向數據庫添加問題

Question

我想添加問題，選項，對數據庫的答案。我創建了具有5列的表格 id,QUESTION,OPTION 1,OPTION 2,OPTION 3和ANSWER。

基本上，我試圖創建一個測驗類型的遊戲，所以我想在我的表中存儲問題，選項和答案。爲此，我創建了：

• a Helperclass其中延伸SQLiteOpenHelper。具有構造函數需要5個參數即詢問，有三個選項和答案，並在
• 和Questions類我mainactivity.xml

我沒有太多的只是一個TextView來顯示一個問題和三個按鈕顯示選項。

我得到的數據庫停止錯誤，但我知道我非常接近，有一些小錯誤。

的logcat的窗口說：

---產生的原因：java.lang.IllegalStateException：getDatabase遞歸調用。

MainActivity.java

@Override 
protected void onCreate(Bundle savedInstanceState) { 
    super.onCreate(savedInstanceState); 
    setContentView(R.layout.activity_main); 
    helperclassAdapter = new HelperclassAdapter(this); 
    tv1 = (TextView) findViewById(R.id.labelquestion); 
    b1 = (Button) findViewById(R.id.opt1); 
    b2 = (Button) findViewById(R.id.opt2); 
    b3 = (Button) findViewById(R.id.opt3); 
    SQLiteDatabase sqLiteDatabase = helperclassAdapter.helperclass.getWritableDatabase(); 
} 

public void clickopt1(View view) { 

} 

public void clickopt2(View view) { 

} 

public void clickopt3(View view) { 

} 

HelperclassAdapter.java

public class HelperclassAdapter { 
Helperclass helperclass; 
Context context; 

public HelperclassAdapter(Context context) { 
    helperclass = new Helperclass(context); 
    this.context = context; 
} 
static public class Helperclass extends SQLiteOpenHelper { 
    //i added the SQLiteDatabase object over here and using this object  called insert method 
    SQLiteDatabase sqLiteDatabase; 
    Context context; 
    private static final String DATABASE_NAME = "DATABASE1"; 
    private static final int DATABASE_VERSION = 39; 
    private static final String TABLE_NAME = "TABLE1"; 
    private static final String UID = "_ID"; 
    private static final String QUESTION = "QUESTION"; 
    private static final String OPT1 = "OPT1"; 
    private static final String OPT2 = "OPT2"; 
    private static final String OPT3 = "OPT3"; 
    private static final String ANSWER = "ANSWER"; 
    private static final String CREATE_TABLE = 
      "CREATE TABLE " + TABLE_NAME + " (" + UID + " INTEGER PRIMARY KEY, " + QUESTION + " VARCHAR(255), " + OPT1 + " VARCHAR(255), " + OPT2 + " VARCHAR(255), " + OPT3 + " VARCHAR(255), " + ANSWER + " VARCHAR(255));"; 
    private static final String DROP_TABLE = "DROP TABLE IF EXISTS " + TABLE_NAME; 


    public Helperclass(Context context) { 
     super(context, DATABASE_NAME, null, DATABASE_VERSION); 
     this.context = context; 
     Toast.makeText(context, "constructor called", Toast.LENGTH_SHORT).show(); 
    } 

    @Override 
    public void onCreate(SQLiteDatabase sqLiteDatabase) { 
     try { 
      sqLiteDatabase.execSQL(CREATE_TABLE); 
      addquestions(); 
      Toast.makeText(context, "oncreate called", Toast.LENGTH_SHORT).show(); 
     } catch (SQLException e) { 
      e.printStackTrace(); 
      Toast.makeText(context, e.getMessage(), Toast.LENGTH_SHORT).show(); 
     } 
    } 

    @Override 
    public void onUpgrade(SQLiteDatabase sqLiteDatabase, int i, int i1) { 
     try { 
      Toast.makeText(context, "onupgrade called", Toast.LENGTH_SHORT).show(); 
      sqLiteDatabase.execSQL(DROP_TABLE); 
      onCreate(sqLiteDatabase); 
     } catch (SQLException e) { 
      e.printStackTrace(); 
      Toast.makeText(context, e.getMessage(), Toast.LENGTH_SHORT).show(); 
     } 
    } 
    public void addquestions() { 
     Questions q1 = new Questions("what is your hobby?", "singing", "dancing", "reading", "sining"); 
     this.addingeachquestions(q1); 
     Questions q2 = new Questions("how are you?", "fine", "good", "sad", "good"); 
     this.addingeachquestions(q2); 
     Questions q3 = new Questions("whats your name?", "sam", "jhon", "alice", "sam"); 
     this.addingeachquestions(q3); 
     Toast.makeText(context, "addquestion method called", Toast.LENGTH_SHORT).show(); 
    } 
    //BEFORE 
    private void addingeachquestions(Questions question) { 
     ContentValues values = new ContentValues(); 
     values.put(Helperclass.QUESTION, question.getQUESTION()); 
     values.put(Helperclass.OPT1, question.getOPTA()); 
     values.put(Helperclass.OPT2, question.getOPTB()); 
     values.put(Helperclass.OPT3, question.getOPTC()); 
     values.put(Helperclass.ANSWER, question.getANSWER()); 
     SQLiteDatabase db = getWritableDatabase(); 
     db.insert(Helperclass.TABLE_NAME, null, values); 
     Toast.makeText(context, "questions added", Toast.LENGTH_SHORT).show(); 
    } 
} 
    //AFTER 
    private void addingeachquestions(Questions question) { 
     ContentValues values = new ContentValues(); 
     values.put(Helperclass.QUESTION, question.getQUESTION()); 
     values.put(Helperclass.OPT1, question.getOPTA()); 
     values.put(Helperclass.OPT2, question.getOPTB()); 
     values.put(Helperclass.OPT3, question.getOPTC()); 
     values.put(Helperclass.ANSWER, question.getANSWER()); 
     sqLiteDatabase.insert(Helperclass.TABLE_NAME, null, values); 
     Toast.makeText(context, "questions added", Toast.LENGTH_SHORT).show(); 
    } 

Questions.java

public Questions() { 
    Question = ""; 
    Opt1 = ""; 
    Opt2 = ""; 
    Opt3 = ""; 
    Answer = ""; 
} 

public Questions(String qUESTION, String oPT1, String oPT2, String oPT3, 
       String aNSWER) { 
    Question = qUESTION; 
    Opt1 = oPT1; 
    Opt2 = oPT2; 
    Opt3 = oPT3; 

    Answer = aNSWER; 
} 

public String getQUESTION() { 
    return Question; 
} 

public String getOPTA() { 
    return Opt1; 
} 

public String getOPTB() { 
    return Opt2; 
} 

public String getOPTC() { 
    return Opt3; 
} 

public String getANSWER() { 
    return Answer; 
} 

Answer 1

1. 我會建議你使用ContentProvider來使用數據庫。如果你是先行者，它看起來很可怕，但你必須學習它！

內容提供商是一種適用於您和其他應用程序（如果您選擇）以正確方式訪問數據庫的方式。

ContentProvider documentation

我認爲馬力可變心不是intalized？

@Override 
public void onCreate(SQLiteDatabase sqLiteDatabase) { 
    try { 
     sqLiteDatabase.execSQL(CREATE_TABLE); 

// hp isnt intallized? 

     hp.addquestions(); 

     Toast.makeText(context, "oncreate called", Toast.LENGTH_SHORT).show(); 
    } catch (SQLException e) { 
     e.printStackTrace(); 
     Toast.makeText(context, e.getMessage(), Toast.LENGTH_SHORT).show(); 
    } 
} 

閱讀我的意見，再次讀到的ContentProvider！它非常重要，不僅適用於創建自己的數據庫，還適用於您與其他數據庫一起使用。 （如從庫獲取圖像）

private void addingeachquestions(Questions question) { 
 
     ContentValues values = new ContentValues(); 
 
     values.put(Helperclass.QUESTION, question.getQUESTION()); 
 
     values.put(Helperclass.OPT1, question.getOPTA()); 
 
     values.put(Helperclass.OPT2, question.getOPTB()); 
 
     values.put(Helperclass.OPT3, question.getOPTC()); 
 
     values.put(Helperclass.ANSWER, question.getANSWER()); 
 

 
//getWritableDatabase calls the onCreate() methos and the onCreate() method calls    addquestions(); which calls getWriteableDatabase. this is recrusive call, a method that makes infinity loop that crush your app. 
 
You should add the questions OUTSIDE the Helperclass. 
 

 
     SQLiteDatabase db = getWritableDatabase(); 
 
     db.insert(Helperclass.TABLE_NAME, null, values); 
 
     Toast.makeText(context, "questions added", Toast.LENGTH_SHORT).show(); 
 
    }