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how to delete a specific item from table in database?

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});

How to load current item information if it is being clicked from listview

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");.

How to retrieve data from specific row SQLiteAssetHelper

how to retrieve specific data by their Id and display them in textview? instead of retrieving the data and display all the data in listview. please help!
public class KaikaiProfileActivity extends ListActivity {
private Cursor animals;
private MyDatabase db;
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
db = new MyDatabase(this);
animals = db.getAnimals(); // you would not typically call this on the main thread
ListAdapter adapter = new SimpleCursorAdapter(this,
android.R.layout.simple_list_item_2,
animals,
new String[] {"animalName","animalPersonality"},
new int[] {android.R.id.text1, android.R.id.text2});;
getListView().setAdapter(adapter);
}
#Override
protected void onDestroy() {
super.onDestroy();
animals.close();
db.close();
}
// retrieve all data
how to retrieve the data from specific row?
public Cursor getAnimals() {
SQLiteDatabase db = getReadableDatabase();
SQLiteQueryBuilder qb = new SQLiteQueryBuilder();
String [] sqlSelect = {"0_id", "animalName", "animalInfo","ImageName","animalGender","animalDOB",
"animalDOB", "animalBirthPlace", "animalPersonality", "animalFeatures", "animalFood", "animalPastTime"
};
String sqlTables = "AnimalInfo";
qb.setTables(sqlTables);
Cursor c = qb.query(db, sqlSelect, null, null,
null, null, null);
c.moveToFirst();
return c;
}

use c.moveToPosition(int index) in place of c.moveToFirst() to get record at that particular index
For example, if you want to return first record, use c.moveToPosition(0), for second record use c.moveToPosition(1) and so on
If you want to retrieve by column value then use qb.appendWhere("<colname>=<value>") ;

Listview using Endless adapter

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.

Set bind view in simple adapter?

I want to setup view binder in simple adapter to show photos from contacts, however I set two text view's with name and number with Hash Map, so third value is Image View where I want to put contact photo corresponding to contact ID.
Thank you in advance, Wolf.
Here is my code :
ArrayList<HashMap<String, String>> mapa = new ArrayList<HashMap<String, String>>();
ContentResolver cr = getContentResolver();
Cursor cur = cr.query(ContactsContract.Contacts.CONTENT_URI, null, null, null, null);
if(cur.getCount() > 0){
while(cur.moveToNext()){
id = cur.getString(cur.getColumnIndex(ContactsContract.Contacts._ID));
String photoUri = cur.getString(cur.getColumnIndex(ContactsContract.Contacts.PHOTO_ID));
if(Integer.parseInt(cur.getString(cur.getColumnIndex(ContactsContract.Contacts.HAS_PHONE_NUMBER))) > 0){
final Cursor numCur = cr.query(ContactsContract.CommonDataKinds.Phone.CONTENT_URI, null, ContactsContract.CommonDataKinds.Phone.CONTACT_ID + " = ?", new String[]{id}, null);
for(numCur.moveToFirst(); !numCur.isAfterLast(); numCur.moveToNext()){
brTel = numCur.getString(numCur.getColumnIndex(ContactsContract.CommonDataKinds.Phone.NUMBER));
ime = cur.getString(cur.getColumnIndex(ContactsContract.Contacts.DISPLAY_NAME));
tmpIme = new String[] {ime};
for(int i = 0; i < tmpIme.length; i++){
HashMap<String, String> imeMapa = new HashMap<String, String>();
imeMapa.put("imeLista", ime);
imeMapa.put("checkBox", photoUri);
imeMapa.put("Mobilni", brTel);
mapa.add(imeMapa);
}
}
numCur.close();
}
} // While
}
SimpleAdapter sa = new SimpleAdapter(getApplicationContext(), mapa, R.layout.imenik, new String[] {"imeLista", "checkBox", "Mobilni"}, new int[] {R.id.tvImeImenik, R.id.cbOznaci, R.id.tvSamoProba});
sa.setViewBinder(simpleSlika);
lImenik.setAdapter(sa);
and my view binder is :
private final SimpleAdapter.ViewBinder simpleSlika = new SimpleAdapter.ViewBinder() {
public boolean setViewValue(View view, Object data,
String textRepresentation) {
if (view instanceof ImageView && data instanceof Bitmap) {
ImageView v = (ImageView)view;
v.setImageBitmap((Bitmap)data);
// return true to signal that bind was successful
return true;
}
return false;
}
};
but it's not working.
Help please???

Yes its possible, you just create your own adapter (extends BaseAdapter), override getView method and there add bitmap to imageview.
public ContactAdapter(Activity a,ArrayList<Object> list)
{
activity = a;
inflater = (LayoutInflater)activity.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
}
#Override
public View getView(final int position, View convertView, ViewGroup parent)
{
View v=convertView;
if(convertView==null)
v = inflater.inflate(R.layout.contact, null);
ImageView image = (ImageView)v.findViewById(R.id.img);
}
Something like this. You have to extends this.
Check also : Lazy load of images in ListView