (g1 instanceof Bullet && g2 instanceof Tank) {
             Bullet b = (Bullet) g1;
             Tank t = (Tank) g2;
             //关闭队友伤害
-            if(b.getGroup() == t.getGroup()) return;
-            if(b.rect.intersects(t.rect)){
+            if (b.getGroup() == t.getGroup()) return;
+            if (b.rect.intersects(t.rect)) {
                 t.die();
                 b.die();
                 //爆炸
-                int ex = t.getX() + Tank.WIDTH/2 - Explode.WIDTH/2;
-                int ey = t.getY() + Tank.HEIGHT/2 - Explode.HEIGHT/2;
+                int ex = t.getX() + Tank.WIDTH / 2 - Explode.WIDTH / 2;
+                int ey = t.getY() + Tank.HEIGHT / 2 - Explode.HEIGHT / 2;
                 GameModel.getInstance().add(new Explode(ex, ey));
             }
-        }else if(g1 instanceof Tank && g2 instanceof Bullet){
+        } else if (g1 instanceof Tank && g2 instanceof Bullet) {
             collide(g2, g1);
-        }else{
+        } else {
             return;
         }
     }
diff --git a/src/com/demo/tank/course9/BulletWallCollider.java b/src/com/demo/tank/course9/BulletWallCollider.java
index 3071f20..7af4ca5 100644
--- a/src/com/demo/tank/course9/BulletWallCollider.java
+++ b/src/com/demo/tank/course9/BulletWallCollider.java
@@ -3,15 +3,15 @@ package com.demo.tank.course9;
 public class BulletWallCollider implements Collider {
     @Override
     public void collide(GameObject g1, GameObject g2) {
-        if(g1 instanceof Bullet && g2 instanceof Wall){
+        if (g1 instanceof Bullet && g2 instanceof Wall) {
             Bullet b = (Bullet) g1;
             Wall w = (Wall) g2;
-            if(b.rect.intersects(w.rect)){
+            if (b.rect.intersects(w.rect)) {
                 b.die();
             }
-        }else if(g1 instanceof Wall && g2 instanceof Bullet){
+        } else if (g1 instanceof Wall && g2 instanceof Bullet) {
             collide(g2, g1);
-        }else{
+        } else {
             return;
         }
     }
diff --git a/src/com/demo/tank/course9/ColliderChain.java b/src/com/demo/tank/course9/ColliderChain.java
index 3ed6a94..99d2af2 100644
--- a/src/com/demo/tank/course9/ColliderChain.java
+++ b/src/com/demo/tank/course9/ColliderChain.java
@@ -6,19 +6,19 @@ import java.util.List;
 public class ColliderChain {
     private List<Collider> colliders = new LinkedList<>();
 
-    public ColliderChain(){
+    public ColliderChain() {
         add(new BulletTankCollider());
         add(new TankTankCollider());
         add(new BulletWallCollider());
         add(new TankWallCollider());
     }
 
-    public void add(Collider collider){
+    public void add(Collider collider) {
         colliders.add(collider);
     }
 
     public void collide(GameObject g1, GameObject g2) {
-        for (Collider c : colliders){
+        for (Collider c : colliders) {
             c.collide(g1, g2);
         }
     }
diff --git a/src/com/demo/tank/course9/DefaultFireStrategy.java b/src/com/demo/tank/course9/DefaultFireStrategy.java
index ec2d86d..6e6eb4f 100644
--- a/src/com/demo/tank/course9/DefaultFireStrategy.java
+++ b/src/com/demo/tank/course9/DefaultFireStrategy.java
@@ -6,9 +6,15 @@ import com.demo.tank.util.Audio;
 public class DefaultFireStrategy implements FireStrategy {
     @Override
     public void fire(Tank tank) {
-        int bx = tank.getX() + Tank.WIDTH/2 - Bullet.WIDTH/2;
-        int by = tank.getY() + Tank.HEIGHT/2 - Bullet.HEIGHT/2;
-        new Bullet(bx, by, tank.getDir(), tank.getGroup());
+        int bx = tank.getX() + Tank.WIDTH / 2 - Bullet.WIDTH / 2;
+        int by = tank.getY() + Tank.HEIGHT / 2 - Bullet.HEIGHT / 2;
+//        new Bullet(bx, by, tank.getDir(), tank.getGroup());
+//        GameModel.getInstance().add(new RectDecorator(new Bullet(bx, by, tank.getDir(), tank.getGroup())));
+        GameModel.getInstance().add(new RectDecorator(
+                new TailDecorator(
+                        new Bullet(bx, by, tank.getDir(), tank.getGroup())
+                )
+        ));
         if (tank.getGroup() == Group.GOOD) new Thread(() -> new Audio("audio/tank_fire.wav").play()).start();
     }
 }
diff --git a/src/com/demo/tank/course9/Explode.java b/src/com/demo/tank/course9/Explode.java
index 3a8c16d..5cbe9c8 100644
--- a/src/com/demo/tank/course9/Explode.java
+++ b/src/com/demo/tank/course9/Explode.java
@@ -6,7 +6,6 @@ import com.demo.tank.util.ResourceManager;
 import java.awt.*;
 
 public class Explode extends GameObject {
-    private int x, y;
     public static final int WIDTH = ResourceManager.explodes[0].getWidth();
     public static final int HEIGHT = ResourceManager.explodes[0].getHeight();
 
@@ -18,9 +17,9 @@ public class Explode extends GameObject {
         new Thread(() -> new Audio("audio/explode.wav").play()).start();
     }
 
-    public void paint(Graphics g){
+    public void paint(Graphics g) {
         g.drawImage(ResourceManager.explodes[step++], x, y, null);
-        if(step >= ResourceManager.explodes.length){
+        if (step >= ResourceManager.explodes.length) {
             //播放完爆炸效果图片， remove
             GameModel.getInstance().remove(this);
         }
@@ -42,4 +41,11 @@ public class Explode extends GameObject {
         this.y = y;
     }
 
+    public int getWidth() {
+        return WIDTH;
+    }
+
+    public int getHeight() {
+        return HEIGHT;
+    }
 }
diff --git a/src/com/demo/tank/course9/FourDirectionFireStrategy.java b/src/com/demo/tank/course9/FourDirectionFireStrategy.java
index 0b508d1..567665c 100644
--- a/src/com/demo/tank/course9/FourDirectionFireStrategy.java
+++ b/src/com/demo/tank/course9/FourDirectionFireStrategy.java
@@ -7,9 +7,9 @@ import com.demo.tank.util.Audio;
 public class FourDirectionFireStrategy implements FireStrategy {
     @Override
     public void fire(Tank tank) {
-        int bx = tank.getX() + Tank.WIDTH/2 - Bullet.WIDTH/2;
-        int by = tank.getY() + Tank.HEIGHT/2 - Bullet.HEIGHT/2;
-        for(Direction direction : Direction.values()){
+        int bx = tank.getX() + Tank.WIDTH / 2 - Bullet.WIDTH / 2;
+        int by = tank.getY() + Tank.HEIGHT / 2 - Bullet.HEIGHT / 2;
+        for (Direction direction : Direction.values()) {
             new Bullet(bx, by, direction, tank.getGroup());
         }
         if (tank.getGroup() == Group.GOOD) new Thread(() -> new Audio("audio/tank_fire.wav").play()).start();
diff --git a/src/com/demo/tank/course9/GODecorator.java b/src/com/demo/tank/course9/GODecorator.java
new file mode 100644
index 0000000..86dbd86
--- /dev/null
+++ b/src/com/demo/tank/course9/GODecorator.java
@@ -0,0 +1,13 @@
+package com.demo.tank.course9;
+
+import java.awt.*;
+
+public abstract class GODecorator extends GameObject {
+    GameObject go;
+
+    public GODecorator(GameObject go) {
+        this.go = go;
+    }
+
+    public abstract void paint(Graphics g);
+}
diff --git a/src/com/demo/tank/course9/GameModel.java b/src/com/demo/tank/course9/GameModel.java
index 1e05609..9afa2ea 100644
--- a/src/com/demo/tank/course9/GameModel.java
+++ b/src/com/demo/tank/course9/GameModel.java
@@ -10,25 +10,27 @@ import java.util.List;
 
 public class GameModel {
     private static final GameModel GM = new GameModel();
+
     static {
         GM.init();
     }
 
     private List<GameObject> gameObjects = new ArrayList<>();
 
-//    Collider collider = new BulletTankCollider();
+    //    Collider collider = new BulletTankCollider();
 //    Collider collider2 = new TankTankCollider();
     ColliderChain chain = new ColliderChain();
     Tank tank;
 
-    private GameModel(){
+    private GameModel() {
 
     }
-    private void init(){
+
+    private void init() {
         tank = new Tank(380, 660, Direction.UP, Group.GOOD);
         int enemyTankNum = PropertyManager.getInt("enemy.tank.number");
-        for(int i = 0; i < enemyTankNum; i++){
-            add(new Tank(50 + i*80, 200, Direction.DOWN, Group.BAD));
+        for (int i = 0; i < enemyTankNum; i++) {
+            add(new Tank(50 + i * 80, 200, Direction.DOWN, Group.BAD));
         }
         add(new Wall(150, 150, 200, 50));
         add(new Wall(550, 150, 200, 50));
@@ -36,31 +38,31 @@ public class GameModel {
         add(new Wall(550, 300, 50, 200));
     }
 
-    public static GameModel getInstance(){
+    public static GameModel getInstance() {
         return GM;
     }
 
-    public void add(GameObject go){
+    public void add(GameObject go) {
         gameObjects.add(go);
     }
 
-    public void remove(GameObject go){
+    public void remove(GameObject go) {
         gameObjects.remove(go);
     }
 
-    public void paint(Graphics g){
+    public void paint(Graphics g) {
         tank.paint(g);
 
-        for(int i = 0; i< gameObjects.size(); i++){
+        for (int i = 0; i < gameObjects.size(); i++) {
             gameObjects.get(i).paint(g);
         }
 
         //碰撞检测
-        for(int i = 0; i< gameObjects.size(); i++){
-            for(int j=i+1; j< gameObjects.size(); j++){
-               GameObject g1 = gameObjects.get(i);
-               GameObject g2 = gameObjects.get(j);
-               chain.collide(g1, g2);
+        for (int i = 0; i < gameObjects.size(); i++) {
+            for (int j = i + 1; j < gameObjects.size(); j++) {
+                GameObject g1 = gameObjects.get(i);
+                GameObject g2 = gameObjects.get(j);
+                chain.collide(g1, g2);
             }
         }
     }
diff --git a/src/com/demo/tank/course9/GameObject.java b/src/com/demo/tank/course9/GameObject.java
index 21dce58..aad2061 100644
--- a/src/com/demo/tank/course9/GameObject.java
+++ b/src/com/demo/tank/course9/GameObject.java
@@ -4,5 +4,10 @@ import java.awt.*;
 
 public abstract class GameObject {
     int x, y;
+
     public abstract void paint(Graphics g);
+
+    public abstract int getWidth();
+
+    public abstract int getHeight();
 }
diff --git a/src/com/demo/tank/course9/MainV9.java b/src/com/demo/tank/course9/MainV9.java
index 38064b2..dc8fc4a 100644
--- a/src/com/demo/tank/course9/MainV9.java
+++ b/src/com/demo/tank/course9/MainV9.java
@@ -8,7 +8,7 @@ public class MainV9 {
 
 //        new Thread(() -> new Audio("audio/war1.wav").loop()).start();
 
-        while (true){
+        while (true) {
             Thread.sleep(50);
             tf.repaint();
         }
diff --git a/src/com/demo/tank/course9/RectDecorator.java b/src/com/demo/tank/course9/RectDecorator.java
new file mode 100644
index 0000000..feddb5e
--- /dev/null
+++ b/src/com/demo/tank/course9/RectDecorator.java
@@ -0,0 +1,32 @@
+package com.demo.tank.course9;
+
+import java.awt.*;
+
+public class RectDecorator extends GODecorator {
+
+    public RectDecorator(GameObject go) {
+        super(go);
+    }
+
+    @Override
+    public void paint(Graphics g) {
+        //decorator x,y 也要跟随游戏物体 变化
+        this.x = go.x;
+        this.y = go.y;
+        go.paint(g);
+        Color c = g.getColor();
+        g.setColor(Color.MAGENTA);
+        g.drawRect(go.x, go.y, getWidth(), getHeight());
+        g.setColor(c);
+    }
+
+    @Override
+    public int getWidth() {
+        return super.go.getWidth();
+    }
+
+    @Override
+    public int getHeight() {
+        return super.go.getHeight();
+    }
+}
diff --git a/src/com/demo/tank/course9/TailDecorator.java b/src/com/demo/tank/course9/TailDecorator.java
new file mode 100644
index 0000000..d71eac3
--- /dev/null
+++ b/src/com/demo/tank/course9/TailDecorator.java
@@ -0,0 +1,31 @@
+package com.demo.tank.course9;
+
+import java.awt.*;
+
+public class TailDecorator extends GODecorator {
+
+    public TailDecorator(GameObject go) {
+        super(go);
+    }
+
+    @Override
+    public void paint(Graphics g) {
+        go.paint(g);
+        this.x = go.x;
+        this.y = go.y;
+        Color c = g.getColor();
+        g.setColor(Color.WHITE);
+        g.drawLine(go.x, go.y, go.x + getWidth(), go.y + getHeight());
+        g.setColor(c);
+    }
+
+    @Override
+    public int getWidth() {
+        return super.go.getWidth();
+    }
+
+    @Override
+    public int getHeight() {
+        return super.go.getHeight();
+    }
+}
diff --git a/src/com/demo/tank/course9/Tank.java b/src/com/demo/tank/course9/Tank.java
index 2e36d22..0ba0019 100644
--- a/src/com/demo/tank/course9/Tank.java
+++ b/src/com/demo/tank/course9/Tank.java
@@ -8,7 +8,6 @@ import java.awt.*;
 import java.util.Random;
 
 public class Tank extends GameObject {
-    private int x,y;
     int oldX, oldY;
     private Direction dir;
     private static final int SPEED = 8;
@@ -33,7 +32,7 @@ public class Tank extends GameObject {
         rect.width = Tank.WIDTH;
         rect.height = Tank.HEIGHT;
 
-        if(this.group == Group.GOOD) {
+        if (this.group == Group.GOOD) {
 //            String className = PropertyManager.getString("good.tank.fire.strategy");
             try {
                 fireStrategy = (FireStrategy) Class.forName("com.demo.tank.course9.FourDirectionFireStrategy").newInstance();
@@ -42,24 +41,24 @@ public class Tank extends GameObject {
             } catch (InstantiationException e) {
                 e.printStackTrace();
             } catch (IllegalAccessException e) {
-               e.printStackTrace();
+                e.printStackTrace();
             }
-        }else if(this.group == Group.BAD) fireStrategy = new DefaultFireStrategy();
+        } else if (this.group == Group.BAD) fireStrategy = new DefaultFireStrategy();
     }
 
     @Override
     public void paint(Graphics g) {
-        if(!living) GameModel.getInstance().remove(this);
+        if (!living) GameModel.getInstance().remove(this);
         //根据方向绘制坦克
-        switch (dir){
+        switch (dir) {
             case UP:
                 g.drawImage(this.group == Group.GOOD ? ResourceManager.tankU : ResourceManager.badTankU, x, y, null);
-            break;
+                break;
             case DOWN:
                 g.drawImage(this.group == Group.GOOD ? ResourceManager.tankD : ResourceManager.badTankD, x, y, null);
                 break;
             case LEFT:
-                g.drawImage(this.group == Group.GOOD ? ResourceManager.tankL: ResourceManager.badTankL, x, y, null);
+                g.drawImage(this.group == Group.GOOD ? ResourceManager.tankL : ResourceManager.badTankL, x, y, null);
                 break;
             case RIGHT:
                 g.drawImage(this.group == Group.GOOD ? ResourceManager.tankR : ResourceManager.badTankR, x, y, null);
@@ -68,28 +67,32 @@ public class Tank extends GameObject {
         move();
     }
 
-    public void move(){
+    public void move() {
         oldX = x;
         oldY = y;
         //如果没有移动 return
-        if(!moving) return;
-        switch (dir){
-            case UP: y -= SPEED;
+        if (!moving) return;
+        switch (dir) {
+            case UP:
+                y -= SPEED;
                 break;
-            case DOWN: y += SPEED;
+            case DOWN:
+                y += SPEED;
                 break;
-            case LEFT: x -= SPEED;
+            case LEFT:
+                x -= SPEED;
                 break;
-            case RIGHT: x += SPEED;
+            case RIGHT:
+                x += SPEED;
                 break;
             default:
                 break;
         }
-        if(this.group == Group.BAD) {
-            if(random.nextInt(10) == 5){
+        if (this.group == Group.BAD) {
+            if (random.nextInt(10) == 5) {
                 this.fire();
             }
-            if(random.nextInt(100) > 95){
+            if (random.nextInt(100) > 95) {
                 this.randomDirection();
             }
         }
@@ -101,27 +104,27 @@ public class Tank extends GameObject {
         rect.y = this.y;
     }
 
-    public void back(){
+    public void back() {
         this.x = oldX;
         this.y = oldY;
     }
 
     private void boundsCheck() {
-        if(x < 0) x = 0;
-        if(x > TankFrameV9.GAME_WIDTH - Tank.WIDTH) x = TankFrameV9.GAME_WIDTH - Tank.WIDTH;
-        if(y < 30) y = 30; //算上菜单条
-        if(y > TankFrameV9.GAME_HEIGHT - Tank.HEIGHT) y = TankFrameV9.GAME_HEIGHT - Tank.HEIGHT;
+        if (x < 0) x = 0;
+        if (x > TankFrameV9.GAME_WIDTH - Tank.WIDTH) x = TankFrameV9.GAME_WIDTH - Tank.WIDTH;
+        if (y < 30) y = 30; //算上菜单条
+        if (y > TankFrameV9.GAME_HEIGHT - Tank.HEIGHT) y = TankFrameV9.GAME_HEIGHT - Tank.HEIGHT;
     }
 
     private void randomDirection() {
-          this.dir = Direction.values()[random.nextInt(4)];
+        this.dir = Direction.values()[random.nextInt(4)];
     }
 
     public void fire() {
-       fireStrategy.fire(this);
+        fireStrategy.fire(this);
     }
 
-    public void die(){
+    public void die() {
         this.living = false;
     }
 
@@ -181,4 +184,12 @@ public class Tank extends GameObject {
         this.rect = rect;
     }
 
+    public int getWidth() {
+        return WIDTH;
+    }
+
+    public int getHeight() {
+        return HEIGHT;
+    }
+
 }
diff --git a/src/com/demo/tank/course9/TankFrameV9.java b/src/com/demo/tank/course9/TankFrameV9.java
index 29ec300..29d4a9f 100644
--- a/src/com/demo/tank/course9/TankFrameV9.java
+++ b/src/com/demo/tank/course9/TankFrameV9.java
@@ -14,9 +14,9 @@ public class TankFrameV9 extends Frame {
     public static final int GAME_HEIGHT = 800;
     Image image = null;
 
-    public TankFrameV9(){
+    public TankFrameV9() {
         setVisible(true);
-        setBounds(400, 100 , GAME_WIDTH, GAME_HEIGHT);
+        setBounds(400, 100, GAME_WIDTH, GAME_HEIGHT);
         setResizable(false);
         setTitle("tank war");
         this.addKeyListener(new MyKeyListener());
@@ -30,24 +30,24 @@ public class TankFrameV9 extends Frame {
 
     @Override
     public void update(Graphics g) {
-        if(image == null){
+        if (image == null) {
             image = this.createImage(GAME_WIDTH, GAME_HEIGHT);
         }
-        Graphics imgGraphic =  image.getGraphics();
+        Graphics imgGraphic = image.getGraphics();
         Color color = g.getColor();
         imgGraphic.setColor(Color.BLACK);
-        imgGraphic.fillRect(0,0, GAME_WIDTH, GAME_HEIGHT);
+        imgGraphic.fillRect(0, 0, GAME_WIDTH, GAME_HEIGHT);
         imgGraphic.setColor(color);
         paint(imgGraphic);
         g.drawImage(image, 0, 0, null);
     }
 
     @Override
-    public void paint(Graphics g){
+    public void paint(Graphics g) {
         gm.paint(g);
     }
 
-    class MyKeyListener extends KeyAdapter{
+    class MyKeyListener extends KeyAdapter {
         boolean bL = false;
         boolean bR = false;
         boolean bU = false;
@@ -55,7 +55,7 @@ public class TankFrameV9 extends Frame {
 
         @Override
         public void keyPressed(KeyEvent e) {
-            switch (e.getKeyCode()){
+            switch (e.getKeyCode()) {
                 case KeyEvent.VK_A:
                     bL = true;
                     break;
@@ -63,8 +63,8 @@ public class TankFrameV9 extends Frame {
                     bR = true;
                     break;
                 case KeyEvent.VK_W:
-                        bU = true;
-                        break;
+                    bU = true;
+                    break;
                 case KeyEvent.VK_S:
                     bD = true;
                     break;
@@ -76,7 +76,7 @@ public class TankFrameV9 extends Frame {
 
         @Override
         public void keyReleased(KeyEvent e) {
-            switch (e.getKeyCode()){
+            switch (e.getKeyCode()) {
                 case KeyEvent.VK_A:
                     bL = false;
                     break;
@@ -98,15 +98,15 @@ public class TankFrameV9 extends Frame {
             setTankDirection();
         }
 
-        public void setTankDirection(){
-            if(!bL && !bR && !bU && !bD){
+        public void setTankDirection() {
+            if (!bL && !bR && !bU && !bD) {
                 gm.tank.setMoving(false);
-            }else{
+            } else {
                 gm.tank.setMoving(true);
-                if(bL) gm.tank.setDir(Direction.LEFT);
-                if(bR) gm.tank.setDir(Direction.RIGHT);
-                if(bU) gm.tank.setDir(Direction.UP);
-                if(bD) gm.tank.setDir(Direction.DOWN);
+                if (bL) gm.tank.setDir(Direction.LEFT);
+                if (bR) gm.tank.setDir(Direction.RIGHT);
+                if (bU) gm.tank.setDir(Direction.UP);
+                if (bD) gm.tank.setDir(Direction.DOWN);
             }
         }
     }
diff --git a/src/com/demo/tank/course9/TankTankCollider.java b/src/com/demo/tank/course9/TankTankCollider.java
index 310016a..b2101b0 100644
--- a/src/com/demo/tank/course9/TankTankCollider.java
+++ b/src/com/demo/tank/course9/TankTankCollider.java
@@ -4,17 +4,18 @@ import java.util.Random;
 
 public class TankTankCollider implements Collider {
     Random random = new Random();
+
     @Override
     public void collide(GameObject g1, GameObject g2) {
-        if(g1 instanceof Tank && g2 instanceof Tank){
+        if (g1 instanceof Tank && g2 instanceof Tank) {
             Tank t1 = (Tank) g1;
             Tank t2 = (Tank) g2;
-            if(t1.rect.intersects(t2.rect)){
+            if (t1.rect.intersects(t2.rect)) {
                 // simple deal
                 t1.back();
                 t2.back();
             }
-        }else{
+        } else {
             return;
         }
     }
diff --git a/src/com/demo/tank/course9/TankWallCollider.java b/src/com/demo/tank/course9/TankWallCollider.java
index 773713d..f685938 100644
--- a/src/com/demo/tank/course9/TankWallCollider.java
+++ b/src/com/demo/tank/course9/TankWallCollider.java
@@ -1,17 +1,17 @@
 package com.demo.tank.course9;
 
-public class TankWallCollider implements Collider{
+public class TankWallCollider implements Collider {
     @Override
     public void collide(GameObject g1, GameObject g2) {
-        if(g1 instanceof Tank && g2 instanceof Wall){
+        if (g1 instanceof Tank && g2 instanceof Wall) {
             Tank t = (Tank) g1;
             Wall w = (Wall) g2;
-            if(t.rect.intersects(w.rect)){
+            if (t.rect.intersects(w.rect)) {
                 t.back();
             }
-        }else if(g1 instanceof Wall && g2 instanceof Bullet){
+        } else if (g1 instanceof Wall && g2 instanceof Bullet) {
             collide(g2, g1);
-        }else{
+        } else {
             return;
         }
     }
diff --git a/src/com/demo/tank/course9/Wall.java b/src/com/demo/tank/course9/Wall.java
index 60910db..f94fb0d 100644
--- a/src/com/demo/tank/course9/Wall.java
+++ b/src/com/demo/tank/course9/Wall.java
@@ -2,7 +2,7 @@ package com.demo.tank.course9;
 
 import java.awt.*;
 
-public class Wall extends GameObject{
+public class Wall extends GameObject {
     int width, height;
     Rectangle rect;
 
@@ -21,4 +21,12 @@ public class Wall extends GameObject{
         g.fillRect(x, y, width, height);
         g.setColor(c);
     }
+
+    public int getWidth() {
+        return width;
+    }
+
+    public int getHeight() {
+        return height;
+    }
 }