Question

这是一个测验应用程序得分将添加到Rank表中，还有一个按钮，通过点击它将表中的分数将被删除..但我工作正常前两次现在它继续崩溃。没有我之前第一次遇到这个错误因为我从begining开始编码。错误在

之下

致命的例外：主要 java.lang.RuntimeException：无法启动活动ComponentInfo {com.example.kdeepti.navyquiz / com.example.kdeepti.navyquiz.Score}：android.database.sqlite.SQLiteException：no such table：Rank（code 1）:,编译时：SELECT * FROM Rank按分数排序DESC LIMIT 10;

表存在于数据库中，我也尝试过SQLiteAssestHelper 我的活动

公共类MainActivity扩展了AppCompatActivity {

Button btnPlay,btnScore, btnExit;
TextView textView;
ImageButton btnShare,info,clear;

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);
    info =(ImageButton) findViewById(R.id.info);
    btnPlay = (Button) findViewById(R.id.btnPlay);
    btnScore = (Button) findViewById(R.id.btnScore);
    btnExit = (Button) findViewById(R.id.btnExit);
    textView =(TextView) findViewById(R.id.textView);
    textView.setText("Main");

    clear =(ImageButton) findViewById(R.id.clear);

    btnShare=(ImageButton) findViewById(R.id.btnShare);

    btnPlay.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {
            Intent intent = new Intent(getApplicationContext(), CategorySecond.class);
            startActivity(intent);
            overridePendingTransition(R.anim.fade_in, R.anim.fade_out);
            finish();
        }
    });

    btnScore.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {
            Intent intent = new Intent(getApplicationContext(), Score.class);
            startActivity(intent);
            overridePendingTransition(R.anim.push_in, R.anim.push_out);
            finish();
        }
    });

    btnExit.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {
            Intent intent = new Intent(getApplicationContext(), Instruction.class);
            startActivity(intent);
            overridePendingTransition(R.anim.zoom_in, R.anim.zoom_out);
            finish();

        }
    });

    info.setOnClickListener(new View.OnClickListener(){
        @Override
        public void onClick(View v) {
            Intent intent = new Intent(getApplicationContext(), About.class);
            startActivity(intent);
            overridePendingTransition(R.anim.slide_up, R.anim.slide_down);
            finish();
        }
    });

    btnShare.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {
            Intent intent = new Intent(Intent.ACTION_SEND);
            intent.setType("text/plain");
            intent.putExtra(Intent.EXTRA_SUBJECT,"My New App");
            String applink="Hello,Welcome to NavyQuiz";
            intent.putExtra(Intent.EXTRA_TEXT,"Try My new App :"+applink);
            startActivity(Intent.createChooser(intent,"Share Via"));
        }
    });

    final DbHelper db=new DbHelper(this);
    clear.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {                
            db.deleteTable();      

        }
    });
}

}

我的DbHelper代码

public class DbHelper extends SQLiteOpenHelper {

private static String DB_NAME = "QuizDb14.db";
private static String DB_PATH = "";
private SQLiteDatabase mDataBase;
private Context mContext = null;

public DbHelper(Context context) {
    super(context, DB_NAME, null, 1);

    DB_PATH = context.getApplicationInfo().dataDir + "/databases/";
    File file = new File(DB_PATH+"QuizDb14.db");
    if(file.exists())
        openDataBase(); // Add this line to fix db.insert can't insert values
    this.mContext = context;
}

public void openDataBase() {
    String myPath = DB_PATH + DB_NAME;
    mDataBase = SQLiteDatabase.openDatabase(myPath, null, SQLiteDatabase.OPEN_READWRITE);
}

public void copyDataBase() throws IOException {
    try {
        InputStream myInput = mContext.getAssets().open(DB_NAME);
        String outputFileName = DB_PATH + DB_NAME;
        OutputStream myOutput = new FileOutputStream(outputFileName);

        byte[] buffer = new byte[1024];
        int length;
        while ((length = myInput.read(buffer)) > 0)
            myOutput.write(buffer, 0, length);

        myOutput.flush();
        myOutput.close();
        myInput.close();
    } catch (Exception e) {
        e.printStackTrace();
    }
}

private boolean checkDataBase() {
    SQLiteDatabase tempDB = null;
    try {
        String myPath = DB_PATH + DB_NAME;
        tempDB = SQLiteDatabase.openDatabase(myPath, null, SQLiteDatabase.OPEN_READWRITE);
    } catch (SQLiteException e) {
        e.printStackTrace();
    }
    if (tempDB != null)
        tempDB.close();
    return tempDB != null ? true : false;
}

public void createDataBase() throws IOException {
    boolean isDBExists = checkDataBase();
    if (isDBExists) {

    } else {
        this.getReadableDatabase();
        try {
            copyDataBase();
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
}



@Override
public void onCreate(SQLiteDatabase db) {

}

@Override
public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {

}
 public void insertScore(int score) {
    openDataBase();
    String query = "INSERT INTO Rank(Score) VALUES(" + score + ")";
    mDataBase.execSQL(query);
    mDataBase.close();
}




public List<Rank> getRanking() {
    List<Rank> listRanking = new ArrayList<>();
    SQLiteDatabase db = this.getReadableDatabase();
    Cursor c = db.rawQuery("SELECT * FROM Rank Order By Score DESC LIMIT 10;", null);
    try {

        if (c == null) return null;
        c.moveToNext();
        do {
            int Id = c.getInt(c.getColumnIndex("ID"));
            int Score = c.getInt(c.getColumnIndex("Score"));


            Rank ranking = new Rank(Id, Score);
            listRanking.add(ranking);
        } while (c.moveToNext());

    } catch (Exception e) {
        e.printStackTrace();
    }
    finally {
        c.close();
        db.close();
    }
    return listRanking;

}

public void deleteTable() {
    SQLiteDatabase db = this.getWritableDatabase(); // helper is object extends SQLiteOpenHelper
    db.execSQL("DELETE FROM Rank");
    db.close();
}

Answer 1

您需要使用一些数据库调试工具来查找确切的问题。 Stetho是来自facebook的优秀图书馆，可以帮助您在运行时查看数据库。您可以按照此处的步骤实现它 - http://facebook.github.io/stetho/

让我们知道您是否面临实施此问题的挑战。

表存在于数据库中仍然显示没有这样的表

1 个答案: