Diese Frage hat hier bereits eine Antwort:

Ich möchte eine Anwendung entwickeln, in der ich SQLite-Datenbank in Android verwenden muss. Nachfolgend sehen Sie den Code, der die Datenbank und alle von meiner Anwendung benötigten Operationen mit zufälligen Daten implementiert (nur um die Logik zuerst erfolgreich zu implementieren).

Dieser Code ist in DBHelperDisplay.java geschrieben, das von MainActivity.java absichtlich aufgerufen wird.

Meine DBHelperDisplay.java:

package course.examples.jumboquest;

import java.util.Random;
import android.support.v7.app.ActionBarActivity;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;
//import android.widget.EditText;
import android.widget.RadioButton;
import android.widget.RadioGroup;
import android.widget.TextView;
//import android.content.Intent;
import android.os.CountDownTimer;
import android.content.ContentValues;
import android.content.Context;
import android.database.Cursor;
import android.database.DatabaseUtils;
import android.database.sqlite.SQLiteOpenHelper;
import android.database.sqlite.SQLiteDatabase;

public class DBHelperDisplay extends ActionBarActivity {

TextView tv; 
DBHelper myDB;
RadioGroup radioChoices;
RadioButton rbtChoice; 
Button btSubmit;
String choice1;
String choice2;
String choice3;
String choice4;
String strAns;
CustomTimer cdt;

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.dbhelper_display);

    cdt = new CustomTimer(20000, 1000);
    cdt.start();

    myDB = new DBHelper(this);

    myDB.insertQuestion(1, "who is the team member whose name starts with s?", "Vinita", "Akanksha", "Swati", "Megha", "Swati");
    myDB.insertQuestion(2, "who is the team member whose name starts with m?", "Vinita", "Akanksha", "Swati", "Megha", "Megha");
    myDB.insertQuestion(3, "who is the team member whose name starts with a?", "Vinita", "Akanksha", "Swati", "Megha", "Akanksha");
    myDB.insertQuestion(4, "who is the team member whose name starts with v?", "Vinita", "Akanksha", "Swati", "Megha", "Vinita");
    myDB.insertQuestion(5, "who is the team member whose name ends with i?", "Vinita", "Akanksha", "Swati", "Megha", "Swati");

    Cursor rs = myDB.getData();
    String Question = rs.getString(rs.getColumnIndex(DBHelper.Col_Ques));
    choice1 = rs.getString(rs.getColumnIndex(DBHelper.Col_Choice1));
    choice2 = rs.getString(rs.getColumnIndex(DBHelper.Col_Choice2));
    choice3 = rs.getString(rs.getColumnIndex(DBHelper.Col_Choice3));
    choice4 = rs.getString(rs.getColumnIndex(DBHelper.Col_Choice4));
    strAns = rs.getString(rs.getColumnIndex(DBHelper.Col_Ans));


    tv = (TextView) findViewById(R.id.timertxt);

    final TextView quest = (TextView) findViewById(R.id.quest);
    quest.setText(Question);

    //final TextView ans = (TextView) findViewById(R.id.ans);

    Button btClear = (Button)findViewById(R.id.btClear);
    btClear.setText("CLEAR");

   addListenerRadioChoices() ;

   btClear.setOnClickListener(new View.OnClickListener(){
     public void onClick(View v) {
        //ans.setText("");

       }
  });
 }
    public void addListenerRadioChoices(){ 

    radioChoices = (RadioGroup) findViewById(R.id.radioChoices);

    ((RadioButton) radioChoices.getChildAt(0)).setText(choice1); 
    ((RadioButton) radioChoices.getChildAt(1)).setText(choice2);
    ((RadioButton) radioChoices.getChildAt(2)).setText(choice3);
    ((RadioButton) radioChoices.getChildAt(3)).setText(choice4);

    btSubmit = (Button)findViewById(R.id.btSubmit); 
    btSubmit.setText("SUBMIT");
    btSubmit.setOnClickListener(new View.OnClickListener(){
     public void onClick(View v) {

        int selected = radioChoices.getCheckedRadioButtonId();
        rbtChoice = (RadioButton) findViewById(selected); 
        String Ans = rbtChoice.getText().toString();
         if(Ans.equalsIgnoreCase(strAns)){

            cdt.cancel();
            //ans.setText(" ANSWER");

         }
        /* else{
            //  ans.setText("WRONG ANSWER");
         }*/

    }
   });
  } 

public class CustomTimer extends CountDownTimer{
    //TextView ed;
    public CustomTimer(long millisInFuture, long countDownInterval){
        super(millisInFuture, countDownInterval);
    }
    @Override
    public void onTick(long millisUntilFinished){
        //current = millisUntilFinished/1000;
        tv.setText("Time Left:" + millisUntilFinished/1000);
    }
    @Override
    public void onFinish() {
        tv.setText("Time Up - lost the game!");
    }
}

public class DBHelper extends SQLiteOpenHelper {

    public static final String Database_Name = "Questions.db"; 
    public static final String Table_Name = "Comics"; 
    public static final String Col_ID = "id"; 
    public static final String Col_Ques = "question"; 
    public static final String Col_Choice1 = "choice1"; 
    public static final String Col_Choice2 = "choice2"; 
    public static final String Col_Choice3 = "choice3"; 
    public static final String Col_Choice4 = "choice4"; 
    public static final String Col_Ans = "answer"; 

    public DBHelper(Context context){
        super(context, Database_Name, null, 1);
    }
    @Override 
    public void onCreate(SQLiteDatabase db){
        // TODO Auto-generated method stub  
       db.execSQL(
       "CREATE TABLE Comics" +
       "(id integer primary key, question text, choice1 text, choice2 text, choice3 text, choice4 text, answer text)");

    }   
    @Override
    public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
          // TODO Auto-generated method stub
          db.execSQL("DROP TABLE IF EXISTS Comics");
          onCreate(db);
    }

    public boolean insertQuestion(int id, String question, String choice1, String choice2, String choice3, String choice4, String answer){
        SQLiteDatabase db = this.getWritableDatabase();
        ContentValues contentValues = new ContentValues();

        contentValues.put("id",id);
        contentValues.put("question",question);
        contentValues.put("choice1",choice1);
        contentValues.put("choice2",choice2);
        contentValues.put("choice3",choice3);
        contentValues.put("choice4",choice4);
        contentValues.put("answer",answer);
        db.insert("Comics", null, contentValues);
        db.close();
        return true;
    }
    public Cursor getData(){
        SQLiteDatabase db = this.getReadableDatabase();
        int numRows = (int)DatabaseUtils.queryNumEntries(db,Table_Name);
        int min = 1;
        int max = numRows;
        Random r = new Random();
        int id = r.nextInt(max - min + 1) + min;
        Cursor res= db.rawQuery("Select * from Comics where id = " + id + "", null);
        return res;
    }
}

}

Meine AndroidManifest.xml-Datei:

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="course.examples.jumboquest"
android:versionCode="1"
android:versionName="1.0" >

<uses-sdk
    android:minSdkVersion="8"
    android:targetSdkVersion="21" />

<application
    android:allowBackup="true"
    android:icon="@drawable/ic_launcher"
    android:label="@string/app_name"
    android:theme="@style/AppTheme" >
    <activity
        android:name=".MainActivity"
        android:label="@string/app_name" >
        <intent-filter>
            <action android:name="android.intent.action.MAIN" />

            <category android:name="android.intent.category.LAUNCHER" />
        </intent-filter>
    </activity>
    <activity android:name=".DBHelperDisplay"></activity>
</application>

</manifest>

Beim Ausführen des obigen Codes wird der folgende Fehler angezeigt:

Ich habe viel gesucht und viele Stapelüberlauf-Links mit dem gleichen Problem gefunden, aber es ist immer noch nicht behoben. Ich bin neu in diesem Thema. Bitte hilf mir