I am making a "Note" program to practice and learn - my first "freestyle" project after reading a book on the subject. The way i figured i would do this is to store the title and content of the note in a SQLite table, and insert and remove from the table as needed.
The first activity consists of a ListView which gets all the notes(rows) from the DB. The user is supposed to press a button at the first activity, which says "New note", which then leads to another activity where you can enter the title and the content of the note, press the "Save" button, and then with an intent, return to the activity with the ListView where the newly added note plus all earlier created notes are displayed in the ListView.
My problem is that when the intent starts the activity with the ListView from the NewNote activity, the newly added note wont show in the ListView at once. If i then add a new note again, it returns to the first activity, but then the note i added first is displayed. And so it goes on. In other words the list on the first activity is always "one note behind", as it only adds the note i added the last time and not the one i recently added. Maybe its a bad explanation, but i think thats as clear as it gets. I spent alot of time today logging and trying to find the problem but i cant seem to figure this out on my own.
Here is my code.
Starting with my database class:
public class DatabaseHandler extends SQLiteOpenHelper {
private static final String DATABASE_NAME = "DB";
private static final int DATABASE_VERSION = 1;
private static final String TABLE_NOTES = "Notes";
private static final String KEY_ID = "id";
private static final String KEY_TITLE = "title";
private static final String KEY_CONTENT = "content";
public DatabaseHandler(Context context) {
super(context, DATABASE_NAME, null, DATABASE_VERSION);
}
#Override
public void onCreate(SQLiteDatabase db) {
String CREATE_PERSON_TABLE = "CREATE TABLE " + TABLE_NOTES + "(" + KEY_ID + " INTEGER PRIMARY KEY," + KEY_TITLE + " TEXT," + KEY_CONTENT + " INTEGER" + ")";
db.execSQL(CREATE_PERSON_TABLE);
}
public void dropTable() {
SQLiteDatabase db = this.getReadableDatabase();
db.execSQL("DROP TABLE IF EXISTS " + TABLE_NOTES);
}
#Override
public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
db.execSQL("DROP TABLE IF EXISTS " + TABLE_NOTES);
onCreate(db);
}
public void newNote(String title, String content) {
SQLiteDatabase db = this.getReadableDatabase();
ContentValues values = new ContentValues();
values.put(KEY_TITLE, title);
values.put(KEY_CONTENT, content);
db.insert(TABLE_NOTES, null, values);
db.close();
}
public void deleteNote(String id) {
SQLiteDatabase db = getReadableDatabase();
db.delete(TABLE_NOTES, KEY_ID + "=" + id, null);
}
public ArrayList<Note> getNotes() {
SQLiteDatabase db = this.getReadableDatabase();
ArrayList<Note> notes = new ArrayList<>();
Cursor cursor = db.query(TABLE_NOTES, new String[]{KEY_ID, KEY_TITLE, KEY_CONTENT}, null, null, null, null, KEY_ID + " DESC", null);
if (cursor != null) {
cursor.moveToFirst();
}
while(cursor.moveToNext()) {
Note note = new Note(cursor.getString(0), cursor.getString(1), cursor.getString(2));
notes.add(note);
}
db.close();
return notes;
}
public void deleteAll() {
SQLiteDatabase db = this.getReadableDatabase();
db.execSQL("delete from " + TABLE_NOTES);
db.close();
}
}
My Main activity, ListActivity:
public class ListActivity extends AppCompatActivity {
private DatabaseHandler dbh;
private ListView list;
private ArrayAdapter<Note> listAdapter;
private Button newBtn;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_list);
dbh = new DatabaseHandler(this);
Intent intent = getIntent();
String id = intent.getStringExtra("Id");
String title = intent.getStringExtra("Title");
String content = intent.getStringExtra("Content");
//If save button is pressed at NewNote
if (title != null && content != null) {
dbh.newNote(title, content);
Log.d("note", title + " added");
}
//If delete button is pressed at NewNote
if (id != null) {
dbh.deleteNote(id);
}
initWidgets();
}
public void initWidgets() {
list = findViewById(R.id.list);
newBtn = findViewById(R.id.newButton);
newBtn.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View view) {
Intent newButtonIntent = new Intent(ListActivity.this, NewNote.class);
startActivity(newButtonIntent);
}
});
list.setOnItemClickListener(new AdapterView.OnItemClickListener() {
#Override
public void onItemClick(AdapterView<?> adapterView, View view, int i, long l) {
Note note = listAdapter.getItem(i);
Intent editIntent = new Intent(ListActivity.this, EditNote.class);
editIntent.putExtra("Title", note.getTitle());
editIntent.putExtra("Content", note.getContent());
editIntent.putExtra("Id", note.getId());
startActivity(editIntent);
}
});
refreshList();
}
public void refreshList() {
listAdapter = new ArrayAdapter(this, R.layout.list_item, dbh.getNotes());
list.setAdapter(listAdapter);
Log.d("note", "View updated");
}
}
My NewNote class:
public class NewNote extends AppCompatActivity {
private EditText title;
private EditText content;
private Button btnSave;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_new_note);
initWidgets();
}
public void initWidgets() {
title = findViewById(R.id.title);
content = findViewById(R.id.content);
btnSave = findViewById(R.id.saveButton);
btnSave.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View view) {
Intent i = new Intent(NewNote.this, ListActivity.class);
i.putExtra("Title", title.getText().toString());
i.putExtra("Content", content.getText().toString());
startActivity(i);
}
});
}
}
Not really relevant as i have not implemented it fully, if you are just reading through the code you can 100% just ignore this class - my EditNote class:
public class EditNote extends AppCompatActivity {
private EditText title;
private EditText content;
private Button saveBtn;
private Button deleteBtn;
private String noteId;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_edit_note);
initWidgets();
Intent intent = getIntent();
title.setText(intent.getStringExtra("Title"));
content.setText(intent.getStringExtra("Content"));
noteId = intent.getStringExtra("Id");
}
public void initWidgets() {
title = findViewById(R.id.titleEdit);
content = findViewById(R.id.contentEdit);
deleteBtn = findViewById(R.id.deleteButton);
deleteBtn.setOnClickListener(new View.OnClickListener(){
#Override
public void onClick(View view) {
Intent i = new Intent(EditNote.this, ListActivity.class);
i.putExtra("Id", noteId);
startActivity(i);
}
});
}
}
Also there are my XML files, and a Note class which only consists of member variables and setters/getters, either of them i consider relevant. I think the problem is somewhere in the DB class, ListActivity class, or NewNote class.
Maybe this is alot to read for you and maybe its messy or im doing something wrong with the posting but i would be grateful for help on how to resolve this issue. Also if you see other things i can do better please point them out!
Thanks!
Related
I want to pass my Listview clicked item ID to other activity using intent. HoW could I do this?
You get the id and add it to the Intent as an Extra using the respective (long) putExtra, with a suitable key (first parameter).
In the other Activity you get the Intent and then get the value from the Extra using the getLongExtra using the same key (first parameter) noting that the default value should be a value (e.g. -1) that will not be an id.
Working Example
The following is a working example :-
The Database Helper DBOpenHelper.java
public class DBOpenHelper extends SQLiteOpenHelper {
public static final String DBNAME = "notes.db";
public static final int DBVERSION = 1;
public static final String TBL_NOTE = "note_table";
public static final String COL_NOTE_ID = BaseColumns._ID;
public static final String COL_NOTE_TEXT = "note_text";
private final String create_table = "CREATE TABLE IF NOT EXISTS " + TBL_NOTE + "(" +
COL_NOTE_ID + " INTEGER PRIMARY KEY, " +
COL_NOTE_TEXT + " TEXT " +
")";
private static final String drop_table = "DROP TABLE IF EXISTS " + TBL_NOTE;
public DBOpenHelper(Context context) {
super(context, DBNAME, null, DBVERSION);
}
public void onCreate(SQLiteDatabase db) {
db.execSQL(create_table);
}
public void onUpgrade(SQLiteDatabase db, int version_old, int version_new) { }
public long addNote(String note) {
SQLiteDatabase db = this.getWritableDatabase();
ContentValues cv = new ContentValues();
cv.put("NOTE_TEXT",note);
return db.insert("note_table",null,cv);
}
public Cursor getAllNotes() {
SQLiteDatabase db = this.getWritableDatabase();
return db.query(TBL_NOTE,null,null,null,null,null,null);
}
}
An instantiated instance of this is used to :
open the database (in the example it is named notes.db), it will create the database if it doesn't exist.
add data via the addNote method.
return a Cursor containing all the Notes via the getAllNotes method.
The initial activity MainActivity.java :-
public class MainActivity extends AppCompatActivity {
private ListView mListView;
private SimpleCursorAdapter MSCA;
private Cursor mCsr;
private DBOpenHelper mDBHelper;
public static final String INTENTEXTRAKEY_NOTE_ID = "iek_noteid";
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
mDBHelper = new DBOpenHelper(this);
mListView = findViewById(R.id.listView);
addSomeTestData(); //Adds a row every time the App is run (for testing)
ViewData();
}
private void ViewData(){
mCsr = mDBHelper.getAllNotes();
if (MSCA == null) {
MSCA = new SimpleCursorAdapter(
this,
android.R.layout.simple_list_item_1,
mCsr,
new String[]{DBOpenHelper.COL_NOTE_TEXT},
new int[]{android.R.id.text1},
0);
mListView.setAdapter(MSCA);
mListView.setOnItemClickListener(new AdapterView.OnItemClickListener() {
#Override
public void onItemClick(AdapterView<?> parent, View view, int position, long id) {
Intent i = new Intent(MainActivity.this,OtherActivity.class);
i.putExtra(INTENTEXTRAKEY_NOTE_ID,id);
startActivity(i);
}
});
} else {
MSCA.swapCursor(mCsr);
}
}
private void addSomeTestData() {
if(DatabaseUtils.queryNumEntries(mDBHelper.getWritableDatabase(),DBOpenHelper.TBL_NOTE) < 1) {
mDBHelper.addNote("My Note");
mDBHelper.addNote("Another Note");
mDBHelper.addNote("Yet Another Note");
mDBHelper.addNote("And so on.");
}
}
#Override
protected void onDestroy() {
super.onDestroy();
mCsr.close();
}
#Override
public void onResume()
{
super.onResume();
ViewData();
}
}
This activity :-
Adds some notes to the database (if none already exist)
Lists all of the notes in the database
sets a onItemClickListener to call the activity OtherActivity passing the id via an IntenExtra.
Notes
A CursorAdpater (SimpleCursorAdapter) in this case is ideally suited as the id is passed to the onItemClick method by the listener. NOTE this requires a column, named specifically _id (as per BaseColumns._ID) and that the column is an alias of the rowid column.
The onDestroy method has been overridden to close the Cursor when done with it (i.e. when the Activity is detsroyed). This isn't so important in the initial actiivty as it's lifetime would typically be for the entire App (closing the Cursor in hierarchically lower Activities is more important).
The ViewData method manages a single instance of the adapter (i.e. creating it only when it hasn't been instantiated) and also refreshing of the ListView. Hence why it is called in the overridden onResume method. i.e. another activity may add. delete or update the database so the ListView will updated upon return.
The activity called from the initial activity OtherActivity.java
public class OtherActivity extends AppCompatActivity {
TextView mNoteId;
Button mDone;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_other);
mNoteId = this.findViewById(R.id.noteid);
mDone = this.findViewById(R.id.done);
mDone.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
finish();
}
});
Intent i = this.getIntent();
long id = i.getLongExtra(MainActivity.INTENTEXTRAKEY_NOTE_ID,-1);
mNoteId.setText(String.valueOf(id));
}
}
This activity :-
sets the onClickListener of the button to return to the calling/invoking activity.
extracts the id from the Intent Extras passed to the activity from the calling activity and sets the noteid TextView with the extracted value (the passed id).
Result
Initially :-
Clicking Yet Another Note :-
As Yet Another Note was the third note added it's id is 3.
I am trying to create a database, but nothing happening with my code. I know this question is very basic but I am a new learner so I could not solve my problem so kindly help me.
public class DatabaseHelper extends SQLiteOpenHelper {
private static final String DATABASE_NAME="employeedb";
private static final String TABLE_NAME="EMPLOYEETABLE";
private static final int DATABASE_VERSION=1;
private static final String EID="_id";
private static final String NAME="Name";
private static final String CREATE_TABLE="CREATE TABLE "+TABLE_NAME+" ("+EID+" INTEGER PRIMARY AUTOINCREMENT, "+NAME+" VARCHAR(255))";
private static final String DROP_TABLE="DROP TABLE "+TABLE_NAME+"IF EXISTS";
private Context context;
public DatabaseHelper(Context context) {
super(context, DATABASE_NAME, null, DATABASE_VERSION);
this.context = context;
Message.message(context, "Constructor called.");
}
#Override
public void onCreate(SQLiteDatabase db) {
try {
Message.message(context, "onCreate called.");
db.execSQL(CREATE_TABLE);
}
catch (Exception e)
{
Message.message(context, ""+e);
}
}
#Override
public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
try {
Message.message(context, "onUpgrade called.");
db.execSQL(DROP_TABLE);
onCreate(db);
} catch (SQLException e) {
Message.message(context, ""+e);
}
}
}
Here is Message Class that only one method
public class Message {
public static void message(Context context, String message){
Toast.makeText(context,message,Toast.LENGTH_SHORT);
}
}
Here is MainActivity Code where i call the getWritabeDatase Method.
public class MainActivity extends Activity implements MyDialog.Communicator {
LinearLayout layout;
TextView txt;
TextView date;
DatabaseHelper dbhelper;
#Override
protected void onCreate(Bundle savedInstanceState){
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
layout = (LinearLayout) findViewById(R.id.layoutbottom);
date = (TextView) findViewById(R.id.date);
txt =(TextView) findViewById(R.id.title);
GeneralMethods generalmethods = new GeneralMethods(this,this);
dbhelper = new DatabaseHelper(this);
SQLiteDatabase sqLiteDatabase = dbhelper.getWritableDatabase();
}
public void showDialog(View v){
FragmentManager manager = getFragmentManager();
MyDialog myDialog = new MyDialog();
myDialog.show(manager,"MyDialog");
}
#Override
public void onDialogueMessage(String message) {
date.setText(message);
}
}
You onCreate will get called when you first access the database using the helper.
Any call to either
getReadableDatabase() or getWritableDatabase()
will cause the onCreate to get triggered and only then. Your onUpgrade will trigger when you change the database version of an already existing schema.
Also as per SQLite documentation, an integer primary key will automatically get incremented to the max+1 value on it's own.
Adding an Auto increment causes unnecessary explicit overhead and changes the rowid selection algorithm and they do not recommend it.
You have forgotten the show() for the toast in your Message class
Toast.makeText(context,message,Toast.LENGTH_SHORT).show();
Basically without the show(), the Toast will not get shown, it will just get created. Now since onCreate gets called only once, to check if it's working , uninstall and reinstall the app or clear it's data before testing
This question already has answers here:
What is a NullPointerException, and how do I fix it?
(12 answers)
Closed 5 years ago.
I have watched so many solution and applied all but still getting null pointer exception in my code. Here is my code kindly have a look and reply as fast as anyone can. Thanks in advance.
DBHandler.java Class code
public class DBHandler extends SQLiteOpenHelper {
//Database Version
private static final int DATABASE_VERSION=1;
// Database Name
private static final String DATABASE_NAME="Patient.db";
//Table Name
private static final String TABLE_NAME="patientDetail";
//Table Columns Names
private static final String ID="id";
private static final String NAME="name";
private static final String ADDRESS="address";
private static final String PHONE_NUMBER="phone_number";
//Constructor
public DBHandler(Context context)
{
super(context,DATABASE_NAME,null,DATABASE_VERSION);
}
//Creating Tables
#Override
public void onCreate(SQLiteDatabase db) {
String CREATE_PATIENT_DETAIL_TABLE="CREATE TABLE "+TABLE_NAME+"("
+ ID+" INTEGER PRIMARY KEY AUTOINCREMENT,"
+NAME+" TEXT,"
+ADDRESS +" TEXT,"
+PHONE_NUMBER + " TEXT )" ;
db.execSQL(CREATE_PATIENT_DETAIL_TABLE);
}
#Override
public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
//Drop older tables if exist
db.execSQL("DROP TABLE IF EXIST "+TABLE_NAME);
/// Create Table again
onCreate(db);
}
public boolean insertData(String name,String address, String ph_no)
{
SQLiteDatabase db = this.getWritableDatabase();
ContentValues values= new ContentValues();
values.put(NAME,name);
values.put(ADDRESS,address);
values.put(PHONE_NUMBER,ph_no);
long result = db.insert(TABLE_NAME,null,values);
if(result == -1)
return false;
else
return true;
}
}
//insertPatient.java Class Code
public class insertPatient extends Fragment {
DBHandler mydb=null;
EditText editname,editaddress,editph_no;
Button btn_adddata;
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
View rootView = inflater.inflate(R.layout.insert_patient, container, false);
mydb = new DBHandler(getActivity());
editname=(EditText) rootView.findViewById(R.id.insert_name);
editname=(EditText) rootView.findViewById(R.id.insert_address);
editname=(EditText) rootView.findViewById(R.id.insert_ph_no);
btn_adddata=(Button) rootView.findViewById(R.id.insert_button);
btn_adddata.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
adddata();
}
});
return rootView;
}
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
mydb = new DBHandler(getActivity());
}
public void adddata()
{
mydb = new DBHandler(getActivity());
Toast.makeText(getActivity(), "working button", Toast.LENGTH_LONG).show();
try {
boolean isinserted = mydb.insertData(editname.getText().toString(), editaddress.getText().toString(), editph_no.getText().toString());
if (isinserted) {
Toast.makeText(getActivity(), "data saved", Toast.LENGTH_LONG).show();
} else {
Toast.makeText(getActivity(), "data Not saved", Toast.LENGTH_LONG).show();
}
}
catch (Exception e) {
Toast.makeText(getActivity(), String.valueOf(e), Toast.LENGTH_LONG).show();
}
}
}
I have appllied so many solutions like either button is initialized or not, getactivity(), getcontext() and getbasecontext() for initializtion of dbhandler object, also made many changes in my db handler with different solutions but still got the same error. I did not checked my solution for activity only as i am using fragment classes so i tried it only in it.
Your problem is all your editText you are getting ids are assigned to editname instead of the ones you need, and you are using their getText method.
In your insertPatient class:
editname=(EditText) rootView.findViewById(R.id.insert_name);
editname=(EditText) rootView.findViewById(R.id.insert_address);
editname=(EditText) rootView.findViewById(R.id.insert_ph_no);
to:
editname=(EditText) rootView.findViewById(R.id.insert_name);
editaddress=(EditText) rootView.findViewById(R.id.insert_address);
editph_no=(EditText) rootView.findViewById(R.id.insert_ph_no);
you have not initialize editaddress and editph_no. you are only initializing editname for three times with diff ids.
see below line in your code
editname=(EditText) rootView.findViewById(R.id.insert_name);
editname=(EditText) rootView.findViewById(R.id.insert_address);
editname=(EditText) rootView.findViewById(R.id.insert_ph_no);
your are getting value from editaddress and editph_no and it throws exception
boolean isinserted = mydb.insertData(editname.getText().toString(), editaddress.getText().toString(), editph_no.getText().toString());
edit that lines to
editname=(EditText) rootView.findViewById(R.id.insert_name);
editaddress =(EditText) rootView.findViewById(R.id.insert_address);
editph_no =(EditText) rootView.findViewById(R.id.insert_ph_no);
I'm new to android. Here's one of my OnClickListeners. The thing is I don't know how to make it save when clicking the button. When I call createEventT(Event event), it says "non-static method cannot be referenced from a static context". Sometimes there's no error message, but the app crashes when clicking this button. Any ideas? Thanks.
OnClickListener:
OnClickListener doneT = new OnClickListener(){
#Override
public void onClick(View v) {
event.setTitle(inputToday.toString());
event.setYY(bearsCalendar.get(Calendar.YEAR));
event.setMM(bearsCalendar.get(Calendar.MONTH));
event.setDD(bearsCalendar.get(Calendar.DAY_OF_MONTH));
dateToday.setText(EventDBAdapter.createEventT(event));
}
};
And the event class:
public class Event {
int YY,MM,DD;
private String title;
public void setYY(int YY){this.YY=YY;}
public void setMM(int MM){this.MM=MM;}
public void setDD(int DD){this.DD=DD;}
public void setTitle(String title){this.title=title;};
public int getYY(){return YY;}
public int getMM(){return MM;}
public int getDD(){return DD;}
public String getTitle(){return title;}
}
public class EventDBAdapter{
private final Context mCtx;
static final String dbName="BearDatabase";
static final String eventTable="Events";
static final int dbVersion=1;
static final String colID="EventId";
static final String colTitle="Title";
static final String colDetails="Details";
static final String colYear="YY";
static final String colMonth="MM";
static final String colDay="DD";
static final String colHour="HH";
static final String colMinute="TT";
public DatabaseHelper mDbHelper;
public SQLiteDatabase mDb;
public EventDBAdapter(Context context){
mCtx=context;
}
private static class DatabaseHelper extends SQLiteOpenHelper{
DatabaseHelper(Context context){
super(context,dbName,null,dbVersion);
}
#Override
public void onCreate(SQLiteDatabase db) {
db.execSQL("CREATE TABLE "+eventTable+" ("+colID+" INTEGER PRIMARY KEY , "
+colTitle+" TEXT NOT NULL , "+colDetails+" TEXT , "
+colYear+" INTEGER , "+colMonth+" INTEGER , "+colDay+" INTEGER , "
+colHour+" INTEGER , "+colMinute+" INTEGER );");
}
#Override
public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
db.execSQL("DROP TABLE IF EXISTS " + eventTable);
onCreate(db);
}
}
public EventDBAdapter open() throws SQLException{
mDbHelper = new DatabaseHelper(mCtx);
mDb = mDbHelper.getWritableDatabase();
return this;
}
public void close() {
mDbHelper.close();
}
public void upgrade(){
mDbHelper = new DatabaseHelper(mCtx);
mDb = mDbHelper.getWritableDatabase();
mDbHelper.onUpgrade(mDb, 1, 0);
}
public long createEventT(Event event){
ContentValues values = new ContentValues();
values.put(colTitle,event.getTitle());
values.put(colYear,event.getYY());
values.put(colMonth, event.getMM());
values.put(colDay, event.getDD());
return mDb.insert(eventTable,null,values);
}
public long createEventI(Event event){
ContentValues values = new ContentValues();
values.put(colTitle,event.getTitle());
return mDb.insert(eventTable,null,values);
}
}
Update:
Any problems in the database? After I made the changes, the whole thing crush.
change below to
dateToday.setText(EventDBAdapter.createEventT(event));
with below and it will work.
dateToday.setText(String.valueOf(EventDBAdapter.createEventT(event)));
I hope you are initializing event object before using it in onClick. if not, then initialize it like event = new Event(); before
event.setTitle(inputToday.toString());
Unless EventDBAdapter in your question is an instance of the EventDBAdapter class, then you are attempting to use a non-static method (public long createEventT()) in a static way (by accessing it through the class name).
To access it, you first need to create an instance of EventDBAdapter. One way to achieve this would probably be (assuming you are calling this method from inside an Activity):
long date = new EventDBAdapter(this).createEventT(event);
dateToday.setText(String.valueOf(date));
There are more answers on this topic here.
This question already has answers here:
Unfortunately MyApp has stopped. How can I solve this?
(23 answers)
Closed 7 years ago.
I have a problem when I want to start a new activity wchich contains a reference to object extending SQLiteOpenHelper.
This is how I sart my activity:
// Listener for button
class LoginButtonListener implements View.OnClickListener {
#Override
public void onClick(View v) {
Intent intent = new Intent(v.getContext(), MasterUserActivity.class);
v.getContext().startActivity(intent);
}
}
My new activity:
// I will be implementing ListView in here
public class MasterUserActivity extends ListActivity {
private DBHandler dbHandler = new DBHandler(this);
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.master_user);
Toast toast = Toast.makeText(MasterUserActivity.this, "It works :)", Toast.LENGTH_LONG);
toast.show();
}
}
And my DBHandler class:
public class DBHandler extends SQLiteOpenHelper {
public DBHandler(Context contex) {
super(contex, "bankapplication.db", null, 1);
}
#Override
public void onCreate(SQLiteDatabase database) {
String query = "CREATE TABLE users ( login TEXT, password TEXT, name TEXT, "
+ "phone TEXT, country TEXT, balance TEXT)";
database.execSQL(query);
}
#Override
public void onUpgrade(SQLiteDatabase database, int oldVersion, int newVersion) {
String query = "DROP TABLE IF EXISTS users";
database.execSQL(query);
onCreate(database);
}
}
It works fine when I comment out private DBHandler dbHandler = new DBHandler(this);
What is wrong in here ?
This line is causing the error :
private DBHandler dbHandler = new DBHandler(this);
You can not call new while declaring variable, instead initialize inside onCreate method of your activity.