0
I have a problem that is seriously damaging the development of my application. It aims to draw a question (not implemented yet, I’m using a fixed value for the question id) through a query in Sqlite, and transmit to the Textviews. Here the code of the classes:
public class DBAdapter {
private SQLiteDatabase banco;
private DBHelper dbHelper;
public DBAdapter(Context context) {
dbHelper = new DBHelper(context);
}
private String[] allColumns = { DBHelper.ID, DBHelper.ALTA, DBHelper.ENUNC,
DBHelper.ALTB, DBHelper.ALTC, DBHelper.ALTD, DBHelper.ALTE, DBHelper.ALTOK};
public Cursor AcessarQuestao(int numquest, SQLiteDatabase bank){
Cursor cursorquestao;
bank = dbHelper.getWritableDatabase();
cursorquestao= bank.query(DBHelper.TABLE_NAME, allColumns, DBHelper.ID + " = " + numquest, null, null, null, null);
return cursorquestao;
}
}
public class QuestActivity extends AppCompatActivity {
Questao quest = new Questao();
private SQLiteDatabase bank;
TextView nuncp=(TextView)findViewById(R.id.nunciado);
TextView txt_altap=(TextView)findViewById(R.id.altea);
TextView txt_altbp=(TextView)findViewById(R.id.alteb);
TextView txt_altcp=(TextView)findViewById(R.id.altec);
TextView txt_altdp=(TextView)findViewById(R.id.alted);
TextView txt_altep=(TextView)findViewById(R.id.altee);
DBAdapter acesso = new DBAdapter(getBaseContext());
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.questoes);
TextView nunc=(TextView)findViewById(R.id.nunciado);
TextView txt_alta=(TextView)findViewById(R.id.altea);
TextView txt_altb=(TextView)findViewById(R.id.alteb);
TextView txt_altc=(TextView)findViewById(R.id.altec);
TextView txt_altd=(TextView)findViewById(R.id.alted);
TextView txt_alte=(TextView)findViewById(R.id.altee);
String password="txt";
Cursor obterquestao = acesso.AcessarQuestao(0, bank);
if( obterquestao != null && obterquestao.moveToFirst() ){
quest.setEnunc(obterquestao.getString(obterquestao.getColumnIndex(DBHelper.ENUNC)));
quest.setAlta(obterquestao.getString(obterquestao.getColumnIndex(DBHelper.ALTA)));
quest.setAltb(obterquestao.getString(obterquestao.getColumnIndex(DBHelper.ALTB)));
quest.setAltc(obterquestao.getString(obterquestao.getColumnIndex(DBHelper.ALTC)));
quest.setAltd(obterquestao.getString(obterquestao.getColumnIndex(DBHelper.ALTD)));
quest.setAlte(obterquestao.getString(obterquestao.getColumnIndex(DBHelper.ALTE)));
quest.setAltok(obterquestao.getString(obterquestao.getColumnIndex(DBHelper.ALTOK)));
}
nuncp.setText(quest.getEnunc());
txt_altap.setText(quest.getAlta());
txt_altbp.setText(quest.getAltb());
txt_altcp.setText(quest.getAltc());
txt_altdp.setText(quest.getAltd());
txt_altep.setText(quest.getAlte());
}/*
public void verificarResposta(View v) {
switch (v.getId()) {
case R.id.baltea:
quest.setResp(txt_altap.getText().toString());
if(quest.getResp().equals(quest.getAltok())){
Toast.makeText(getApplicationContext(), "Acertou!", Toast.LENGTH_SHORT).show();
}
break;
case R.id.balteb:
quest.setResp(txt_altbp.getText().toString());
if(quest.getResp().equals(quest.getAltok())){
Toast.makeText(getApplicationContext(), "Acertou!", Toast.LENGTH_SHORT).show();
}
break;
case R.id.baltec:
quest.setResp(txt_altcp.getText().toString());
if(quest.getResp().equals(quest.getAltok())){
Toast.makeText(getApplicationContext(), "Acertou!", Toast.LENGTH_SHORT).show();
}
break;
case R.id.balted:
quest.setResp(txt_altdp.getText().toString());
if(quest.getResp().equals(quest.getAltok())){
Toast.makeText(getApplicationContext(), "Acertou!", Toast.LENGTH_SHORT).show();
}
break;
case R.id.baltee:
quest.setResp(txt_altep.getText().toString());
if(quest.getResp().equals(quest.getAltok())){
Toast.makeText(getApplicationContext(), "Acertou!", Toast.LENGTH_SHORT).show();
}
break;
}
}*/
}
public class DBHelper extends SQLiteOpenHelper {
private static final String DATABASE_NAME = "bancoquestoes.db";
public static final String TABLE_NAME = "quests";
private static final int DATABASE_VERSION = 1;
public static final String ID = "_id";
public static final String ENUNC = "enunc";
public static final String ALTA = "alta";
public static final String ALTB = "altb";
public static final String ALTC = "altc";
public static final String ALTD = "altd";
public static final String ALTE = "alte";
public static final String ALTOK = "altok";
private String[] allColumns = { DBHelper.ID, DBHelper.ALTA, DBHelper.ENUNC,
DBHelper.ALTB, DBHelper.ALTC, DBHelper.ALTD, DBHelper.ALTE, DBHelper.ALTOK};
private static final String CRIAR_TABELA="create table " + TABLE_NAME + "(" +
ID + " integer primary key autoincrement, " +
ENUNC + " text not null, " +
ALTA + " text not null, " +
ALTB + " text not null, " +
ALTC + " text not null, " +
ALTD + " text not null, " +
ALTE + " text not null, " +
ALTOK + " text not null);";
public DBHelper(Context context){
super(context, DATABASE_NAME, null, DATABASE_VERSION);
}
@Override
public void onCreate(SQLiteDatabase db) {
db.execSQL(CRIAR_TABELA);
ContentValues values = new ContentValues();
values.put(DBHelper.ENUNC, "Qual a resposta certa?");
values.put(DBHelper.ALTA, "Alternativa 1");
values.put(DBHelper.ALTB, "Alternativa 2");
values.put(DBHelper.ALTC, "Alternativa 3(ok)");
values.put(DBHelper.ALTD, "Alternativa 4");
values.put(DBHelper.ALTE, "Alternativa 5");
values.put(DBHelper.ALTOK, "Alternativa 3(ok)");
db.insert(TABLE_NAME, null, values );
}
@Override
public void onUpgrade(SQLiteDatabase db, int i, int i1) {
db.execSQL("DROP TABLE IF EXISTS " + TABLE_NAME);
onCreate(db);
}
}
However, in doing so, the following error occurs:
10-05 14:05:27.626 15291-15291/com.teacherfox.legendary.teacherfox E/AndroidRuntime: FATAL EXCEPTION: main java.lang.RuntimeException: Unable to instantiate activity ComponentInfo{com.teacherfox.legendary.teacherfox/com.teacherfox.legendary.teacherfox.QuestActivity}: java.lang.NullPointerException at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2038) at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2139) at android.app.ActivityThread.access$700(ActivityThread.java:143) at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1241) at android.os.Handler.dispatchMessage(Handler.java:99) at android.os.Looper.loop(Looper.java:137) at android.app.ActivityThread.main(ActivityThread.java:4963) at java.lang.reflect.Method.invokeNative(Native Method) at java.lang.reflect.Method.invoke(Method.java:511) at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1038) at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:805) at dalvik.system.NativeStart.main(Native Method) Caused by: java.lang.NullPointerException at android.support.v7.app.AppCompatDelegateImplBase.(AppCompatDelegateImplBase.java:68) at android.support.v7.app.AppCompatDelegateImplV7.(AppCompatDelegateImplV7.java:146) at android.support.v7.app.AppCompatDelegateImplV11.(AppCompatDelegateImplV11.java:28) at android.support.v7.app.AppCompatDelegateImplV14.(AppCompatDelegateImplV14.java:41) at android.support.v7.app.AppCompatDelegate.create(AppCompatDelegate.java:190) at android.support.v7.app.AppCompatDelegate.create(AppCompatDelegate.java:172) at android.support.v7.app.AppCompatActivity.getDelegate(AppCompatActivity.java:512) at android.support.v7.app.AppCompatActivity.findViewById(AppCompatActivity.java:18) at com.teacherfox.legendary.teacherfox.QuestActivity.(QuestActivity.java:18) at java.lang.Class.newInstanceImpl(Native Method) at java.lang.Class.newInstance(Class.java:1319) at android.app.Instrumentation.newActivity(Instrumentation.java:1068) at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2029) at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2139) at android.app.ActivityThread.access$700(ActivityThread.java:143) at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1241) at android.os.Handler.dispatchMessage(Handler.java:99) at android.os.Looper.loop(Looper.java:137) at android.app.ActivityThread.main(ActivityThread.java:4963) at java.lang.reflect.Method.invokeNative(Native Method) at java.lang.reflect.Method.invoke(Method.java:511) at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1038 at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:805) at dalvik.system.NativeStart.main(Native Method)
I’ve tried everything, but the mistake continues. Can anyone tell me what I’m doing wrong?
Edit: The Androidmanifest
<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="com.teacherfox.legendary.teacherfox">
<application
android:allowBackup="true"
android:icon="@mipmap/ic_launcher"
android:label="@string/app_name"
android:supportsRtl="true"
android:theme="@style/AppTheme">
<activity android:name=".MainActivity">
<intent-filter>
<action android:name="android.intent.action.MAIN" />
<category android:name="android.intent.category.LAUNCHER" />
</intent-filter>
</activity>
<activity
android:name=".QuestActivity"
android:label="@string/app_name">
</activity>
</application>
</manifest>
You added the Activity
QuestActivityin hisAndroidManifest.xml? By mistake, probably this is the problem.– user28595
But it is not, when I comment the line of the method Accessquestao() the error does not happen. But I need to query the database daods.
– André Sousa
Add your
AndroidManifest.xmlediting the question, the problem originates by failing to declare Activity in this file and trying to invoke it in the application.– user28595
Added the manifest.
– André Sousa