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我是Android新手。我試圖通過getDataMain（）方法從數據庫獲取數據。當我運行我的應用程序時，它會給出java.lang.NullPointerException。我找不到問題在哪裏？請問你能幫幫我嗎？訪問android中的數據庫時SQLite類的java.lang.NullPointerException異常
@TargetApi(Build.VERSION_CODES.HONEYCOMB)
public class MainFragment extends Fragment {
TextView bakici;
TextView arabaKredisi;
TextView ogrenimKredisi;
TextView tatilKredisi;
TextView elektrik;
TextView su;
TextView internet;
TextView aidat;
TextView kasko;
TextView digerTaksitler;
TextView diger;
TextView maasSelo;
TextView maasHilal;
TextView digerGelirler;
TextView toplamGelir;
TextView toplamHarcama;
TextView eldeKalan;
private final String TAG = this.getClass().getSimpleName();
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
Log.i(TAG, "mainFragmentonCreate");
}
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
View view = inflater.inflate(R.layout.maingetirgoster,
container, false);
toplamGelir = (TextView) view.findViewById(R.id.textToplamGelir2);
digerGelirler = (TextView) view.findViewById(R.id.textDigerGelirler2);
toplamHarcama = (TextView) view.findViewById(R.id.textToplamHarcama2);
diger = (TextView) view.findViewById(R.id.textDiger2);
digerTaksitler = (TextView) view.findViewById(R.id.textDigerTaksitler2);
kasko = (TextView) view.findViewById(R.id.textKaskoSigorta2);
aidat = (TextView) view.findViewById(R.id.textAidat2);
internet = (TextView) view.findViewById(R.id.textFaturaInternet2);
su = (TextView) view.findViewById(R.id.textFaturaSu2);
elektrik = (TextView) view.findViewById(R.id.textFaturaElektrik2);
tatilKredisi = (TextView) view.findViewById(R.id.textTatilKredisi2);
ogrenimKredisi = (TextView)view.findViewById(R.id.textOgrenimKredisi2);
arabaKredisi = (TextView) view.findViewById(R.id.textKrediAraba2);
bakici = (TextView) view.findViewById(R.id.textButtonBakici2);
eldeKalan = (TextView) view.findViewById(R.id.textEldeKalan2);
maasSelo = (TextView) view.findViewById(R.id.textMaasSelo2);
maasHilal = (TextView) view.findViewById(R.id.textMaasHilal2);
Context context=getActivity();
TemporaryDatabase tdb= new TemporaryDatabase(context);
tdb.open();
String[] result2= new String[2];
result2=tdb.getData();
tdb.close();
AySonuDatabase adb=new AySonuDatabase(context);
adb.open();
String result[]= new String[25];
**line:49** result = adb.getDataMain(Integer.getInteger(result2[0]), result2[1]);
adb.close();
bakici.setText(result[2]);
arabaKredisi.setText(result[3]);
ogrenimKredisi.setText(result[4]);
tatilKredisi.setText(result[5]);
elektrik.setText(result[6]);
su.setText(result[7]);
internet.setText(result[8]);
aidat.setText(result[9]);
kasko.setText(result[10]);
digerTaksitler.setText(result[11]);
diger.setText(result[12]);
maasSelo.setText(result[13]);
maasHilal.setText(result[14]);
digerGelirler.setText(result[15]);
toplamHarcama.setText(result[16]);
toplamGelir.setText(result[17]);
eldeKalan.setText(result[18]);
Log.i(TAG, "mainFragmentonCreateView");
return view;
}
@Override
public void onActivityCreated(Bundle savedInstanceState) {
// TODO Auto-generated method stub
super.onActivityCreated(savedInstanceState);
}
}
和這裏是數據庫類：
public class AySonuDatabase {
public static final String TAG = DatabaseHelper.class.getSimpleName();
public static final String DB_NAME = "butcedb.sql";
private static String DB_PATH ="/data/data/com.bilge.aysonu/assets/";
public static final int DB_VERSION = 1;
public static final String DB_TABLE = "harcamalar";
public static final String C_ID = "c_id";// Special for id
public static final String C_YIL = "spinnerYillar";
public static final String C_AY = "spinnerAylar";
public static final String C_BAKICI = "editTextBakici";
public static final String C_KREDIARABA = "editTextKrediAraba";
public static final String C_KREDIOGRENIM = "editTextKrediOgrenim";
public static final String C_KREDITATIL = "editTextKrediTatil";
public static final String C_FATURAELEKTRIK = "editTextFaturaElektrik";
public static final String C_FATURASU = "editTextFaturaSu";
public static final String C_FATURAINTERNET = "editTextFaturaInternet";
public static final String C_AIDAT = "editTextAidat";
public static final String C_KASKOSIGORTA = "editTextKaskoSigorta";
public static final String C_DIGERTAKSITLER = "editTextDigerTaksitler";
public static final String C_DIGER = "editTextDiger";
public static final String C_MAASSELO = "editTextMaasSelo";
public static final String C_MAASHILAL = "editTextMaasHilal";
public static final String C_DIGERGELIRLER = "editTextDigerGelirler";
public static final String C_TOPLAMHARCAMA = "editTextToplamHarcama";
public static final String C_TOPLAMGELIR = "editTextToplamGelir";
public static final String C_ELDEKALAN = "editTextEldeKalan";
public static final String CREATE_TABLE="CREATE TABLE harcamalar (c_id integer primary key autoincrement," +
"spinnerYillar integer,spinnerAylar TEXT,editTextBakici integer,editTextKrediAraba integer,editTextKrediOgrenim integer,editTextKrediTatil integer," +
"editTextFaturaElektrik integer,editTextFaturaSu integer,editTextFaturaInternet integer,editTextAidat integer,editTextKaskoSigorta integer," +
"editTextDigerTaksitler integer,editTextDiger integer,editTextMaasSelo integer,editTextMaasHilal integer,editTextDigerGelirler integer," +
"editTextToplamHarcama integer,editTextToplamGelir integer, editTextEldeKalan integer);";
private DatabaseHelper dbHelper;
private final Context ourContext;
private SQLiteDatabase ourDatabase;
public static class DatabaseHelper extends SQLiteOpenHelper {
public DatabaseHelper(Context context) {
super(context, DB_NAME, null, DB_VERSION);
}
@Override
public void onCreate(SQLiteDatabase db) {
Log.d(TAG, "onCreate sql: " + CREATE_TABLE);
db.execSQL(CREATE_TABLE);
}
@Override
public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
db.execSQL("drop table if exists " + DB_TABLE);
Log.w(TAG, "onUpdate drop table " + DB_TABLE);
onCreate(db);
}
}
public AySonuDatabase(Context c) {
ourContext = c;
}
public void openDatabase() throws SQLException {
ourDatabase = SQLiteDatabase.openDatabase(DB_PATH + DB_NAME, null,
SQLiteDatabase.OPEN_READWRITE);
}
public void open() throws NumberFormatException {
try{
dbHelper = new DatabaseHelper(ourContext);
ourDatabase = dbHelper.getWritableDatabase();
return ;
} catch (Exception e) {
Log.d(TAG,"Couldn't open database "+DB_NAME);
e.printStackTrace();
}
}
public void close() {
dbHelper.close();
ourDatabase.close();
}
public void Entry(int yilsql, String aysql, int bakicisql,
int krediArabasql, int krediOgrenimsql, int krediTatilsql,
int faturaElektriksql, int faturaSusql, int faturaInternetsql,
int aidatsql, int kaskoSigortasql, int digerTaksitlersql,
int digersql, int maasSelosql,int maasHilalsql,int digerGelirlersql,
int toplamHarcamasql,int toplamGelirsql,int eldeKalansql) {
ContentValues cv = new ContentValues();
cv.put(C_YIL, yilsql);
cv.put(C_AY, aysql);
cv.put(C_BAKICI, bakicisql);
cv.put(C_KREDIARABA, krediArabasql);
cv.put(C_KREDIOGRENIM, krediOgrenimsql);
cv.put(C_KREDITATIL, krediTatilsql);
cv.put(C_FATURAELEKTRIK, faturaElektriksql);
cv.put(C_FATURASU, faturaSusql);
cv.put(C_FATURAINTERNET, faturaInternetsql);
cv.put(C_AIDAT, aidatsql);
cv.put(C_KASKOSIGORTA, kaskoSigortasql);
cv.put(C_DIGERTAKSITLER, digerTaksitlersql);
cv.put(C_DIGER, digersql);
cv.put(C_MAASSELO,maasSelosql);
cv.put(C_MAASHILAL, maasHilalsql);
cv.put(C_DIGERGELIRLER, digerGelirlersql);
cv.put(C_TOPLAMHARCAMA,toplamHarcamasql);
cv.put(C_TOPLAMGELIR, toplamGelirsql);
cv.put(C_ELDEKALAN, eldeKalansql);
String[] selectionArgs=new String[]{yilsql+"", aysql};
String entryGirisSQL="SELECT c_id FROM harcamalar WHERE "+C_YIL+"= ? AND "+C_AY+"= ?";
Cursor cursor=ourDatabase.rawQuery(entryGirisSQL, selectionArgs);
cursor.moveToFirst();
int index=cursor.getInt(cursor.getColumnIndex(C_ID));
if(cursor.isNull(cursor.getColumnIndex(C_ID)))
ourDatabase.insert(DB_TABLE, null, cv);
else
ourDatabase.update(DB_TABLE, cv, C_ID+"="+index, null);
cursor.close();
}
保護字符串[] getDataMain（INT yilsql，字符串aysql）{ 字符串結果[] =新的String [25];
String[] selectionArgs=new String[]{yilsql+"", aysql};
String entryHesaplaSQL="SELECT * FROM harcamalar WHERE "+C_YIL+"= ? AND "+C_AY+"= ?";
Cursor c=ourDatabase.rawQuery(entryHesaplaSQL, selectionArgs);
if(c.moveToFirst()){
int i_yil = c.getColumnIndex(C_YIL);
int i_ay = c.getColumnIndex(C_AY);
int i_bakici = c.getColumnIndex(C_BAKICI);
int i_krediaraba = c.getColumnIndex(C_KREDIARABA);
int i_krediogrenim = c.getColumnIndex(C_KREDIOGRENIM);
int i_kreditatil = c.getColumnIndex(C_KREDITATIL);
int i_faturaelektrik = c.getColumnIndex(C_FATURAELEKTRIK);
int i_faturasu = c.getColumnIndex(C_FATURASU);
int i_faturainternet = c.getColumnIndex(C_FATURAINTERNET);
int i_aidat = c.getColumnIndex(C_AIDAT);
int i_kaskosigorta = c.getColumnIndex(C_KASKOSIGORTA);
int i_digertaksitler=c.getColumnIndex(C_DIGERTAKSITLER);
int i_diger=c.getColumnIndex(C_DIGER);
int i_maasselo=c.getColumnIndex(C_MAASSELO);
int i_maashilal=c.getColumnIndex(C_MAASHILAL);
int i_digergelirler=c.getColumnIndex(C_DIGERGELIRLER);
int i_toplamharcama=c.getColumnIndex(C_TOPLAMHARCAMA);
int i_toplamgelir=c.getColumnIndex(C_TOPLAMGELIR);
int i_eldekalan=c.getColumnIndex(C_ELDEKALAN);
result[0]=c.getString(i_yil);
result[1]=c.getString(i_ay);
result[2]=c.getString(i_bakici);
result[3]=c.getString(i_krediaraba);
result[4]=c.getString(i_krediogrenim);
result[5]=c.getString(i_kreditatil);
result[6]=c.getString(i_faturaelektrik);
result[7]=c.getString(i_faturasu);
result[8]=c.getString(i_faturainternet);
result[9]=c.getString(i_aidat);
result[10]=c.getString(i_kaskosigorta);
result[11]=c.getString(i_digertaksitler);
result[12]=c.getString(i_diger);
result[13]=c.getString(i_maasselo);
result[14]=c.getString(i_maashilal);
result[15]=c.getString(i_digergelirler);
result[16]=c.getString(i_toplamharcama);
result[17]=c.getString(i_toplamgelir);
result[18]=c.getString(i_eldekalan);
c.close();
return result;
} else{
final String string1= "No data!";
for(int i=2;i<19;i++)
result[i]=string1;
return result;
}
}
}
這裏是整個類的getData（）方法：
public class TemporaryDatabase {
public static final String TAG = DbHelperTemporary.class.getSimpleName();
public static final String DB_NAME = "aySonuTepmDB.sql";
private static String DB_PATH ="/data/data/com.bilge.aysonu/assets/";
public static final int DB_VERSION = 1;
public static final String DB_TABLE = "ayyil";
public static final String C_ID = "c_id";// Special for id
public static final String C_YIL = "spinnerYillar";
public static final String C_AY = "spinnerAylar";
public static final String CREATE_TABLE="CREATE TABLE ayyil (c_id integer primary key autoincrement," +
"spinnerYillar integer,spinnerAylar TEXT);";
private DbHelperTemporary dbHelper;
private final Context ourContext;
private SQLiteDatabase ourDatabase;
public static class DbHelperTemporary extends SQLiteOpenHelper {
public DbHelperTemporary(Context context) {
super(context, DB_NAME, null, DB_VERSION);
}
@Override
public void onCreate(SQLiteDatabase db) {
Log.d(TAG, "onCreate sql: " + CREATE_TABLE);
db.execSQL(CREATE_TABLE);
}
@Override
public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
db.execSQL("drop table if exists " + DB_TABLE);
Log.w(TAG, "onUpdate drop table " + DB_TABLE);
onCreate(db);
}
}
public TemporaryDatabase(Context c) {
ourContext = c;
}
public void openDatabase() throws SQLException {
ourDatabase = SQLiteDatabase.openDatabase(DB_PATH + DB_NAME, null,
SQLiteDatabase.OPEN_READWRITE);
}
public void open() throws NumberFormatException {
dbHelper = new DbHelperTemporary(ourContext);
ourDatabase = dbHelper.getWritableDatabase();
return ;
}
public void close() {
dbHelper.close();
ourDatabase.close();
}
public void Entry(int yilsql, String aysql) {
ContentValues cv = new ContentValues();
cv.put(C_YIL, yilsql);
cv.put(C_AY, aysql);
ourDatabase.delete(DB_TABLE, null, null);
ourDatabase.insert(DB_TABLE, null, cv);
cv.clear();
}
public String[] getData() {
String[] columns = new String[] { C_YIL, C_AY };
Cursor c = ourDatabase.query(DB_TABLE, null, null, null, null, null,null);
String[] result = new String[2];
int i_yil = c.getColumnIndex(C_YIL);
int i_ay = c.getColumnIndex(C_AY);
if (c.moveToFirst()) {
result[0]=c.getString(i_yil);
result[1]=c.getString(i_ay);
}
c.close();
return result;
}
}
這裏是例外：
I/MainFragment(1838): mainFragmentonCreate
D/AndroidRuntime(1838): Shutting down VM
W/dalvikvm(1838): threadid=1: thread exiting with uncaught exception (group=0xb3d87908)
E/AndroidRuntime(1838): FATAL EXCEPTION: main
E/AndroidRuntime(1838): java.lang.NullPointerException
E/AndroidRuntime(1838): at com.bilge.aysonu.MainFragment.onCreateView(MainFragment.java:49)
E/AndroidRuntime(1838):atandroid.support.v4.app.Fragment.performCreateView(Fragment.java:1460)
E/AndroidRuntime(1838): at android.support.v4.app.FragmentManagerImpl.moveToState(FragmentManager.java:911)
E/AndroidRuntime(1838): at android.support.v4.app.FragmentManagerImpl.moveToState(FragmentManager.java:1088)
E/AndroidRuntime(1838): at android.support.v4.app.BackStackRecord.run(BackStackRecord.java:682)
E/AndroidRuntime(1838): at android.support.v4.app.FragmentManagerImpl.execPendingActions(FragmentManager.java:1444)
E/AndroidRuntime(1838): at android.support.v4.app.FragmentManagerImpl$1.run(FragmentManager.java:429)
E/AndroidRuntime(1838): at android.os.Handler.handleCallback(Handler.java:725)
E/AndroidRuntime(1838): at android.os.Handler.dispatchMessage(Handler.java:92)
E/AndroidRuntime(1838): at android.os.Looper.loop(Looper.java:137)
E/AndroidRuntime(1838): at android.app.ActivityThread.main(ActivityThread.java:5039)
E/AndroidRuntime(1838): at java.lang.reflect.Method.invokeNative(Native Method)
E/AndroidRuntime(1838): at java.lang.reflect.Method.invoke(Method.java:511)
E/AndroidRuntime(1838): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:793)
E/AndroidRuntime(1838): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:560)
E/AndroidRuntime(1838): at dalvik.system.NativeStart.main(Native Method)
看起來像'tdb.getData（）'返回了空結果。我看不到它，很難調試。儘管如此，你應該很容易地使用調試器來弄清楚它。 –
對於數據庫操作，最好使用單獨的線程。 – hovanessyan
不，不是tdb.getData（），tdb.getDataMain（）返回null。 – hopeTo