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I have this myDB object which is an object of the Databasehelper class, but when I try to invoke a method of that class it says that that object is null.
Class where this object:
public class Caldroid_fragment extends Fragment{
private DataBaseHelper myDB;
private CaldroidFragment caldroidFragment;
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
View rootView = inflater.inflate(R.layout.caldroid_calendar, container, false);
return rootView;
}
@RequiresApi(api = Build.VERSION_CODES.N)
@Override
public void onViewCreated(View view, Bundle savedInstanceState) {
myDB = new DataBaseHelper(getActivity());
ColorDrawable blue = new ColorDrawable(Color.BLUE);
caldroidFragment = new CaldroidFragment();
Bundle args = new Bundle();
args.putInt(CaldroidFragment.START_DAY_OF_WEEK, CaldroidFragment.MONDAY);
caldroidFragment.setArguments(args);
java.util.Calendar cal = Calendar.getInstance();
args.putInt(CaldroidFragment.MONTH, cal.get(Calendar.MONTH) + 1);
args.putInt(CaldroidFragment.YEAR, cal.get(Calendar.YEAR));
caldroidFragment.setArguments(args);
FragmentTransaction t = getChildFragmentManager().beginTransaction();
t.replace(R.id.caldroidCal, caldroidFragment);
t.commit();
}
public void addToCalendar(){
ColorDrawable blue = new ColorDrawable(Color.BLUE);
for(int i=0;i==myDB.getLastId();i++){
String dt = myDB.getDates(i);
java.text.SimpleDateFormat sdf = new java.text.SimpleDateFormat("dd-MM-yyyy");
Date teste = null;
try {
teste = sdf.parse(dt);
} catch (ParseException e) {
e.printStackTrace();
}
caldroidFragment.setBackgroundDrawableForDate(blue,teste);
}
}
}
Class where I am trying to import methods:
public class DataBaseHelper extends SQLiteOpenHelper {
public static final String DATABASE_NAME = "Exames.db";
public static final String TABLE_NAME = "Exames_table";
public static final String COL_1 = "ID";
public static final String COL_2 = "DISCIPLINA";
public static final String COL_3 = "SALA";
public static final String COL_4 = "DIA";
public static final String COL_5 = "HORA";
public DataBaseHelper(Context context) {
super(context, DATABASE_NAME, null, 1);
}
@Override
public void onCreate(SQLiteDatabase sqLiteDatabase) {
sqLiteDatabase.execSQL(" create table " + TABLE_NAME + " (ID INTEGER PRIMARY KEY AUTOINCREMENT , DISCIPLINA TEXT , SALA TEXT,DIA TEXT, HORA TEXT)" );
}
@Override
public void onUpgrade(SQLiteDatabase sqLiteDatabase, int i, int i1) {
sqLiteDatabase.execSQL("DROP TABLE IF EXISTS " + TABLE_NAME);
onCreate(sqLiteDatabase);
}
public boolean insertData(String disciplina,String sala,String dia,String hora){
SQLiteDatabase sqLiteDatabase = this.getWritableDatabase();
ContentValues values = new ContentValues();
values.put(COL_2,disciplina);
values.put(COL_3,sala);
values.put(COL_4,dia);
values.put(COL_5,hora);
long result = sqLiteDatabase.insert(TABLE_NAME,null,values);
if(result==-1){
return false;
}else
return true;
}
public int getLastId() {
SQLiteDatabase sqLiteDatabase = getWritableDatabase();
String query = "SELECT MAX(id) AS max_id FROM " + TABLE_NAME;
Cursor cursor = sqLiteDatabase.rawQuery(query, null);
int id = 0;
if (cursor.moveToFirst())
{
do
{
id = cursor.getInt(0);
} while(cursor.moveToNext());
}
return id;
}
public String getDates(int id){
SQLiteDatabase db = this.getWritableDatabase();
String date = "";
String last_query = "SELECT " + COL_4 + " FROM " + TABLE_NAME + " WHERE " + COL_1 + " = '" + id + "'";
Cursor c = db.rawQuery(last_query, null);
if (c != null && c.moveToFirst())
{
date = c.getString(0); // Return Value
}
db.close();
return date;
}
}
Class where the button is cleaved:
public class Tab1tests extends Fragment {
private ViewPager mViewPager;
private TimePickerDialog.OnTimeSetListener hourSetListener;
private DatePickerDialog.OnDateSetListener dateSetListener;
private Button date_button;
private Button hora_button;
private TextView date_text;
private TextView hora_text;
private EditText sala_text;
private Button add_test;
private String dt;
private DataBaseHelper myDB;
private Caldroid_fragment myCF;
public static String hora2;
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
final View rootView = inflater.inflate(R.layout.tab1tests, container, false);
add_test = (Button) rootView.findViewById(R.id.add_test);
date_button = (Button) rootView.findViewById(R.id.date_button);
hora_text = (TextView) rootView.findViewById(R.id.hora_text);
hora_button = (Button) rootView.findViewById(R.id.hora_button);
date_text = (TextView) rootView.findViewById(R.id.date_text);
sala_text = (EditText) rootView.findViewById(R.id.sala_text);
myCF = new Caldroid_fragment();
myDB = new DataBaseHelper(getContext());
date_button.setOnClickListener(
new View.OnClickListener() {
public void onClick(View v) {
Calendar cal = Calendar.getInstance();
int year = cal.get(Calendar.YEAR);
int month = cal.get(Calendar.MONTH);
int day = cal.get(Calendar.DAY_OF_MONTH);
DatePickerDialog date_dialog = new DatePickerDialog(
getActivity(),
android.R.style.Theme_Holo_Light_Dialog_MinWidth,
dateSetListener,
year, month, day);
date_dialog.getWindow().setBackgroundDrawable(new ColorDrawable(Color.TRANSPARENT));
date_dialog.show();
}
;
}
);
dateSetListener = new DatePickerDialog.OnDateSetListener() {
@Override
public void onDateSet(DatePicker datePicker, int year, int month, int day) {
month = month + 1;
date_button.setVisibility(View.GONE);
date_text = (TextView) rootView.findViewById(R.id.date_text);
date_text.setVisibility(View.VISIBLE);
dt = day + "-" + month + "-" + year;
SimpleDateFormat sdf = new SimpleDateFormat("dd-MM-yyyy");
try {
sdf.parse(dt);
date_text.setText(dt);
} catch (ParseException e) {
e.printStackTrace();
}
}
};
hora_button = (Button) rootView.findViewById(R.id.hora_button);
hora_button.setOnClickListener(
new Button.OnClickListener() {
public void onClick(View v) {
Calendar cal = Calendar.getInstance();
int hora = cal.get(Calendar.HOUR);
int minutos = cal.get(Calendar.MINUTE);
TimePickerDialog mTimePicker = new TimePickerDialog(getActivity(), TimePickerDialog.THEME_HOLO_LIGHT, hourSetListener, hora, minutos, true);
mTimePicker.getWindow().setBackgroundDrawable(new ColorDrawable(Color.TRANSPARENT));
mTimePicker.show();
}
}
);
hourSetListener = new TimePickerDialog.OnTimeSetListener() {
@Override
public void onTimeSet(TimePicker timePicker, int hora, int minutos) {
hora_button.setVisibility(View.INVISIBLE);
hora_text.setVisibility(View.VISIBLE);
hora2 = (hora + ":" + minutos);
hora_text.setText(hora2);
}
};
hora_text.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
Calendar cal = Calendar.getInstance();
int hora = cal.get(Calendar.HOUR);
int minutos = cal.get(Calendar.MINUTE);
TimePickerDialog mTimePicker = new TimePickerDialog(getActivity(),TimePickerDialog.THEME_HOLO_LIGHT,hourSetListener,hora,minutos,true);
mTimePicker.getWindow().setBackgroundDrawable(new ColorDrawable(Color.TRANSPARENT));
mTimePicker.show();
}
});
date_text.setOnClickListener(new View.OnClickListener(){
@Override
public void onClick(View v){
Calendar cal = Calendar.getInstance();
int year = cal.get(Calendar.YEAR);
int month = cal.get(Calendar.MONTH);
int day = cal.get(Calendar.DAY_OF_MONTH);
DatePickerDialog date_dialog = new DatePickerDialog(
getActivity(),
android.R.style.Theme_Holo_Light_Dialog_MinWidth,
dateSetListener,
year, month, day);
date_dialog.getWindow().setBackgroundDrawable(new ColorDrawable(Color.TRANSPARENT));
date_dialog.show();
}
});
addData();
return rootView;
}
public void addData(){
add_test.setOnClickListener(new View.OnClickListener(){
@Override
public void onClick(View v){
boolean isInserted = myDB.insertData("Portugues", sala_text.getText().toString(), dt, hora2);
if (isInserted){
Toast.makeText(getContext(),"Teste inserido ao calendario",Toast.LENGTH_LONG).show();
date_button.setVisibility(View.VISIBLE);
hora_button.setVisibility(View.VISIBLE);
date_text.setVisibility(View.INVISIBLE);
sala_text.setText("");
}
else{
Toast.makeText(getContext(),"Preencha todos os espaços",Toast.LENGTH_LONG).show();
}
myCF.addToCalendar();
}
});
}
}
Logcat error:
Process: com.pedrogouveia.averagemaker, PID: 24860
java.lang.NullPointerException: Attempt to invoke virtual method 'android.database.sqlite.SQLiteDatabase android.content.Context.openOrCreateDatabase(java.lang.String, int, android.database.sqlite.SQLiteDatabase$CursorFactory, android.database.DatabaseErrorHandler)' on a null object reference
java and android is not my area not, but at what moment exactly occurs the error ? so I saw the object is only instantiated in the event 'onviewcreated'. the event is being triggered ?
– Rovann Linhalis
Now that’s okay, thank you very much for your time.It happens when I click the button, that is when the addToCalendar method is called, I think yes this one.
– Pedro Gouveia
@Pedrogouveia You need to ensure that the event
onViewCreatedis being fired.– Jéf Bueno
Does not start automatically ?
– Pedro Gouveia
How can I guarantee it?
– Pedro Gouveia
Debugging the code, putting some message there to check...
– Jéf Bueno
Is being executed
– Pedro Gouveia
Is it possible to show the exact line error?
– Jéf Bueno
place the button click code as well as where the addToCalendar method is called
– Rovann Linhalis
Thanks for your time
– Pedro Gouveia
Put the complete error caught in the logcat. (where this red and this written "null", do not need to copy the rest).
– Guilherme Nascimento
OK I’ll post it now
– Pedro Gouveia