我有下面这个方法，它从sqlite数据库中提取随机问题，从名为tblPitanja的tbale（db中有3个表）和四个可能的答案。在用户回答问题后，我现在需要从相同的sqlite数据库中提取问题和答案，但是来自不同的表。我需要问一些与上一个问题相关的补充问题。怎么做？现在最困难的部分是如何知道上一个问题中的ID。
private void nextQuestion() {
counter++;
TestAdapter mDbHelper = new TestAdapter(this);
mDbHelper.createDatabase();
try{
mDbHelper.open();
Cursor c = mDbHelper.getTestData(generateWhereClause());
mAnsweredQuestions.add(c.getLong(0));
List<Answer> labels = new ArrayList<Answer>();
labels.add(new Answer(c.getString(2), true));
labels.add(new Answer(c.getString(3), false));
labels.add(new Answer(c.getString(4), false));
labels.add(new Answer(c.getString(5), false));
tacanOdg = c.getString(2);
Collections.shuffle(labels);
byte[] image_bytes = c.getBlob(c.getColumnIndex("PITANJE"));
ByteArrayInputStream inputStream = new ByteArrayInputStream(image_bytes);
Bitmap bp=BitmapFactory.decodeStream(inputStream);
if(counter < 11){
flag.setImageBitmap(bp);
bOdgovor1.setText(labels.get(0).option);
bOdgovor1.setTag(labels.get(0));
bOdgovor1.setOnClickListener(clickListener);
bOdgovor2.setText(labels.get(1).option);
bOdgovor2.setTag(labels.get(1));
bOdgovor2.setOnClickListener(clickListener);
bOdgovor3.setText(labels.get(2).option);
bOdgovor3.setTag(labels.get(2));
bOdgovor3.setOnClickListener(clickListener);
bOdgovor4.setText(labels.get(3).option);
bOdgovor4.setTag(labels.get(3));
bOdgovor4.setOnClickListener(clickListener);
rezultat.setText(counter + "/10");
score.setText("Score: " + brojacTacnihOdgovora);
}else{
brojacVremena.cancel();
}
}
finally{
mDbHelper.close();
}
编辑：
数据库助手：
public class DataBaseHelper extends SQLiteOpenHelper
{
private static String TAG = "DataBaseHelper"; // Tag just for the LogCat window
//destination path (location) of our database on device
private static String DB_PATH = "/data/data/rs.androidaplikacije.flags/databases/";
private static String DB_NAME ="pitanja.sqlite";// Database name
private static SQLiteDatabase mDataBase;
private final Context mContext;
public DataBaseHelper(Context mojContext)
{
super(mojContext, DB_NAME, null, 1);// 1? its Database Version
DB_PATH = mojContext.getApplicationInfo().dataDir + "/databases/";
this.mContext = mojContext;
}
public void createDataBase() throws IOException
{
//If database not exists copy it from the assets
this.getReadableDatabase();
this.close();
try
{
//Copy the database from assests
copyDataBase();
Log.e(TAG, "createDatabase database created");
}
catch (IOException mIOException)
{
throw new Error("ErrorCopyingDataBase");
}
}
/*Check that the database exists here: /data/data/your package/databases/Da Name
private boolean checkDataBase()
{
File dbFile = new File(DB_PATH + DB_NAME);
//Log.v("dbFile", dbFile + " "+ dbFile.exists());
return dbFile.exists();
}
*/
//Copy the database from assets
private void copyDataBase() throws IOException
{
InputStream mInput = mContext.getAssets().open(DB_NAME);
String outFileName = DB_PATH + DB_NAME;
OutputStream mOutput = new FileOutputStream(outFileName);
byte[] mBuffer = new byte[1024];
int mLength;
while ((mLength = mInput.read(mBuffer))>0)
{
mOutput.write(mBuffer, 0, mLength);
}
mOutput.flush();
mOutput.close();
mInput.close();
}
//Open the database, so we can query it
public boolean openDataBase() throws SQLException
{
String mPath = DB_PATH + DB_NAME;
//Log.v("mPath", mPath);
mDataBase = SQLiteDatabase.openDatabase(mPath, null, SQLiteDatabase.CREATE_IF_NECESSARY);
//mDataBase = SQLiteDatabase.openDatabase(mPath, null, SQLiteDatabase.NO_LOCALIZED_COLLATORS);
return mDataBase != null;
}
@Override
public void close()
{
if(mDataBase != null)
mDataBase.close();
super.close();
}
@Override
public void onCreate(SQLiteDatabase arg0) {
}
@Override
public void onUpgrade(SQLiteDatabase arg0, int arg1, int arg2) {
Log.w("DataBaseHelper", "Upgrading database!!!!!");
onCreate(arg0);
}
}
适配器：
public class TestAdapter
{
protected static final String TAG = "DataAdapter";
private final Context mContext;
private SQLiteDatabase mDb;
private DataBaseHelper mDbHelper;
public TestAdapter(Context context)
{
this.mContext = context;
mDbHelper = new DataBaseHelper(mContext);
}
public TestAdapter createDatabase() throws SQLException
{
try
{
mDbHelper.createDataBase();
}
catch (IOException mIOException)
{
Log.e(TAG, mIOException.toString() + " UnableToCreateDatabase");
throw new Error("UnableToCreateDatabase");
}
return this;
}
public TestAdapter open() throws SQLException
{
try
{
mDbHelper.openDataBase();
mDbHelper.close();
mDb = mDbHelper.getReadableDatabase();
}
catch (SQLException mSQLException)
{
Log.e(TAG, "open >>"+ mSQLException.toString());
throw mSQLException;
}
return this;
}
public void close()
{
mDbHelper.close();
}
public Cursor getTestData(String whereClause)
{;
try
{
String sql ="SELECT * FROM tblPitanja WHERE 1 = 1 " + whereClause + " ORDER BY RANDOM() LIMIT 1";
Cursor mCur = mDb.rawQuery(sql, null);
if (mCur!=null)
{
mCur.moveToNext();
}
return mCur;
}
catch (SQLException mSQLException)
{
Log.e(TAG, "getTestData >>"+ mSQLException.toString());
throw mSQLException;
}
}
public Cursor getTestDataGradovi()
{;
try
{
String sql ="SELECT * FROM tblGradovi LIMIT 1";
Cursor mCur = mDb.rawQuery(sql, null);
if (mCur!=null)
{
mCur.moveToNext();
}
return mCur;
}
catch (SQLException mSQLException)
{
Log.e(TAG, "getTestData >>"+ mSQLException.toString());
throw mSQLException;
}
}
public Cursor getTestDataValute()
{;
try
{
String sql ="SELECT * FROM tblValute LIMIT 1";
Cursor mCur = mDb.rawQuery(sql, null);
if (mCur!=null)
{
mCur.moveToNext();
}
return mCur;
}
catch (SQLException mSQLException)
{
Log.e(TAG, "getTestData >>"+ mSQLException.toString());
throw mSQLException;
}
}
}
我的另一个问题的新方法（它尚未完成，它只是复制了我的第一个方法，并进行了一些更改，以便从db adapter类使用.getTestDataGradovi（）：
private void nextQuestionGrad() {
flag.setVisibility(View.GONE);
dodatnoPitanje.setVisibility(View.VISIBLE);
TestAdapter mDbHelper = new TestAdapter(this);
mDbHelper.createDatabase();
try{
mDbHelper.open();
Cursor c = mDbHelper.getTestDataGradovi();
mAnsweredQuestions.add(c.getLong(0));
List<Answer> labels = new ArrayList<Answer>();
labels.add(new Answer(c.getString(2), true));
labels.add(new Answer(c.getString(3), false));
labels.add(new Answer(c.getString(4), false));
labels.add(new Answer(c.getString(5), false));
tacanOdg = c.getString(2);
Collections.shuffle(labels);
dodatnoPitanje.setText(c.getString(1));
bOdgovor1.setText(labels.get(0).option);
bOdgovor1.setTag(labels.get(0));
bOdgovor1.setOnClickListener(clickListenerGrad);
bOdgovor2.setText(labels.get(1).option);
bOdgovor2.setTag(labels.get(1));
bOdgovor2.setOnClickListener(clickListenerGrad);
bOdgovor3.setText(labels.get(2).option);
bOdgovor3.setTag(labels.get(2));
bOdgovor3.setOnClickListener(clickListenerGrad);
bOdgovor4.setText(labels.get(3).option);
bOdgovor4.setTag(labels.get(3));
bOdgovor4.setOnClickListener(clickListenerGrad);
score.setText("Score: " + brojacTacnihOdgovora);
}
}
finally{
mDbHelper.close();
}
}
答案 0 :(得分：0)
您需要更改getTestDataGradovi以加载一个由其ID标识的特定记录：
public Cursor getTestDataGradovi(long id) {
String sql = "SELECT * FROM tblGradovi WHERE _ID = " + id;
Cursor c = mDb.rawQuery(sql, null);
c.moveToNext();
return c;
}
在nextQuestion内，你需要在某处保存当前问题的ID：
mCurrentID = c.GetLong(0);
在nextQuestionGrad内，您可以使用保存的ID来获取相应的其他问题：
Cursor c = mDbHelper.getTestDataGradovi(mCurrentID);