Android应用实践-数独游戏

数独游戏是一种源自18世纪末的瑞士的游戏，后在美国发展、并在日本得以发扬光大的数学智力拼图游戏。拼图是九宫格（即3格宽×3格高）的正方形状，每一格又细分为一个九宫格。在每一个小九宫格中，分别填上1至9的数字，让整个大九宫格每一列、每一行的数字都不重复。

数独的玩法逻辑简单，数字排列方式千变万化。不少教育者认为数独是锻炼脑筋的好方法，上外语阅读课的时候外教老师就很喜欢带我们玩这个，乐此不疲，老外的教学方式还是很受欢迎的。但是每次玩这个游戏的时候都要发一张数独游戏卡，嫌麻烦，就想着写一个demo放自己手机上，想想那个时候真是好奇心爆棚，碰上很火爆的小游戏都想整一个DIY的Demo，叨叨够了，哈哈，上源码。

一、界面布局

1.主界面

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:background="@color/background" 
    android:layout_height="fill_parent"
    android:layout_width="fill_parent"
    android:padding="30dip" 
    android:orientation="horizontal">
    <LinearLayout
        android:orientation="vertical" 
        android:layout_width="fill_parent"
        android:layout_height="wrap_content"
        android:layout_gravity="center">

        <TextView
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_gravity="center"
            android:layout_marginBottom="25dip"
            android:text="@string/main_title"
            android:textSize="24sp" />

        <Button
            android:id="@+id/continue_button"
            android:layout_width="fill_parent"
            android:layout_height="wrap_content"
            android:text="@string/continue_label" /> 

        <Button
            android:id="@+id/new_button"
            android:layout_width="fill_parent"
            android:layout_height="wrap_content"
            android:text="@string/new_game_label" />

        <Button
            android:id="@+id/about_button"
            android:layout_width="fill_parent"
            android:layout_height="wrap_content"
            android:text="@string/about_label" />

        <Button
            android:id="@+id/exit_button"
            android:layout_width="fill_parent"
            android:layout_height="wrap_content"
            android:text="@string/exit_label" />
    LinearLayout>

LinearLayout>

2.数字键盘布局

<TableLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:id="@+id/keypad"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:orientation="vertical"
    android:background="@color/puzzle_background"
    android:stretchColumns="*" >

    <TableRow >

        <Button
            android:id="@+id/keypad_1"
            android:text="@string/keypad_1" />

        <Button
            android:id="@+id/keypad_2"
            android:text="@string/keypad_2" />

        <Button
            android:id="@+id/keypad_3"
            android:text="@string/keypad_3" />
    TableRow>

    <TableRow >

        <Button
            android:id="@+id/keypad_4"
            android:text="@string/keypad_4" />

        <Button
            android:id="@+id/keypad_5"
            android:text="@string/keypad_5" />

        <Button
            android:id="@+id/keypad_6"
            android:text="@string/keypad_6" />
    TableRow>

    <TableRow >

        <Button
            android:id="@+id/keypad_7"
            android:text="@string/keypad_7" />

        <Button
            android:id="@+id/keypad_8"
            android:text="@string/keypad_8" />

        <Button
            android:id="@+id/keypad_9"
            android:text="@string/keypad_9" />
    TableRow>

TableLayout>

3.游戏提示布局

<ScrollView
    xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="fill_parent"    
    android:layout_height="fill_parent"    
    android:padding="10dip">
    <TextView 
        android:id="@+id/about_content"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="@string/about_text"/>
ScrollView>

二、游戏提示类

package com.dw.gamesuduku;

import android.app.Activity;
import android.os.Bundle;
public class About extends Activity {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        // TODO Auto-generated method stub
        super.onCreate(savedInstanceState);
        setContentView(R.layout.about);
    }
}

三、逻辑实现1

package com.dw.gamesuduku;

import android.app.Activity;
import android.app.Dialog;
import android.os.Bundle;
import android.util.Log;
import android.view.Gravity;
import android.widget.Toast;
public class Game extends Activity {
    private static final String TAG="Sudoku";
    private static final String PREF_PUZZLE="puzzle";
    protected static final int DIFFICULTY_CONTINUE=-1;

    public static final String KEY_DIFFICULTY="difficulty";
    public static final int DIFFICULTY_EASY=0;
    public static final int DIFFICULTY_MEDIUM=1;
    public static final int DIFFICULTY_HARD=2;

    private int puzzle[]=new int[9*9];
    private PuzzleView puzzleView;
    //三种游戏模式
    private static final String easyPuzzle="360000000004230800000004200"+
                                    "070460003820000014500013010"+
                                    "001900000007048300000000045";
    private static final String mediumPuzzle="650000070000506000014000005"+
                                             "007009000002314700000700800"+
                                             "500000630000201000030000097";
    private static final String hardPuzzle="009000000080605020501078000"+
                                           "000000700706040102004000000"+
                                           "000720903090301080000000600";

    private final int used[][][]=new int[9][9][];
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        // TODO Auto-generated method stub
        super.onCreate(savedInstanceState);
        Log.e(TAG, "onCreate");
        int diff=getIntent().getIntExtra(KEY_DIFFICULTY, DIFFICULTY_EASY);
        puzzle=getPuzzle(diff);
        calculateUsedTiles();

        puzzleView=new PuzzleView(this);
        setContentView(puzzleView);
        puzzleView.requestFocus();
        //if the activity is restarted ,do a continue next time
        getIntent().putExtra(KEY_DIFFICULTY, DIFFICULTY_CONTINUE);
    }


    @Override
    protected void onPause() {
        // TODO Auto-generated method stub
        super.onPause();
        Music.stop(this);
        //Save the current puzzle
        getPreferences(MODE_PRIVATE).edit().putString(PREF_PUZZLE, toPuzzleString(puzzle)).commit();
    }

    @Override
    protected void onResume() {
        // TODO Auto-generated method stub
        super.onResume();
        Music.play(this, R.raw.game);
    }

    protected int[] getUsedTiles(int x,int y){
        return used[x][y];
    }

    private void calculateUsedTiles() {
        // TODO Auto-generated method stub
        for (int x = 0; x < 9; x++) {
            for (int y = 0; y < 9; y++) {
                used[x][y]=calculateUsedTiles(x,y);
            }
        }
    }
    private int[] calculateUsedTiles(int x, int y) {
        // TODO Auto-generated method stub
        int c[]=new int[9];
        //horizontal

        for(int i=0;i<9;i++){
            if(i==y)
                continue;
            int t=getTitle(x, i);
            if(t!=0)
                c[t-1]=t;
        }
        //vertical

        for(int i=0;i<9;i++){
            if(i==x)
                continue;
            int t=getTitle(i, y);
            if(t!=0)
                c[t-1]=t;
        }
        //same cell block
        int startx=(x/3)*3;
        int starty=(y/3)*3;
        for(int i=startx;i3;i++){
            for(int j=starty;j3;j++){
                if(i==x&&j==y)
                    continue;
                int t=getTitle(i, j);
                if(t!=0)
                    c[t-1]=t;
            }
        }
        //compress
        int nused=0;
        for (int t : c) {
            if(t!=0)
            nused++;
        }
        int c1[]=new int[nused];
        nused=0;
        for (int t : c) {
            if(t!=0)
                c1[nused++]=t;
        }
        return c1;
    }
    //give a difficulty level
    private int[] getPuzzle(int diff) {
        // TODO Auto-generated method stub
        String puz = null;
        switch (diff) {
        case DIFFICULTY_CONTINUE:
            puz=getPreferences(MODE_PRIVATE).getString(PREF_PUZZLE, easyPuzzle);
            break;
        case DIFFICULTY_HARD:
            puz=hardPuzzle;
            break;
        case DIFFICULTY_MEDIUM:
            puz=mediumPuzzle;
            break;
        case DIFFICULTY_EASY:
            puz=easyPuzzle;
            break;
        }
        return fromPuzzleString(puz);
    }
    //convert an array into a puzzle string
    static private String toPuzzleString(int[] puz){
        StringBuilder buf=new StringBuilder();
        for (int element : puz) {
            buf.append(element);
        }
        return buf.toString();
    }
    //convert a puzzle string to an array
    static protected int[] fromPuzzleString(String string) {
        // TODO Auto-generated method stub
        int[] puz=new int[string.length()];
        for (int i = 0; i < puz.length; i++) {
        puz[i]=string.charAt(i)-'0';
        }
        return puz;
    } 
    public String getTitleString(int x, int y) {
        // TODO Auto-generated method stub
        int v=getTitle(x,y);
        if(v==0)
            return "";
        else
            return String.valueOf(v);
    }
    private int getTitle(int x, int y) {
        // TODO Auto-generated method stub
        return puzzle[y*9+x];
    }
    private void setTitle(int x,int y,int value){
        puzzle[y*9+x]=value;
    }
    //change the tile only if it's a valid move
    protected boolean setTileIfValid(int x, int y, int value) {
        // TODO Auto-generated method stub
        int tiles[]=getUsedTiles(x, y);
        if(value!=0){
            for (int tile : tiles) {
                if(tile==value)
                    return false;
            }
        }
        setTitle(x, y, value);
        calculateUsedTiles();
        return true;

    }
    //open the keypad if there are any valid moves
    protected void showKeypadOrError(int x, int y) {
        // TODO Auto-generated method stub
        int tiles[]=getUsedTiles(x, y);
        if(tiles.length==9){
            Toast toast=Toast.makeText(this, R.string.no_moves_label, Toast.LENGTH_SHORT);
            toast.setGravity(Gravity.BOTTOM, 0, 0);
            toast.show();
        }else{
            Log.d(TAG, "showKeypad:used="+toPuzzleString(tiles));
            Dialog v=new Keypad(this,tiles,puzzleView);
            v.show();
        }
    }
}

四、数字键盘

package com.dw.gamesuduku;

import android.app.Dialog;
import android.content.Context;
import android.os.Bundle;
import android.view.KeyEvent;
import android.view.View;

public class Keypad extends Dialog {

    protected static final String TAG="Sudoku";
    private final View keys[]=new View[9];
    private View keypad;
    private final int useds[];
    private PuzzleView puzzleView;

    public Keypad(Context context,int useds[],PuzzleView puzzleView){
        super(context);
        this.useds=useds;
        this.puzzleView=puzzleView;
    }

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        // TODO Auto-generated method stub
        super.onCreate(savedInstanceState);
        setContentView(R.layout.keypad);
        findViews();
        for (int element : useds) {
            if(element!=0){
                keys[element-1].setVisibility(View.INVISIBLE);
            }
            setListeners();
        }
    }


    @Override
    public boolean onKeyDown(int keyCode, KeyEvent event) {
        // TODO Auto-generated method stub
        int tile=0;
        switch (keyCode) {
        case KeyEvent.KEYCODE_0:
        case KeyEvent.KEYCODE_SPACE:tile=0;break;
        case KeyEvent.KEYCODE_1:tile=1;break;
        case KeyEvent.KEYCODE_2:tile=2;break;
        case KeyEvent.KEYCODE_3:tile=3;break;
        case KeyEvent.KEYCODE_4:tile=4;break;
        case KeyEvent.KEYCODE_5:tile=5;break;
        case KeyEvent.KEYCODE_6:tile=6;break;
        case KeyEvent.KEYCODE_7:tile=7;break;
        case KeyEvent.KEYCODE_8:tile=8;break;
        case KeyEvent.KEYCODE_9:tile=9;break;
        default:
            return super.onKeyDown(keyCode, event);
        }
        if(isValid(tile)){
            returnResult(tile);
        }
        return true;
    }

    private boolean isValid(int tile) {
        // TODO Auto-generated method stub
        for (int t : useds) {
            if(tile==t)
                return false;
        }
        return true;
    }

    private void findViews() {
        // TODO Auto-generated method stub
        keypad=findViewById(R.id.keypad);
        keys[0]=findViewById(R.id.keypad_1);
        keys[1]=findViewById(R.id.keypad_2);
        keys[2]=findViewById(R.id.keypad_3);
        keys[3]=findViewById(R.id.keypad_4);
        keys[4]=findViewById(R.id.keypad_5);
        keys[5]=findViewById(R.id.keypad_6);
        keys[6]=findViewById(R.id.keypad_7);
        keys[7]=findViewById(R.id.keypad_8);
        keys[8]=findViewById(R.id.keypad_9);
    }
    private void setListeners(){
        for(int i=0;ifinal int t=i+1;
            keys[i].setOnClickListener(new View.OnClickListener() {
                @Override
                public void onClick(View arg0) {
                    // TODO Auto-generated method stub
                    returnResult(t);
                }
            });
        }
        keypad.setOnClickListener(new View.OnClickListener() {
            public void onClick(View arg0) {
                // TODO Auto-generated method stub
                returnResult(0);
            }
        });
    }
    private void returnResult(int tile) {
        // TODO Auto-generated method stub
        puzzleView.setSelectedTile(tile);
        dismiss();
    }

}

五、背景音乐

package com.dw.gamesuduku;

import android.content.Context;
import android.media.MediaPlayer;

public class Music {
    private static MediaPlayer mp=null;
    //stop old song and start a new song
    public static void play(Context context,int resource){
        stop(context);
        if(Settings.getMusic(context)){
        mp=MediaPlayer.create(context, resource);
        mp.setLooping(true);
        mp.start();
        }
    }
    //stop the music
    public static void stop(Context context) {
        // TODO Auto-generated method stub
        if(mp!=null){
            mp.stop();
            mp.release();
            mp=null;
        }
    }
}

六、逻辑实现2

package com.dw.gamesuduku;

import android.annotation.SuppressLint;
import android.content.Context;
import android.graphics.Canvas;
import android.graphics.Paint;
import android.graphics.Paint.FontMetrics;
import android.graphics.Paint.Style;
import android.graphics.Rect;
import android.os.Bundle;
import android.os.Parcelable;
import android.util.Log;
import android.view.KeyEvent;
import android.view.MotionEvent;
import android.view.View;
import android.view.animation.AnimationUtils;

@SuppressLint("DrawAllocation")
public class PuzzleView extends View {
    private static final String TAG = "Sudoku";
    private final Game game;

    private float width;
    private float height;
    private int selX;
    private int selY;
    private final Rect selRect = new Rect();

    private static final String SELX="selX";
    private static final String SELY="selY";
    private static final String VIEW_STATE="viewState";
    private static final int ID=42;//any positive int num

    public PuzzleView(Context context) {
        super(context);
        this.game = (Game) context;
        setFocusable(true);
        setFocusableInTouchMode(true);
        setId(ID);
    }

    @Override
    protected void onSizeChanged(int w, int h, int oldw, int oldh) {
        // TODO Auto-generated method stub
        width = w / 9f;
        height = h / 9f;
        getRect(selX, selY, selRect);
        Log.d(TAG, "onSizeChanged:width" + width + ",height" + height);
        super.onSizeChanged(w, h, oldw, oldh);
    }

    //实例状态保存在bundle中，保存当前游戏状态
    @Override
    protected Parcelable onSaveInstanceState() {
        // TODO Auto-generated method stub
        Parcelable p=super.onSaveInstanceState();
        Log.d(TAG, "onSavedInstanceState");
        Bundle bundle=new Bundle();
        bundle.putInt(SELX, selX);
        bundle.putInt(SELY, selY);
        bundle.putParcelable(VIEW_STATE, p);
        return bundle;
    }
     //恢复已经保存的信息
    @Override
    protected void onRestoreInstanceState(Parcelable state) {
        // TODO Auto-generated method stub
        Log.d(TAG, "onRestoreInstanceState");
        Bundle bundle=(Bundle) state;
        select(bundle.getInt(SELX),bundle.getInt(SELY));
        super.onRestoreInstanceState(bundle.getParcelable(VIEW_STATE));
        return;
    }

    @Override
    protected void onDraw(Canvas canvas) {
        // TODO Auto-generated method stub
        // draw background
        Paint background = new Paint();
        background.setColor(getResources().getColor(R.color.puzzle_background));
        canvas.drawRect(0, 0, getWidth(), getHeight(), background);

        // draw board
        Paint dark = new Paint();
        dark.setColor(getResources().getColor(R.color.puzzle_dark));

        Paint hilite = new Paint();
        hilite.setColor(getResources().getColor(R.color.puzzle_hilite));

        Paint light = new Paint();
        light.setColor(getResources().getColor(R.color.puzzle_light));

        // draw minor grid lines
        for (int i = 0; i < 9; i++) {
            canvas.drawLine(0, i * height, getWidth(), i * height, light);
            canvas.drawLine(0, i * height + 1, getWidth(), i * height + 1,
                    hilite);
            canvas.drawLine(i * width, 0, i * width, getHeight(), dark);
            canvas.drawLine(i * width + 1, 0, i * width + 1, getHeight(),
                    hilite);
        }
        // draw major grid lines
        for (int i = 0; i < 9; i++) {
            if (i % 3 != 0)
                continue;
            canvas.drawLine(0, i * height, getWidth(), i * height, dark);
            canvas.drawLine(0, i * height + 1, getWidth(), i * height + 1,
                    hilite);
            canvas.drawLine(i * width, 0, i * width, getHeight(), dark);
            canvas.drawLine(i * width + 1, 0, i * width + 1, getHeight(),
                    hilite);
        }
        // draw numbers
        Paint foreground = new Paint(Paint.ANTI_ALIAS_FLAG);
        foreground.setColor(getResources().getColor(R.color.puzzle_foregroud));
        foreground.setStyle(Style.FILL);
        foreground.setTextSize(height * 0.75f);
        foreground.setTextScaleX(width / height);
        foreground.setTextAlign(Paint.Align.CENTER);
        // draw num in the center of the tile
        FontMetrics fm = foreground.getFontMetrics();
        float x = width / 2;
        float y = height / 2 - (fm.ascent + fm.descent) / 2;
        for (int i = 0; i < 9; i++) {
            for (int j = 0; j < 9; j++) {
                canvas.drawText(this.game.getTitleString(i, j), i * width + x,
                        j * height + y, foreground);
            }
        }
        // draw the selection
        Log.e(TAG, "selRect=" + selRect);
        Paint selected = new Paint();
        selected.setColor(getResources().getColor(R.color.puzzle_selected));
        canvas.drawRect(selRect, selected);

        //draw the hints pick a hint color based on moves left
        //根据每个单元格可填的数目给出不同颜色的提示
        if(Settings.getHints(getContext())){
        Paint hint=new Paint();
        int c[]={getResources().getColor(R.color.puzzle_hint_0),
                getResources().getColor(R.color.puzzle_hint_1),
                getResources().getColor(R.color.puzzle_hint_2),};
        Rect r=new Rect();
        for (int i = 0; i < 9; i++) {
            for (int j = 0; j < 9; j++) {
                int movesleft=9-game.getUsedTiles(i, j).length;
                if(movesleft@Override
    public boolean onKeyDown(int keyCode, KeyEvent event) {
        // TODO Auto-generated method stub
        Log.d(TAG, "onKeyDown:keycode=" + keyCode + ",event=" + event);
        switch (keyCode) {
        case KeyEvent.KEYCODE_DPAD_UP:
            select(selX, selY - 1);
            break;
        case KeyEvent.KEYCODE_DPAD_DOWN:
            select(selX, selY + 1);
            break;
        case KeyEvent.KEYCODE_DPAD_LEFT:
            select(selX - 1, selY);
            break;
        case KeyEvent.KEYCODE_DPAD_RIGHT:
            select(selX + 1, selY);
            break;
        case KeyEvent.KEYCODE_0:
        case KeyEvent.KEYCODE_SPACE:
            setSelectedTile(0);
            break;
        case KeyEvent.KEYCODE_1:
            setSelectedTile(1);
            break;
        case KeyEvent.KEYCODE_2:
            setSelectedTile(2);
            break;
        case KeyEvent.KEYCODE_3:
            setSelectedTile(3);
            break;
        case KeyEvent.KEYCODE_4:
            setSelectedTile(4);
            break;
        case KeyEvent.KEYCODE_5:
            setSelectedTile(5);
            break;
        case KeyEvent.KEYCODE_6:
            setSelectedTile(6);
            break;
        case KeyEvent.KEYCODE_7:
            setSelectedTile(7);
            break;
        case KeyEvent.KEYCODE_8:
            setSelectedTile(8);
            break;
        case KeyEvent.KEYCODE_9:
            setSelectedTile(9);
            break;
        case KeyEvent.KEYCODE_ENTER:
        case KeyEvent.KEYCODE_DPAD_CENTER:
            game.showKeypadOrError(selX, selY);
        default:
            return super.onKeyDown(keyCode, event);
        }
        return true;
    }

    //显示软键盘
    @Override
    public boolean onTouchEvent(MotionEvent event) {
        // TODO Auto-generated method stub
        if(event.getAction()!=MotionEvent.ACTION_DOWN)
        return super.onTouchEvent(event);

        select((int)(event.getX()/width),(int)(event.getY()/height));
        game.showKeypadOrError(selX, selY);
        Log.d(TAG, "onTouchEvent:x"+selX+",y"+selY);
        return true;
    }

    public void setSelectedTile(int tile) {
        // TODO Auto-generated method stub
        //num is not valid for this tile
        Log.d(TAG, "selectedTile:invalid:"+tile);
//      startAnimation(AnimationUtils.loadAnimation(game, R.aims.shake));
        if (game.setTileIfValid(selX, selY, tile)) {
            invalidate();
        } else {
            // num is not invalid for this tile
            Log.d(TAG, "setSelectedTile:invalid " + tile);
        }

    }
    // 首先计算选定区域的x，y坐标，然后再次调用getRect方法计算新的选择矩形
    private void select(int x, int y) {
        // TODO Auto-generated method stub
        invalidate(selRect);// 第一次调用通知原选择的区域需要重绘
        selX = Math.min(Math.max(x, 0), 8);
        selY = Math.min(Math.max(y, 0), 8);
        getRect(selX, selY, selRect);
        invalidate(selRect);// 第二次调用通知新选择的区域也需要重绘
    }

    private void getRect(int x, int y, Rect rect) {
        // TODO Auto-generated method stub
        rect.set((int) (x * width), (int) (y * height),
                (int) (x * width + width), (int) (y * height + height));

    }

}

七、游戏设置

package com.dw.gamesuduku;

import android.app.Activity;
import android.content.Context;
import android.os.Bundle;
import android.preference.PreferenceFragment;
import android.preference.PreferenceManager;

public class Settings extends Activity {
    private static final String OPT_MUSIC="music";
    private static final boolean OPT_MUSIC_DEF=true;
    private static final String OPT_HINTS="hints";
    private static final boolean OPT_HINTS_DEF=true;
    @Override
    public void onCreate(Bundle savedInstanceState) {
        // TODO Auto-generated method stub
        super.onCreate(savedInstanceState);
        getFragmentManager().beginTransaction().replace(android.R.id.content, new PrefsFragement()).commit();
    }
    public static class PrefsFragement extends PreferenceFragment{  
        public void onCreate(Bundle savedInstanceState) {  
            // TODO Auto-generated method stub  
            super.onCreate(savedInstanceState);  
            addPreferencesFromResource(R.xml.settings);
        }  
    }  
    //get the current music option
    public static boolean getMusic(Context context){
        return PreferenceManager.getDefaultSharedPreferences(context).getBoolean(OPT_MUSIC,OPT_MUSIC_DEF);
    }
    //get the current music option
    public static boolean getHints(Context context){
        return PreferenceManager.getDefaultSharedPreferences(context).getBoolean(OPT_HINTS,OPT_HINTS_DEF);
    }
}

八、游戏入口

package com.dw.gamesuduku;

import android.app.Activity;
import android.app.AlertDialog;
import android.content.DialogInterface;
import android.content.Intent;
import android.os.Bundle;
import android.util.Log;
import android.view.Menu;
import android.view.MenuInflater;
import android.view.MenuItem;
import android.view.View;
import android.view.View.OnClickListener;

public class Sudoku extends Activity implements OnClickListener {
    private static final String TAG = "Sudoku";

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        // TODO Auto-generated method stub
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        View continueButton = this.findViewById(R.id.continue_button);
        continueButton.setOnClickListener(this);

        View newButton = this.findViewById(R.id.new_button);
        newButton.setOnClickListener(this);

        View aboutButton = this.findViewById(R.id.about_button);
        aboutButton.setOnClickListener(this);

        View exitButton = this.findViewById(R.id.exit_button);
        exitButton.setOnClickListener(this);
    }

    @Override
    public void onClick(View v) {
        // TODO Auto-generated method stub
        switch (v.getId()) {
        case R.id.continue_button:
            startGame(Game.DIFFICULTY_CONTINUE);
        case R.id.about_button:
            Intent i = new Intent(this, About.class);
            startActivity(i);
            break;
        case R.id.new_button:
            openNewGameDialog();
            break;
        case R.id.exit_button:
            finish();
            break;
        }
    }
    @Override
    protected void onResume() {
        // TODO Auto-generated method stub
        super.onResume();
        Music.play(this, R.raw.welcome);
    }
    @Override
    protected void onPause() {
        // TODO Auto-generated method stub
        super.onPause();
        Music.stop(this);
    }
    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        // TODO Auto-generated method stub

        super.onCreateOptionsMenu(menu);
        MenuInflater inflater = getMenuInflater();
        inflater.inflate(R.menu.menu, menu);
        return true;
    }

    @Override
    public boolean onOptionsItemSelected(MenuItem item) {
        // TODO Auto-generated method stub
        switch (item.getItemId()) {
        case R.id.settings:
            startActivity(new Intent(this, Settings.class));
            return true;
        }
        return false;
    }

    private void openNewGameDialog() {
        // TODO Auto-generated method stub
        new AlertDialog.Builder(this).setTitle(R.string.new_game_title)
                .setItems(R.array.difficulty,
                        new DialogInterface.OnClickListener() {

                            @Override
                            public void onClick(
                                    DialogInterface dialoginterface, int i) {
                                // TODO Auto-generated method stub
                                startGame(i);
                            }
                        }).show();
    }
    protected void startGame(int i) {
        // TODO Auto-generated method stub
        Log.i(TAG, "clicked on"+i);
        Intent intent=new Intent(Sudoku.this,Game.class);
        intent.putExtra(Game.KEY_DIFFICULTY, i);
        startActivity(intent);  
    }
}