为什么这个SQLite数据库不能正常工作

Question

我想向我的游戏添加前10名高分。高分是由只有两件事 - 得分和难度，但到目前为止，我不很了解如何数据库的作品，但后几个教程我有这个做

public class DBHandler extends SQLiteOpenHelper { 

private static final int DATABASE_VERSION = 1; 

private static final String DATABASE_NAME = "highscores"; 

private static final String TABLE_DETAIL = "scores"; 

private static final String KEY_ID = "id"; 
private static final String KEY_TIME = "time"; 
private static final String KEY_DIFFICULTY = "difficutly"; 


public DBHandler(Context context){ super(context, DATABASE_NAME, null, DATABASE_VERSION);} 

@Override 
public void onCreate(SQLiteDatabase db) { 
    String CREATE_HIGHSCORES_TABLE = "CREATE TABLE " + TABLE_DETAIL + "(" 
      + KEY_ID + " INTEGER PRIMARY KEY, " 
      + KEY_TIME + " TEXT, " 
      + KEY_DIFFICULTY + " TEXT)"; 
    db.execSQL(CREATE_HIGHSCORES_TABLE); 
} 

@Override 
public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) { 
    db.execSQL("DROP TABLE IF EXISTS " + TABLE_DETAIL);  

    onCreate(db);           
} 
// Adding new score 
public void addScore(int score) { 

    SQLiteDatabase db = this.getWritableDatabase(); 

    ContentValues values = new ContentValues(); 

    values.put(KEY_TIME, score); // score value 

    // Inserting Values 
    db.insert(TABLE_DETAIL, null, values); 

    db.close(); 

} 

// Getting All Scores 
public String[] getAllScores() { 

    // Select All Query 
    String selectQuery = "SELECT * FROM " + TABLE_DETAIL; 

    SQLiteDatabase db = this.getWritableDatabase(); 
    Cursor cursor = db.rawQuery(selectQuery, null); 

    // looping through all rows and adding to list 

    int i = 0; 

    String[] data = new String[cursor.getCount()]; 

    while (cursor.moveToNext()) { 

     data[i] = cursor.getString(1); 

     i = i++; 

    } 
    cursor.close(); 
    db.close(); 
    // return score array 
    return data; 
} 
} 

这里是类我希望当我打开的页面与高的分数，在应用程序来控制从

public class highscores extends Activity {  

private ListView scorebox; 

@Override 
protected void onCreate(Bundle savedInstanceState) { 
    DBHandler db = new DBHandler(this); 
    scorebox = (ListView) findViewById(R.id.scorebox); 
    super.onCreate(savedInstanceState); 
    setContentView(R.layout.highscores); 
    Log.d("Insert: ", "Inserting .."); 
    db.addScore(9000); 
    Log.d("Reading: ", "Reading all contacts.."); 
} 
} 

数据库 - 它是空白，如何让它显示的东西，我想用这个命令db.addScore(9000);但它不工作。也许我没有告诉数据库在哪里显示数据？

Answer 1

编辑高分类

public class highscores extends Activity {  
    private ListView scorebox; 
@Override 
protected void onCreate(Bundle savedInstanceState) { 
    super.onCreate(savedInstanceState); 
    setContentView(R.layout.highscores); 
    DBHandler db = new DBHandler(this); 
    scorebox = (ListView) findViewById(R.id.scorebox); 
    Log.d("Insert: ", "Inserting .."); 
    db.addScore(9000); 
    Log.d("Reading: ", "Reading all contacts.."); 
    ArrayList<String>ar=new ArrayList<>(); 
    ar=db.getAllScores(); 
    ArrayAdapter<String>ar=new ArrayAdapter<String>(this,android.R.layout.simple_list_item_1,s); 
    scorebox.setAdapter(ar); 
} 
} 

现在你DBHandler类编辑getAllScores（）方法像这样

public ArrayList getAllScores() { 

// Select All Query 
String selectQuery = "SELECT * FROM " + TABLE_DETAIL; 

SQLiteDatabase db = this.getWritableDatabase(); 
Cursor cursor = db.rawQuery(selectQuery, null); 

// looping through all rows and adding to list 


ArrayList<String>data=new ArrayList<>(); 

while (cursor.moveToNext()) { 

    data.add(cursor.getString(1)); 


} 
cursor.close(); 
db.close(); 
// return score array 
return data; 
} 

Answer 2

如果你正在使用模拟器，你可以拉数据库文件，并检查是否创建该表与否，如果您使用的设备，您可以使用此命令

CD/DD：\的Android \ SDK \平台-tools // Android SDK中路径

ADB -d壳

运行作为com.pkg.pkgname

猫/data/data/com.pkg.pkgname/databases/highscores>/SD卡/高分

它会将你的数据库文件复制到设备的SD卡。使用Sqlite browser你可以打开数据库文件并检查表是否被创建。 也将卸载应用程序，并重新安装

Answer 3

使用此列出你的分数在你的列表视图

public class highscores extends Activity {  

    private ListView scorebox; 

    @Override 
    protected void onCreate(Bundle savedInstanceState) { 
     super.onCreate(savedInstanceState); 
     setContentView(R.layout.highscores); 
     DBHandler db = new DBHandler(this); 
     scorebox = (ListView) findViewById(R.id.scorebox); 
     Log.d("Insert: ", "Inserting .."); 
     db.addScore(9000); 
     Log.d("Reading: ", "Reading all contacts.."); 
     String []s=db.getAllScores(); 
     ArrayAdapter<String>ar=new ArrayAdapter<String>(this,android.R.layout.simple_list_item_1,s); 
     scorebox.setAdapter(ar); 
    } 
    }