I want to make a to-do list app, and I wanted to delete the item in the list by tapping the checkbox.
I tried to make a "deleteTask"(as you see in the code) method in the database class. Also, you can see the "populateListView"
method, it provides data from the database into listview, I use it to refresh after each time a task got deleted from the database.
public void deleteTask(String task) {
SQLiteDatabase db = this.getWritableDatabase();
db.delete(TABLE_NAME, COL2 , new String[]{task});
}
public void populateListView() {
try {
mDataBaseHelper = new DataBaseHelper(MainActivity.this);
data = mDataBaseHelper.getData();
mArrayList = new ArrayList<>();
if (data.getCount() != 0) {
while (data.moveToNext()) {
mArrayList.add(data.getString(1));
ListAdapter listAdapter = new ArrayAdapter(MainActivity.this, R.layout.list_items, R.id.checkBox, mArrayList);
list = (ListView) findViewById(R.id.myListId);
list.setAdapter(listAdapter);
}
mDataBaseHelper.close();
} else {
toastMessage("the Database is empty");
}
}catch(Exception e){
Log.e(TAG, "populateListView: error"+e.getStackTrace() );
}
}
when the application gets started, I tapped the item that I want to delete, but I see that the items start to be deleted by order from above!
one by one each time I tapped any checkbox.
You want :-
public void deleteTask(String task) {
SQLiteDatabase db = this.getWritableDatabase();
db.delete(TABLE_NAME, COL2 + "=?" , new String[]{task});
}
If you weren't trapping the error by using the try/catch using db.delete(TABLE_NAME, COL2 , new String[]{task}); you would get an exception along the lines of :-
java.lang.IllegalArgumentException: Too many bind arguments. 1 arguments were provided but the statement needs 0 arguments.
However
Assuming that the issue with deleting rows sequentially rather than according to the checked item(s), is likely due to the handling of the checked items. However, as the code for this is not provided it would only be guess work to know where in the code you are going wrong.
One thing is that you do not want to be creating a new listadapter instance every time you populate the ListView.
As a hint to handling a ListView, but deleting an item when it is long-clicked based upon the COL2 value, perhaps consider the following which has been based upon your code (but deletes according to long clicking an item) :-
public void populateLisView() {
mDataBaseHelper = new DataBaseHelper(this); //<<<<<<<<<< NOTE 1
list = (ListView) this.findViewById(R.id.myListId); //<<<<<<<<<< NOTE 1
data = mDataBaseHelper.getData(); //<<<<<<<<<< get the data to be listed
if (listadapter == null) { //<<<<<<<<<< Only need to instantiate one adapter when it has not bee instantiated
listadapter = new ArrayAdapter<>(this,android.R.layout.simple_list_item_1,android.R.id.text1,data); // for convenience using a stock layout
list.setAdapter(listadapter);
//<<<<<<<<<<< add the onItemLongClick listener
list.setOnItemLongClickListener(new AdapterView.OnItemLongClickListener() {
#Override
public boolean onItemLongClick(AdapterView<?> parent, View view, int position, long id) {
mDataBaseHelper.deleteTaskByCol2(data.get(position)); //<<<<<<<<<< gets the value of the item according to it's position in the list
populateLisView(); //<<<<<<<<<< as the item has been deleted then refresh the Listview
return true; // flag the event as having been handled.
}
});
//<<<<<<<<<<< If the Adapter has been instantiated then refresh the ListView's data
} else {
listadapter.clear(); // Clear the data from the adapter
listadapter.addAll(data); // add the new changed data to the adapter
listadapter.notifyDataSetChanged(); // tell the adapter that the data has changed
}
}
NOTE 1
you would typically instantiate these variables once.
Check the comments
You may wish to edit your question to include how you are handling the check events.
The Full Working Example
DatabaseHelper.java
Note this may differ from yours a little
public class DataBaseHelper extends SQLiteOpenHelper {
public static final String DBNAME = "mydb";
public static final int DBVERSION = 1;
public static final String TABLE_NAME = "mytable";
public static final String COL1 = "col1";
public static final String COL2 = "col2";
SQLiteDatabase db;
private static final String CRT_MYTABLE_SQL = "CREATE TABLE IF NOT EXISTS " + TABLE_NAME +
"(" +
COL1 + " TEXT, " +
COL2 + " TEXT" +
")";
public DataBaseHelper(Context context) {
super(context, DBNAME, null, DBVERSION);
db = this.getWritableDatabase();
}
#Override
public void onCreate(SQLiteDatabase db) {
db.execSQL(CRT_MYTABLE_SQL);
}
#Override
public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
}
public long addMytableRow(String col1, String col2) {
ContentValues cv = new ContentValues();
cv.put(COL1,col1);
cv.put(COL2,col2);
return db.insert(TABLE_NAME,null,cv);
}
public ArrayList<String> getData() {
ArrayList<String> rv = new ArrayList<>();
Cursor csr = db.query(TABLE_NAME,null,null,null,null,null,null);
while (csr.moveToNext()) {
rv.add(csr.getString(csr.getColumnIndex(COL2)));
}
csr.close();
return rv;
}
public void deleteTaskByCol2(String task) {
db.delete(TABLE_NAME,COL2 + "=?",new String[]{task});
}
}
MainActivity.java
i.e. an example activity that is based upon your code, but according to the above :-
public class MainActivity extends AppCompatActivity {
DataBaseHelper mDataBaseHelper;
ArrayList<String> data;
ListView list;
ArrayAdapter<String> listadapter;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
addSomeTestData();
populateLisView();
}
private void example001() {
}
public void populateLisView() {
mDataBaseHelper = new DataBaseHelper(this);
list = (ListView) this.findViewById(R.id.myListId);
data = mDataBaseHelper.getData();
if (listadapter == null) {
listadapter = new ArrayAdapter<>(this,android.R.layout.simple_list_item_1,android.R.id.text1,data);
list.setAdapter(listadapter);
list.setOnItemLongClickListener(new AdapterView.OnItemLongClickListener() {
#Override
public boolean onItemLongClick(AdapterView<?> parent, View view, int position, long id) {
//mDataBaseHelper.deleteTaskWrong(data.get(position)); // ooops
mDataBaseHelper.deleteTaskByCol2(data.get(position));
populateLisView();
return true;
}
});
} else {
listadapter.clear();
listadapter.addAll(data);
listadapter.notifyDataSetChanged();
}
}
private void addSomeTestData() {
if (mDataBaseHelper == null) {
mDataBaseHelper = new DataBaseHelper(this);
}
if (DatabaseUtils.queryNumEntries(mDataBaseHelper.getWritableDatabase(),DataBaseHelper.TABLE_NAME) > 0) return;
mDataBaseHelper.addMytableRow("Test1","Test1");
mDataBaseHelper.addMytableRow("Test2","Test2");
mDataBaseHelper.addMytableRow("Test3","Test3");
mDataBaseHelper.addMytableRow("Test4","Test4");
}
}
Note AddSomeTestData adds some data for testing/demonstration.
Result
When first run :-
After LongClicking Test 2
i.e. the long clicked item has been removed (from the list and the database) and the list refreshed.
Try to replace
db.delete(TABLE_NAME, COL2 , new String[]{task});
By
db.delete(TABLE_NAME, COL2 + " = ?" , new String[]{task});
Related
I am setting a new activity named Dispatch Report, which has two Spinners: CustomerSpinner and LotSpinner.
LotSpinner shows all Lots in Dispatch Table instead of showing only those Lots which are related to the Customer selected in the first Spinner.
I have fetched CustomerSpinner Value from Dispatch Table. In LotSpinner also fetched Lot numbers from Dispatch Table, but not Filtered according to customer selection.
DispatchReportActivity.Java
// Fetching customer from dispatch table
private void loadCustomerNameDispatch() {
DatabaseHelper db = new DatabaseHelper( getApplicationContext() );
List<String> lables1 = db.getFirmNAmeMoveStock();
ArrayAdapter<String> dataAdapter = new ArrayAdapter<String>(this,
android.R.layout.simple_spinner_item, lables1);
dataAdapter .setDropDownViewResource(android.R.layout.simple_spinner_dropdown_item);
// attaching data adapter to spinner
spinCustomer.setAdapter(dataAdapter);
spinCustomer.setOnItemSelectedListener(this);
}
// Fetching lot from dispatch table
private void loadLotbyCustomerDispatch() {
// database handler
DatabaseHelper db = new DatabaseHelper(getApplicationContext());
// Spinner Drop down elements
List<String> lables = db.getLotbyCustomer();
// Creating adapter for spinner
ArrayAdapter<String> dataAdapter = new ArrayAdapter<String>(this,
android.R.layout.simple_spinner_item, lables);
// Drop down layout style - list view with radio button
dataAdapter
.setDropDownViewResource(android.R.layout.simple_spinner_dropdown_item);
// attaching data adapter to spinner
spinLotbyCustomer.setAdapter(dataAdapter);
}
DATABASEHELPER.Java
//Get firm name in Dispatch Stock Report screen
public List < String > getFirmNAmeMoveStock() {
List < String > labels = new ArrayList < String > ();
// Select all query
String selectQuery = "SELECT * FROM " + Table_Inventory;
SQLiteDatabase db = this.getReadableDatabase();
Cursor cursor = db.rawQuery(selectQuery, null);
// Looping through all rows and adding to list
if (cursor.moveToFirst()) {
do {
labels.add(cursor.getString(3));
Set < String > set = new HashSet < >(labels);
labels.clear();
labels.addAll(set);
} while ( cursor . moveToNext ());
}
// Closing connection
cursor.close();
db.close();
// Returning lables
return labels;
}
// Method to get Lot No. in Dispatch Stock Report Activity
public List < String > getLotbyCustomer() {
List < String > labels1 = new ArrayList < String > ();
// Select all query
String selectQuery = "SELECT * FROM " + Table_StockDispatch;
SQLiteDatabase db = this.getReadableDatabase();
Cursor cursor = db.rawQuery(selectQuery, null);
// looping through all rows and adding to list
if (cursor.moveToFirst()) {
do {
labels1.add(cursor.getString(4));
Set < String > set = new HashSet < >(labels1);
labels1.clear();
labels1.addAll(set);
} while ( cursor . moveToNext ());
}
// Closing connection
cursor.close();
db.close();
// Returning lables
return labels1;
}
There will be multiple customers, and each customer could have multiple Lots, so I want the second spinner to show only those Lots which are relevant to the customer selected in the first Spinner.
I'd suggest utilising Cursor's and Cursor adapters which can make matter simpler as :-
there is no need for intermediate arrays (one of your issues is that String arrays do not provide sufficient information)
CursorAdapters are designed to handle id (albiet a requirement that these exists in the Cursor with the column name _id (see the use of BaseColumns._ID below)).
The following is a basic example of related spinners based loosely upon your requirements.
First the DatbaseHelper DatabaseHelper.java
Two tables are defined/created Customers and Lots, methods to add data for each exist as do methods to extract a list from each of the tables. The lots extracted are based upon the customer to which they reference/belong to/associate with.
public class DatabaseHelper extends SQLiteOpenHelper {
public static final String DBNAME = "mydb";
public static final int DBVERSION = 1;
public static final String TBL_CUSTOMER = "customer";
public static final String TBL_LOT = "lot";
public static final String COL_CUSTOMER_ID = BaseColumns._ID; //<<<<<<<<<< column name is _id (needed for Cursor Adapter)
public static final String COL_CUSTOMER_NAME = "customer_name";
public static final String COL_LOT_ID = BaseColumns._ID; //<<<<<<<<<< column name is _id (needed for Cursor Adapter)
public static final String COL_LOT_NAME = "lot_name";
public static final String COL_LOT_CUSTOMERREFERENCE = "customer_refererence";
SQLiteDatabase mDB;
public DatabaseHelper(Context context) {
super(context, DBNAME, null, DBVERSION);
mDB = this.getWritableDatabase(); //<<<<<<<<<< get the database connection (force create when constructing helper instance)
}
#Override
public void onCreate(SQLiteDatabase db) {
String crt_customer_table_sql = "CREATE TABLE IF NOT EXISTS " + TBL_CUSTOMER + "(" +
COL_CUSTOMER_ID + " INTEGER PRIMARY KEY, " +
COL_CUSTOMER_NAME + " TEXT UNIQUE " +
")";
String crt_lot_table_sql = "CREATE TABLE IF NOT EXISTS " + TBL_LOT + "(" +
COL_LOT_ID + " INTEGER PRIMARY KEY, " +
COL_LOT_NAME + " TEXT, " +
COL_LOT_CUSTOMERREFERENCE + " INTEGER " +
/*?????????? OPTIONAL IF FOREIGN KEYS ARE TURNED ON
"REFERENCES " + TBL_CUSTOMER + "(" +
COL_CUSTOMER_ID +
")" +
*/
")";
db.execSQL(crt_customer_table_sql);
db.execSQL(crt_lot_table_sql);
}
#Override
public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
}
public long addCustomer(String name) {
ContentValues cv = new ContentValues();
cv.put(COL_CUSTOMER_NAME,name);
return mDB.insert(TBL_CUSTOMER,null,cv);
}
public long addLot(String name, long customer_reference) {
ContentValues cv = new ContentValues();
cv.put(COL_LOT_NAME,name);
cv.put(COL_LOT_CUSTOMERREFERENCE,customer_reference);
return mDB.insert(TBL_LOT,name,cv);
}
public Cursor getCustomers() {
return mDB.query(TBL_CUSTOMER,null,null,null,null,null,COL_CUSTOMER_NAME);
}
public Cursor getLotsPerCustomer(long customer_id) {
String whereclause = COL_LOT_CUSTOMERREFERENCE + "=?";
String[] whereargs = new String[]{String.valueOf(customer_id)};
return mDB.query(TBL_LOT,null,whereclause,whereargs,null,null,COL_LOT_NAME);
}
}
Note the above is pretty straight-forward. However, it would obviously need to be adapted to suit you App.
The second code is the activity that utilises the above and incorporates the 2 linked/related spinners where the selectable Lots are as per those lots associated with the currently selected customer.
The layout used for the activity is very basic, it just has two spinners. The spiners use the stock Simple_List_Item_2 layout (2 has been used to allow the all important ID's to be viewed (typically the user would not be shown the ID's)).
In short whenever a selection is made in the Customer spinner the Lot spinner is managed (setup or refreshed) based upon the customer id which is used to select the related/reference lots.
public class MainActivity extends AppCompatActivity {
Context mContext;
DatabaseHelper mDBHlpr;
SimpleCursorAdapter mCustomerSCA, mLotSCA;
Spinner mCustomerList, mLotList;
Cursor mCustomers, mLots;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
mContext = this;
mDBHlpr = new DatabaseHelper(this);
mCustomerList = this.findViewById(R.id.customer_list);
mLotList = this.findViewById(R.id.lot_list);
addTestingDataIfNoData(); //Go and add some testing data if there is none
manageCustomerSpinner();
}
private void manageCustomerSpinner() {
mCustomers = mDBHlpr.getCustomers();
if (mCustomerSCA == null) {
mCustomerSCA = new SimpleCursorAdapter(
this,
android.R.layout.simple_list_item_2,
mCustomers,
new String[]{
DatabaseHelper.COL_CUSTOMER_NAME,
DatabaseHelper.COL_CUSTOMER_ID
},
new int[]{
android.R.id.text1,
android.R.id.text2
},
0
);
mCustomerList.setAdapter(mCustomerSCA);
mCustomerList.setOnItemSelectedListener(new AdapterView.OnItemSelectedListener() {
#Override
public void onItemSelected(AdapterView<?> parent, View view, int position, long id) {
manageLotSpinner(id); //<<<<<<<<<< WHENEVER CUSTOMER IS SELECTED THE LOT SPINNER IS MANAGED >>>>>>>>>>
}
#Override
public void onNothingSelected(AdapterView<?> parent) {
}
});
} else {
mCustomerSCA.swapCursor(mCustomers);
}
}
private void manageLotSpinner(long id) {
mLots = mDBHlpr.getLotsPerCustomer(id);
if (mLotSCA == null) {
mLotSCA = new SimpleCursorAdapter(
this,
android.R.layout.simple_list_item_2,
mLots,
new String[]{
DatabaseHelper.COL_LOT_NAME,
DatabaseHelper.COL_LOT_ID
},
new int[]{
android.R.id.text1,
android.R.id.text2
},
0
);
mLotList.setAdapter(mLotSCA);
} else {
mLotSCA.swapCursor(mLots);
}
}
private void addTestingDataIfNoData() {
if (DatabaseUtils.queryNumEntries(mDBHlpr.getWritableDatabase(),DatabaseHelper.TBL_CUSTOMER) < 1) {
mDBHlpr.addCustomer("Fred");
mDBHlpr.addCustomer("Mary");
mDBHlpr.addCustomer("Sue");
mDBHlpr.addCustomer("Alan");
mDBHlpr.addLot("Lot001",2); // Lot for mary
mDBHlpr.addLot("Lot002",1); // Lot for fred
mDBHlpr.addLot("Lot003",4); // Lot for ala
mDBHlpr.addLot("Lot004",3); // Lot for sue
mDBHlpr.addLot("Lot005",3); // Lot for sue
mDBHlpr.addLot("Lot006",3); // Lot for use
mDBHlpr.addLot("Lot007",2); // Lot for mary
mDBHlpr.addLot("Lot008",2); // Lot for mary
mDBHlpr.addLot("Lot009",2); // Lot for mary
mDBHlpr.addLot("Lot0010",2); // Lot for mary
mDBHlpr.addLot("Lot0020",1); // Lot for Fred
mDBHlpr.addLot("Lot00130",4); // Lot for Alan
mDBHlpr.addLot("Lot00130",3); // Lot for Sue
}
}
}
Result Example
Initial
Alan is initial selection due to sort order
After Selecting Mary
Note Lot names, as used, are not really suited to sorting
I just implemented an SQLite database for a simple to do app for persistence. However, the problem is that when I restart the app, I do not have my data that is stored in an SQLite database. The following is my SQLite helper class:
public class DatabaseHelper extends SQLiteOpenHelper {
public static final String DATABASE_NAME = "todo.db";
public static final String TABLE_NAME = "student";
public static final String ID = "id";
public static final String TO_DO = "todo";
public DatabaseHelper(Context context) {
super(context, DATABASE_NAME, null, 1);
}
#Override
public void onCreate(SQLiteDatabase sqLiteDatabase) {
String CREATE_TO_DO_TABLE = "CREATE TABLE "
+ TABLE_NAME
+ "("
+ ID
+ " INTEGER PRIMARY KEY AUTOINCREMENT, "
+ TO_DO
+ " TEXT"
+ ")";
sqLiteDatabase.execSQL(CREATE_TO_DO_TABLE);
}
#Override
public void onUpgrade(SQLiteDatabase sqLiteDatabase, int oldVersion, int newVersion) {
sqLiteDatabase.execSQL("DROP TABLE IF EXISTS " + TABLE_NAME);
onCreate(sqLiteDatabase);
}
public boolean insertData(String todo){
SQLiteDatabase sqLiteDatabase = this.getWritableDatabase();
ContentValues contentValues = new ContentValues();
contentValues.put(TO_DO, todo);
sqLiteDatabase.insert(TABLE_NAME, null, contentValues);
return true;
}
}
And in my MainActivity.java, I'm adding my List items into the database as well as the ListView.
public class MainActivity extends AppCompatActivity {
DatabaseHelper databaseHelper;
private final int REQUEST_CODE = 10;
ArrayList <String> toDoItems = new ArrayList<>();
ArrayAdapter<String> adapter;
ListView listItems;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
listItems = (ListView) findViewById(R.id.listViewItems);
adapter = new ArrayAdapter<>(this, android.R.layout.simple_list_item_1, toDoItems);
listItems.setAdapter(adapter);
databaseHelper = new DatabaseHelper(this);
...
}
public void addItem(View v){
EditText newItem = (EditText) findViewById(R.id.itemInputEditText);
String item = newItem.getText().toString();
databaseHelper.insertData(item);
adapter.add(item);
newItem.setText("");
}
}
I believe I need to do something in the onCreate method but my addItem(View v) method is called through the button onClick.
as #cristian_franco said, the toDoItems is empty yet. What you need to do is to create another method in DatabaseHelper class like this.
public ArrayList<String> showStudents(){
ArrayList<String> list = new ArrayList<String>();
SQLiteDatabase db = this.getReadableDatabase();
String query = "SELECT * FROM " + TABLE_NAME;
Cursor cursor = db.rawQuery(query, null);
if (cursor.moveToFirst()) {
do {
list.add(cursor.getString(0)+" "+cursor.getString(1));
} while (cursor.moveToNext());
}
cursor.close();
db.close();
return list;
}
and then assign toDoItems like this
databaseHelper = new DatabaseHelper(this);
toDoItems=databaseHelper.showStudents();
Let me know if there is any mistake in my code.
implment this function for get the values,
public void getDatos(){
SQLiteDatabase database = databaseHelper.getWritableDatabase();
Cursor cursor = database.rawQuery("select * from student",null);
if (cursor.moveToFirst()) {
while (!cursor.isAfterLast()) {
String name = cursor.getString(cursor.getColumnIndex("todo"));
Toast.makeText(getApplicationContext(), name, Toast.LENGTH_LONG).show();
cursor.moveToNext();
}
}
}
yout funciion for save is correct only you need get the information
I am facing a problem with Android app.So. I have 3 activities that are opening one after another with OnItemClickListener. From first to second activity I have no trouble since I just have to load ArrayList in listview in the second activity.The third activity is opening when I click an item from the listview in second activity and in a third activity I want to open data from my database for the clicked item.
Here is some code:
1.The second activity:
DatabaseHelper myDB;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.viewlistcontents_layout);
ListView listView = (ListView) findViewById(R.id.listView);
myDB = new DatabaseHelper(this);
ArrayList<String> theList = new ArrayList<>();
Cursor data = myDB.getListContents();
if(data.getCount() == 0){
Toast.makeText(this, "There are no contents in this list!",Toast.LENGTH_LONG).show();
}else{
while(data.moveToNext()){
theList.add(data.getString(1));
ListAdapter listAdapter = new ArrayAdapter<>(this,android.R.layout.simple_list_item_1,theList);
listView.setAdapter(listAdapter);
}
}
listView.setOnItemClickListener(new AdapterView.OnItemClickListener() {
#Override
public void onItemClick(AdapterView<?> parent, View view, int position, long id) {
Intent intent = new Intent(ViewListContents.this, ElevatorInfo.class);
startActivity(intent);
}
});
}
2.Third activity where I want to get the opened item id from a database and load the third column from the database but have no idea how to do it and that is my actual question.Also, im doing the same thing as in second activity just to try to load the info from the third column in a listview but its also not working.
DatabaseHelper myDB;
#Override
ListView listView = (ListView) findViewById(R.id.listView);
myDB = new DatabaseHelper(this);
ArrayList<String> theList = new ArrayList<>();
Cursor data = myDB.getListContents();
if (data.getCount() == 0) {
Toast.makeText(this, "There are no contents in this list!", Toast.LENGTH_LONG).show();
} else {
while (data.moveToNext()) {
theList.add(data.getString(2));
ListAdapter listAdapter = new ArrayAdapter<>(this, android.R.layout.simple_list_item_1, theList);
listView.setAdapter(listAdapter);
}
}
}
public void AddData(String newEntry) {
boolean insertData = myDB.addData2(newEntry);
if(insertData == true){
Toast.makeText(this, "Data Successfully Inserted!", Toast.LENGTH_LONG).show();
}else{
Toast.makeText(this, "Something went wrong :(.", Toast.LENGTH_LONG).show();
}
}
}
3.My DatabaseHelper class.
#Override
public void onCreate(SQLiteDatabase db) {
String createTable = "CREATE TABLE " + MyDatabase.ElevatorEntry.TABLE_NAME + " ( " + MyDatabase.ElevatorEntry.COL1 + "INTEGER PRIMARY KEY AUTOINCREMENT, " +
MyDatabase.ElevatorEntry.COL2 + "TEXT" + MyDatabase.ElevatorEntry.DATE + " TEXT " + " )";
db.execSQL(createTable);
}
#Override
public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
db.execSQL("DROP IF TABLE EXISTS " + MyDatabase.ElevatorEntry.TABLE_NAME);
onCreate(db);
}
public boolean addData(String item1) {
SQLiteDatabase db = this.getWritableDatabase();
ContentValues contentValues = new ContentValues();
contentValues.put(MyDatabase.ElevatorEntry.COL2, item1);
long result = db.insert(MyDatabase.ElevatorEntry.TABLE_NAME, null, contentValues);
if (result == -1) {
return false;
} else {
return true;
}
}
public boolean addData2(String item2) {
SQLiteDatabase db = this.getWritableDatabase();
ContentValues contentValues = new ContentValues();
contentValues.put(MyDatabase.ElevatorEntry.DATE, item2);
public Cursor getListContents(){
SQLiteDatabase db = this.getWritableDatabase();
Cursor data = db.rawQuery("SELECT * FROM " + MyDatabase.ElevatorEntry.TABLE_NAME, null );
return data;
}
}
you have wrote a lot of code in the question, stay focused on what you want to ask about
side note: why this
ListAdapter listAdapter = new ArrayAdapter<>(this,android.R.layout.simple_list_item_1,theList);
listView.setAdapter(listAdapter);
is in the while loop? this should be called once, when the loop ends and all the items have been added to the list theList
while(data.moveToNext()){
theList.add(data.getString(1));
}//while loop
ListAdapter listAdapter = new ArrayAdapter<>(this,android.R.layout.simple_list_item_1,theList);
listView.setAdapter(listAdapter);
Now, for your question, at onItemClick() use position to get the item from theList then do whatever you want with it:
#Override
public void onItemClick(AdapterView<?> parent, View view, int position, long id) {
String selected = theList.get(position);
Intent intent = new Intent(ViewListContents.this, ElevatorInfo.class);
intent.putExtra("SELECTED_ITEM",selected);
startActivity(intent);
}
now you can add selected as an extra in the intent and start the next activity.
EDIT:
For how to read the value from the 2nd activity. check this answer
you need to use getIntent().getStringExtra("SELECTED_ITEM");.
I am making an app that stores a name and a mark in a database and it displays this in a listview. How can I delete an item of the listview and also of the database with a long press of the item in the listview??
Here is the code of the database helper:
public class PersonDatabaseHelper {
private static final String TAG = PersonDatabaseHelper.class.getSimpleName();
// database configuration
// if you want the onUpgrade to run then change the database_version
private static final int DATABASE_VERSION = 1;
private static final String DATABASE_NAME = "mydatabase.db";
public static String query;
// table configuration
private static final String TABLE_NAME = "person_table"; // Table name
private static final String PERSON_TABLE_COLUMN_ID = "_id"; // a column named "_id" is required for cursor
private static final String PERSON_TABLE_COLUMN_NAME = "person_name";
private static final String PERSON_TABLE_COLUMN_PIN = "person_pin";
private DatabaseOpenHelper openHelper;
private SQLiteDatabase database;
// this is a wrapper class. that means, from outside world, anyone will communicate with PersonDatabaseHelper,
// but under the hood actually DatabaseOpenHelper class will perform database CRUD operations
public PersonDatabaseHelper(Context aContext) {
openHelper = new DatabaseOpenHelper(aContext);
database = openHelper.getWritableDatabase();
}
public void insertData (String aPersonName, String aPersonPin) {
// we are using ContentValues to avoid sql format errors
ContentValues contentValues = new ContentValues();
contentValues.put(PERSON_TABLE_COLUMN_NAME, aPersonName);
contentValues.put(PERSON_TABLE_COLUMN_PIN, aPersonPin);
database.insert(TABLE_NAME, null, contentValues);
}
public Cursor getAllData () {
String buildSQL = "SELECT * FROM " + TABLE_NAME;
Log.d(TAG, "getAllData SQL: " + buildSQL);
return database.rawQuery(buildSQL, null);
}
// this DatabaseOpenHelper class will actually be used to perform database related operation
private class DatabaseOpenHelper extends SQLiteOpenHelper {
public DatabaseOpenHelper(Context aContext) {
super(aContext, DATABASE_NAME, null, DATABASE_VERSION);
}
#Override
public void onCreate(SQLiteDatabase sqLiteDatabase) {
// Create your tables here
String buildSQL = "CREATE TABLE " + TABLE_NAME + "( " + PERSON_TABLE_COLUMN_ID + " INTEGER PRIMARY KEY, " +
PERSON_TABLE_COLUMN_NAME + " TEXT, " + PERSON_TABLE_COLUMN_PIN + " TEXT )";
Log.d(TAG, "onCreate SQL: " + buildSQL);
sqLiteDatabase.execSQL(buildSQL);
}
#Override
public void onUpgrade(SQLiteDatabase sqLiteDatabase, int oldVersion, int newVersion) {
// Database schema upgrade code goes here
String buildSQL = "DROP TABLE IF EXISTS " + TABLE_NAME;
Log.d(TAG, "onUpgrade SQL: " + buildSQL);
sqLiteDatabase.execSQL(buildSQL); // drop previous table
onCreate(sqLiteDatabase); // create the table from the beginning
}
}
public void average() {
String query = "SELECT AVG("+PERSON_TABLE_COLUMN_PIN +") FROM "+TABLE_NAME;
database.rawQuery(query, null);
}
}
Well, since you have a unique ID associated with each entry in your database, you could delete based on that, like so:
public void deleteItem(int itemId){
this.getWritableDatabase().delete(TABLE_NAME, PERSON_TABLE_COLUMN_ID + "=" + itemId, null);
}
Then, when an item in your ListView is long-pressed, you could call that method to remove it from your database, and then call remove(Object) on your Adapter (or remove(int) on the List your Adapter uses), followed by notifyDataSetChanged() to ensure it updates the display correctly.
Edit: To answer your question about how to apply a long click listener to an item in your ListView, it depends on how you've implemented the Adapter. If it's's a custom adapter, you can simply set an onLongClickListener() to your root View (e.g. convertView). If you're not using that, you can try attaching an AdapterView.OnItemLongClickListener like this to your ListView:
listView.setOnItemLongClickListener(new AdapterView.OnItemLongClickListener() {
#Override
public boolean onItemLongClick(AdapterView<?> adapterView, View view, int position, long arg3) {
// get the data from your list at position, i.e. data.get(position)
// then pass that object / id to your database helper, e.g.
Person p = data.get(position);
personDatabaseHelper.deleteItem(p.getId());
data.remove(position); // or adapter.remove(p), depends on your implementation
adapter.notifyDataSetChanged(); // remove the object from your Adapter and notify it of the change
return true;
}
});
Edit 2: Using a custom Adapter
In your getView() method, add the following before returning convertView:
public View getView(final int position, View convertView, ViewGroup parent){
// your other stuff here
convertView.setOnLongClickListener(new View.OnLongClickListener() {
#Override
public boolean onLongClick(View v) {
Person p = getItem(position);
personDatabaseHelper.deleteItem(p.getId());
remove(p);
notifyDataSetChanged();
return true;
}
});
return convertView;
}
I have DB table with 10,000 rows which I want to display in the listview. I want to display first 20 and when the user scrolls down to the last item the next 20 should be loaded (and so on.). it really takes a lot of time to load all the datas in the listview so thats why i want it to load 20 datas first..
inside onCreate() Method the code is:
dbHelper = new WordDbAdapter(this);
dbHelper.open();
//Generate ListView from SQLite Database
displayListView();
then on the displayListView() method the code is like this:
#SuppressWarnings("deprecation")
private void displayListView() {
final Cursor cursor = dbHelper.fetchAllWords();
// The desired columns to be bound
String[] columns = new String[] {
WordDbAdapter.KEY_WORD,
WordDbAdapter.KEY_ROWID,
};
// the XML defined views which the data will be bound to
int[] to = new int[] {
R.id.Word,
R.id.imgStar,
};
// create the adapter using the cursor pointing to the desired data
//as well as the layout information
dataAdapter = new SimpleCursorAdapter(
this, R.layout.word_info,
cursor,
columns,
to
);
ListView listView = (ListView) findViewById(R.id.Diclist);
// Assign adapter to ListView
listView.setAdapter(dataAdapter);
listView.setOnScrollListener(new OnScrollListener(){
public void onScroll(AbsListView view, int firstVisibleItem, int visibleItemCount, int totalItemCount) {
int lastInScreen = firstVisibleItem + visibleItemCount;
if(cursor != null){
if(lastInScreen == totalItemCount && isLoadingMore == false){
isLoadingMore = true;
loadedPage ++;
new LoadWords().execute();
}
}
}
public void onScrollStateChanged(AbsListView view, int scrollState) {}
});
listView.setOnItemClickListener(new OnItemClickListener() {
#Override
public void onItemClick(AdapterView<?> listView, View view,
int position, long id) {
// Get the cursor, positioned to the corresponding row in the result set
Cursor cursor = (Cursor) listView.getItemAtPosition(position);
// Get the word name from this row in the database.
String wordSelected =
cursor.getString(cursor.getColumnIndexOrThrow("word"));
String wordSyllabication =
cursor.getString(cursor.getColumnIndexOrThrow("syllabication"));
String wordPartofSpeech =
cursor.getString(cursor.getColumnIndexOrThrow("partofspeech"));
String wordMeaning =
cursor.getString(cursor.getColumnIndexOrThrow("meaning"));
String wordSpeak =
cursor.getString(cursor.getColumnIndexOrThrow("speakword"));
EditText TextDic = (EditText) findViewById(R.id.TextDic);
TextDic.setText(wordSelected);
speakMeaning = wordMeaning;
speakSyllabication = wordSyllabication;
speakPartOfSpeech = wordPartofSpeech;
speakWord = wordSpeak;
speakGetWord = wordSelected;
//Toast.makeText(getApplicationContext(),
// wordSyllabication + "\n" + wordPartofSpeech + "\n" + wordMeaning , Toast.LENGTH_SHORT).show();
}
});
EditText TextDic = (EditText) findViewById(R.id.TextDic);
TextDic.addTextChangedListener(new TextWatcher() {
public void afterTextChanged(Editable s) {
speakWord = "";
speakMeaning = "";
}
public void beforeTextChanged(CharSequence s, int start,
int count, int after) {
}
public void onTextChanged(CharSequence s, int start,
int before, int count) {
dataAdapter.getFilter().filter(s.toString());
}
});
dataAdapter.setFilterQueryProvider(new FilterQueryProvider() {
public Cursor runQuery(CharSequence constraint) {
return dbHelper.fetchWordsByWord(constraint.toString());
}
});
}
then my AsyncTask is like this:
private class LoadWords extends AsyncTask<String, Void, Void> {
private final ProgressDialog dialog = new ProgressDialog(DictionaryActivity.this);
Cursor cursor = dbHelper.fetchAllWords();
#Override
protected void onPreExecute() {
this.dialog.setMessage("Loading books...");
this.dialog.show();
}
public void execute() {
// TODO Auto-generated method stub
}
#Override
protected Void doInBackground(String... arg0) {
try{
cursor = dbHelper.fetchAllWords();
}catch(Exception e){
e.printStackTrace();
}
return null;
}
#SuppressWarnings("deprecation")
#Override
protected void onPostExecute(final Void unused){
if(cursor != null){
if(dataAdapter == null){
startManagingCursor(cursor);
String[] columns = new String[] {
WordDbAdapter.KEY_WORD,
WordDbAdapter.KEY_ROWID,
};
int[] to = new int[] {
R.id.Word,
R.id.imgStar,
};
getListView().setTranscriptMode(ListView.TRANSCRIPT_MODE_NORMAL);
dataAdapter = new SimpleCursorAdapter(DictionaryActivity.this, R.layout.word_info, cursor, columns, to);
ListView listView = (ListView) findViewById(R.id.Diclist);
// Assign adapter to ListView
listView.setAdapter(dataAdapter);
}else{
dataAdapter.notifyDataSetChanged();
}
}
if(dialog != null && dialog.isShowing()){
dialog.dismiss();
}
isLoadingMore = false;
}
private AbsListView getListView() {
// TODO Auto-generated method stub
return null;
}
}
The adapter doesn't load everything at once, and that should not be the reason you're seeing poor performance. ListView and SimpleCursorAdapter are fully capable of scrolling a list of only 10,000 items. The adapter only loads items as the user scrolls through the list. From the code that you've posted, I would say that your performance issues come from
dbHelper.deleteAllWords();
dbHelper.insertSomeWords();
If you post the code for these methods and dbHelper.fetchAllWords(), perhaps we can offer more help. Additionally, you can solve user interface problems by executing these long running tasks on a background thread (check out AsyncTask) and using a ProgressDialog to inform the user what is going on.
Take a look at Endless Adapter from the great Mark Murphy. It makes it really easy. You'll have your dataset that contains just the items you're displaying. In the adapter you can then tell it to grab the next set from your database and add it to the dataset.