Develop Reference

adapter.notifyItemChanged(position) has no effect

For each item of the list ("itemList")
ArrayList<Item> itemList = new ArrayList<>();
shown by "recyclerView" that is controlled by "itemAdapter", its quantity is displayed, as well as a plus and minus button which allows the user to respectively increase and decrease the quantity.
In the set-up of "itemAdapter" these buttons are given functionality by:
itemAdapter.setOnItemClickListener(new ItemAdapter.OnItemClickListener() {
#Override
public void onPlusClick(int position) {
itemList.get(position).setQuantity(itemList.get(position).getQuantity() + 1);
itemAdapter.notifyItemChanged(position);
Log.d(TAG, "onPlusClick: position = " + position + " quantity = " + itemList.get(position).getQuantity());
}
#Override
public void onMinusClick(int position) {
itemList.get(position).setQuantity(itemList.get(position).getQuantity() - 1);
if (itemList.get(position).getQuantity() < 1) {
itemList.get(position).setQuantity(1);
}
itemAdapter.notifyItemChanged(position);
Log.d(TAG, "onMinusClick: position = " + position + " quantity = " + itemList.get(position).getQuantity());
}
})
The display of the quantity is set up in the onBindViewHolder() of the adapter class ItemAdapter with:
holder.textviewQuantity.setText(String.valueOf(currentItem.getQuantity()));
And this is the code for the adapter class
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.Button;
import android.widget.ImageView;
import android.widget.TextView;
import androidx.annotation.NonNull;
import androidx.cardview.widget.CardView;
import androidx.recyclerview.widget.RecyclerView;
import java.util.ArrayList;
public class ItemAdapter extends RecyclerView.Adapter<ItemAdapter.ItemListHolder> {
private ArrayList<Item> mItemList;
private OnItemClickListener mListener;
public interface OnItemClickListener {
void onPlusClick(int position);
void onMinusClick(int position);
}
public void setOnItemClickListener(OnItemClickListener listener) {
mListener = listener;
}
#NonNull
#Override
public ItemListHolder onCreateViewHolder(#NonNull ViewGroup parent, int viewType) {
View v = LayoutInflater.from(parent.getContext()).inflate(R.layout.item, parent, false);
return new ItemListHolder(v, mListener);
}
#Override
public void onBindViewHolder(#NonNull ItemListHolder holder, int position) {
Item currentItem = mItemList.get(position);
holder.imageviewCategoryIcon.setImageResource(Main.getIconID(currentItem.getCategoryNumber()));
holder.textviewItemName.setText(currentItem.getItemName());
holder.textviewQuantity.setText(String.valueOf(currentItem.getQuantity()));
}
}
#Override
public int getItemCount() {
return mItemList.size();
}
public static class ItemListHolder extends RecyclerView.ViewHolder {
CardView cardviewItem;
ImageView imageviewCategoryIcon;
TextView textviewItemName;
Button buttonPlus;
Button buttonMinus;
TextView textviewQuantity;
public ItemListHolder(#NonNull View view, OnItemClickListener listener) {
super(view);
cardviewItem = view.findViewById(R.id.cardview_item);
imageviewCategoryIcon = view.findViewById(R.id.imageview_category_icon);
textviewItemName = view.findViewById(R.id.textview_item_name);
buttonPlus = view.findViewById(R.id.button_plus);
buttonMinus = view.findViewById(R.id.button_minus);
buttonPlus.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
if (listener != null) {
int position = getBindingAdapterPosition();
if (position != RecyclerView.NO_POSITION) {
listener.onPlusClick(position);
}
}
}
});
buttonMinus.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
if (listener != null) {
int position = getBindingAdapterPosition();
if (position != RecyclerView.NO_POSITION) {
listener.onMinusClick(position);
}
}
}
});
}
}
public ItemAdapter(ArrayList<Item> itemList) {
mItemList = itemList;
}
}
When the app starts up, the list of items is displayed, with each item showing the correct quantity.
But when the user clicks a plus or minus button, the quantity displayed doesn't change, though the logs clearly indicate the correct position in "itemList" has been chosen, and that the quantity of the corresponding item has indeed changed correctly.
It looks like itemAdapter.notifyItemChanged(position) has no effect. I also tried itemAdapter.notifyDataSetChanged(), but with no effect either. The recycler display is not being refreshed with the data changes.
What could be wrong?
PS: my very unworkable workaround is to run the whole recycler set-up each time that plus or minus button is clicked. Works fine if the list of items is no longer than the screen, but of course, resets to the top of the list if you press a button of an item that was found scrolling down.

This is an answer by the author.
The problem could ultimately be narrowed down to itemAdapter.notifyDataSetChanged() stalling when the entire "itemList" has been changed, like with a for loop. Also itemAdapter.notifyItemChanged() then become irresponsive. As workaround, I have everywhere replaced itemAdapter.notifyDataSetChanged() with setUpRecycler(), an own-defined method that sets up the whole RecyclerView again. Inevitably, the view will go to the top of the list, but that's a quirk I'm (gladly) prepared to accept. itemAdapter.notifyItemChanged() works fine then.

android listview check on long press with custom adapter

I did not find any right solutions for my case on the internet.
I have a couple of items from a database in my listview object. For this I created a custom BaseAdapter and implemented a OnLongClickListener() inside the adapter class (I know that I would overwrite how a listview handle the animations etc. but this is just for learning).
I can select multiple items with a long click and change the background color of each of the rows. But I can not reset the rows (unchecked and "normal" background color) although I implemented these behaviors in my listener.
What am I doing wrong?
Here is my custom adapter class
package com.dacmas.shoppingapp;
import android.content.Context;
import android.text.AndroidCharacter;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.BaseAdapter;
import android.widget.CheckBox;
import android.widget.CompoundButton;
import android.widget.ImageView;
import android.widget.ListView;
import android.widget.TextView;
import com.amulyakhare.textdrawable.TextDrawable;
import com.amulyakhare.textdrawable.util.ColorGenerator;
import java.util.ArrayList;
import java.util.List;
public class ShoppingListAdapter extends BaseAdapter {
private ArrayList< ShoppingListEntry > m_itemList;
private Context m_context;
private LayoutInflater m_inflater;
private View m_convertView;
public ShoppingListAdapter(Context context, ArrayList< ShoppingListEntry > shoppingListEntryArrayList ) {
m_itemList = shoppingListEntryArrayList;
m_context = context;
m_inflater = ( LayoutInflater.from( context ) );
}
#Override
public int getCount() { return m_itemList.size(); }
#Override
public Object getItem( int position ) { return m_itemList.get( position ); }
#Override
public long getItemId( int position ) { return position; }
#Override
public View getView(final int position, View convertView, final ViewGroup parent ) {
if ( convertView == null ) {
m_convertView = LayoutInflater.from( m_context ).inflate( R.layout.list_row_shoppinglist, parent, false );
}
ImageView accountImage = (ImageView) m_convertView.findViewById(R.id.text_drawable);
String firstLetterOfName = "A";
ColorGenerator generator = ColorGenerator.MATERIAL;
int color = generator.getRandomColor();
TextDrawable drawable = TextDrawable.builder()
.buildRound(firstLetterOfName, color);
accountImage.setBackground(drawable);
TextView title = ( TextView ) m_convertView.findViewById( R.id.txt_title );
TextView info = ( TextView ) m_convertView.findViewById( R.id.txt_info );
String itemTitle;
String productBrand = m_itemList.get( position ).getProductBrand().toString();
if ( !productBrand.isEmpty() ) {
itemTitle = productBrand + " " + m_itemList.get( position ).getProductName().toString();
} else {
itemTitle = m_itemList.get( position ).getProductName().toString();
}
title.setText( itemTitle );
String itemInfo;
String productAmount = m_itemList.get( position ).getProductAmount();
itemInfo = productAmount;
info.setText( itemInfo );
m_convertView.setOnLongClickListener(new View.OnLongClickListener() {
#Override
public boolean onLongClick(View v) {
if ( ((ListView)parent).isItemChecked(position) ) {
( ( ListView )parent ).setItemChecked( position, false );
v.setBackgroundColor(m_convertView.getResources().getColor(R.color.colorWhite));
} else {
( ( ListView )parent ).setItemChecked( position, true );
v.setBackgroundColor(m_convertView.getResources().getColor(R.color.colorSelectedItem));
}
return false;
}
});
return m_convertView;
}
}

The question is - When do you want the deselection to happen?
Ideally, once you perform a long press, you enter in to a single selection mode. From that point on wards, it should handle clicks (touches) to toggle selection (and optionally change color)
Now that you are done with your selection choices, you may want to
Perform an action like deleting the selected items.
Wait for some other action to exit the selection mode.
In case of option two, trapping the back button press(onBackPressed) might do the trick. in that you can write your logic clear all selections (color and check box)
It might be a good idea if you can bake that logic into your custom adapter for purposes of re-usability.

How to make ListView to show only the 6 last items?

I have Activity that shows only listview (He pulls the data from SQLite database), There is no limit for the data he can shows, and it work out well.
Now, I want to add a new little listview to the MainActivity which will show only the last five of the data.
I could not find anywhere on the network how to do it..
DataListActivity.java
package com.example.ido.grades;
import android.content.Intent;
import android.database.Cursor;
import android.database.sqlite.SQLiteDatabase;
import android.support.v7.app.ActionBarActivity;
import android.os.Bundle;
import android.view.ContextMenu;
import android.view.MenuInflater;
import android.view.MenuItem;
import android.view.View;
import android.widget.AdapterView;
import android.widget.ListView;
import android.widget.Toast;
public class DataListActivity extends ActionBarActivity {
ListView listView;
SQLiteDatabase sqLiteDatabase;
CourseDbHelper courseDbHelper;
Cursor cursor;
ListDataAdaptar listDataAdaptar;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.update_course);
hideActionBar();
listView = (ListView) findViewById(R.id.list_view);
listDataAdaptar = new ListDataAdaptar(getApplicationContext(),R.layout.row_layout);
listView.setAdapter(listDataAdaptar);
registerForContextMenu(listView);
courseDbHelper = new CourseDbHelper(getApplicationContext());
sqLiteDatabase = courseDbHelper.getReadableDatabase();
cursor = courseDbHelper.getInformation(sqLiteDatabase);
registerForContextMenu(listView);
if (!cursor.moveToFirst()){
}
else {
do {
String year,semester,course,points,grade;
year = cursor.getString(0);
semester = cursor.getString(1);
course = cursor.getString(2);
points = cursor.getString(3);
grade = cursor.getString(4);
DataProvider dataProvider = new DataProvider(year,semester,course,points,grade);
listDataAdaptar.add(dataProvider);
}
while (cursor.moveToNext());
}
}
public void onCreateContextMenu(ContextMenu menu, View v, ContextMenu.ContextMenuInfo menuInfo) {
MenuInflater inflater = getMenuInflater();
inflater.inflate(R.menu.menu_data_list, menu);
}
public boolean onContextItemSelected(MenuItem item) {
AdapterView.AdapterContextMenuInfo info =
(AdapterView.AdapterContextMenuInfo) item.getMenuInfo();
int mySelectedRowIndex = info.position;
switch (item.getItemId()) {
case R.id.update_item:
courseDbHelper = new CourseDbHelper(getApplicationContext());
sqLiteDatabase = courseDbHelper.getReadableDatabase();
DataProvider raw2 = (DataProvider)listDataAdaptar.getItem(mySelectedRowIndex);
Intent i = new Intent(DataListActivity.this, UpdateCourseActivity.class);
String year = raw2.getYear();
String semester = raw2.getSemester();
String course = raw2.getCourse();
String points = raw2.getPoints();
String grade = raw2.getGrade();
int semIndex;
if (semester.equals("A'")){
semIndex =1;
}
else if (semester.equals("B'")){
semIndex =2;
}
else{
semIndex=3;
}
i.putExtra("YEAR", year);
i.putExtra("SEMESTER", Integer.toString(semIndex));
i.putExtra("COURSE", course);
i.putExtra("POINTS", points);
i.putExtra("GRADE", grade);
i.putExtra("POS", Integer.toString(mySelectedRowIndex));
startActivity(i);
return true;
case R.id.delete_item:
courseDbHelper = new CourseDbHelper(getApplicationContext());
sqLiteDatabase = courseDbHelper.getReadableDatabase();
DataProvider raw = (DataProvider)listDataAdaptar.getItem(mySelectedRowIndex);
courseDbHelper.deleteInformation(raw.getYear(), raw.getSemester(), raw.getCourse(), raw.getPoints(), raw.getGrade());
Toast.makeText(this,"delete, pos["+mySelectedRowIndex+"]",Toast.LENGTH_LONG).show();
finish();
startActivity(getIntent());
return true;
default:
return super.onOptionsItemSelected(item);
}
}
public void onBackPressed() {
startActivity(new Intent(this, MainActivity.class));
}
private void hideActionBar() {
//Hide the action bar only if it exists
if (getSupportActionBar() != null) {
getSupportActionBar().hide();
}
}
}
ListDataAdapter.java
package com.example.ido.grades;
import android.content.Context;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.ArrayAdapter;
import android.widget.TextView;
import java.util.ArrayList;
import java.util.List;
/**
* Created by Ido on 08/08/2015.
*/
public class ListDataAdaptar extends ArrayAdapter{
List list = new ArrayList();
public ListDataAdaptar(Context context, int resource) {
super(context, resource);
}
static class LayoutHandler{
TextView YEAR,SEMESTER,COURSE,POINTS,GRADE;
}
#Override
public void add(Object object) {
super.add(object);
list.add(object);
}
#Override
public int getCount() {
return list.size();
}
#Override
public Object getItem(int position) {
return list.get(position);
}
#Override
public View getView(int position, View convertView, ViewGroup parent) {
View row = convertView;
LayoutHandler layoutHandler;
if (row == null){
LayoutInflater layoutInflater = (LayoutInflater) this.getContext().getSystemService(Context.LAYOUT_INFLATER_SERVICE);
row = layoutInflater.inflate(R.layout.row_layout,parent,false);
layoutHandler = new LayoutHandler();
layoutHandler.YEAR = (TextView)row.findViewById(R.id.textYear);
layoutHandler.SEMESTER = (TextView)row.findViewById(R.id.textSemester);
layoutHandler.COURSE = (TextView)row.findViewById(R.id.textCourse);
layoutHandler.POINTS = (TextView)row.findViewById(R.id.textPoints);
layoutHandler.GRADE = (TextView)row.findViewById(R.id.textGrade);
row.setTag(layoutHandler);
}
else{
layoutHandler = (LayoutHandler) row.getTag();
}
DataProvider dataProvider = (DataProvider) this.getItem(position);
layoutHandler.YEAR.setText(dataProvider.getYear());
layoutHandler.SEMESTER.setText(dataProvider.getSemester());
layoutHandler.COURSE.setText(dataProvider.getCourse());
layoutHandler.POINTS.setText(dataProvider.getPoints());
layoutHandler.GRADE.setText(dataProvider.getGrade());
return row;
}
}

You can move to the last position of your current cursor and move to previous rows getting required data. Sort of:
ArrayList string;
if (cursor.moveToLast()){
for (int i = 1; i<=6; i++) {
string.add(cursor.getString(cursor.getColumnIndex("your_data")));
cursor.moveToPrevious();
}
}
cursor.close();
The result will be ArrayList with last 6 strings of your cursor data. You can feed it to the new ArrayAdapter and show it on the screen.
Instead of ArrayList you can create another cursor as well with all existing data and feed it to already existing adapter for example as it's described here:
https://stackoverflow.com/a/18290921/4890659

Ignoring your code, you obviously have an Array of Objects your passing into the constructor of your Array Adapter.
Object[] data = new Object[]{...}
MyArrayAdapter myAdapter = new MyArrayAdapter(data ,... else)
You simply get this data array and append the last 6 elements to a new array.
Object[] data2 = new Object[6]
for(int i = data.length()-7; i<data.length(); i++){
data2[data.length()-i] = data[i]
Then create a new Adapter passing the new data2 array.
MyArrayAdapter myAdapter = new MyArrayAdapter(data2, ... else)

Create method that will return the last 6 rows i cursor [SQL query].
cursor = courseDbHelper.getInformationLast_6(sqLiteDatabase);
SQL:
SELECT * FROM table ORDER BY column DESC [ASC] LIMIT 6;

by this you can get 6 items in your list. Try with following code in your adapter class.
public int getCount() {
return 6;
}
than change your query to limit 6 by ascending order or descending order.

Saved item's state in simple list item

I am a new android developer and I need your help. I created a simple listview. User can add some item in listview (type in EditText and click on Button "OK"). When user made onItemClick , the app will strike out text and set background green.
But then , when I add one more item,I see that it applies that strike out and background option from previously item.
Can you advise me what I need to do in this situation? How to improve it?
package com.example.boytsov.foodbasketapp;
import android.app.Activity;
import android.graphics.Color;
import android.os.Bundle;
import android.util.Log;
import android.view.KeyEvent;
import android.view.View;
import android.view.inputmethod.EditorInfo;
import android.widget.AdapterView;
import android.widget.ArrayAdapter;
import android.widget.Button;
import android.widget.EditText;
import android.widget.ListView;
import android.widget.TextView;
import android.widget.Toast;
import java.util.ArrayList;
import java.util.List;
/**
* Created by Boytsov on 23.07.2015.
*/
public class ProductList extends Activity implements View.OnClickListener,AdapterView.OnItemClickListener,AdapterView.OnItemLongClickListener,TextView.OnEditorActionListener {
EditText myText;
ListView lvMain;
ArrayList<String> catnames;
ArrayAdapter<String> adapter;
Button button;
DataBase db;
final String LOG_TAG = "myLogs";
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.productlist);
db = new DataBase(this);
myText = (EditText)findViewById(R.id.editText);
lvMain = (ListView) findViewById(R.id.lvMain);
button=(Button)findViewById(R.id.button);
catnames= new ArrayList<String>();
// создаем адаптер
adapter = new ArrayAdapter<String>(this,
android.R.layout.simple_list_item_1, catnames);
// присваиваем адаптер списку
lvMain.setAdapter(adapter);
lvMain.setOnItemClickListener(this);
lvMain.setOnItemLongClickListener(this);
// Прослушиваем нажатия клавиш
button.setOnClickListener(this);
//слушаем edittext
myText.setOnEditorActionListener(this);
}
#Override
public void onClick(View view) {
switch (view.getId()){
case R.id.button : {
//TextView myText = (TextView) view;
catnames.add(0, myText.getText().toString());
adapter.notifyDataSetChanged();
//myText.setBackgroundColor(Color.TRANSPARENT);
//myText.setPaintFlags(0);
Log.d("Insert: ", "Inserting ..");
db.addProduct(new Product(myText.getText().toString()));
myText.setText("");
Log.d("Reading: ", "Reading all contacts..");
List<Product> products = db.getAllProducts();
for (Product cn : products) {
String log = "Id: "+cn.getID_product()+" ,Name: " + cn.getName_product();
// Writing Contacts to log
Log.d("Name: ", log);
}
}
break;
}
}
#Override
public void onItemClick(AdapterView<?> adapterView, View view, int i, long l) {
TextView textview= (TextView) view;
if (textview.getPaintFlags() != 16){
textview.setPaintFlags(16);
textview.setBackgroundColor(Color.parseColor("#77dd77"));
Toast.makeText(this, "Куплено", Toast.LENGTH_SHORT).show();
adapter.notifyDataSetChanged();
Log.d(LOG_TAG, "itemClick: position = " + i + ", id = "
+ l);
} else {
textview.setPaintFlags(0);
textview.setBackgroundColor(Color.TRANSPARENT);
Toast.makeText(this, "Не куплено", Toast.LENGTH_SHORT).show();
}
}
#Override
public boolean onItemLongClick(AdapterView<?> parent, View view, int position, long id) {
catnames.remove(position);
adapter.notifyDataSetChanged();
Toast.makeText(this, "Удалено", Toast.LENGTH_SHORT).show();
Log.d(LOG_TAG, "onItemClick: position = " + position + ", id = "
+ id);
return true;
}
#Override
public boolean onEditorAction(TextView v, int actionId, KeyEvent event) {
boolean handled = false;
if (actionId == EditorInfo.IME_ACTION_SEND) {
Log.d(LOG_TAG, "onItemClick: position = " + actionId + ", id = "
+ event);
handled = true;
}
return handled;
}
}

You apply your changes on the view at position 0.
When you add your item you also add it to position 0, hence the entire list is pushed down by 1 and the new item get the already changed view.
Edited Answer
Sorry, I was short on time, but now I can address it more thoroughly.
One important thing you must understand is that the view which shows your data in the list view DOES NOT NECESSARILY correspond with your data.
If you click on an item in your list and change it's views attributes, it doesn't change the state for the item or object which represents the data, but the view itself.
For example if you click on item at position 0 it will change the view's background at position 0. Then, in your example, you add an item at the top of the list, which puts the newly created object at position 0 (with the already modified view) and pushes THE REST OF THE ALREADY CREATED DATA by one, And you end up with an already changed view at position 0 with new data at position 0.
What you should do is as follows:
1)Make sure your object has a boolean member which states if item is "strike out" or not. like for example mIsStrikeOut.
2)create a custom adapter from any android adapter, like from ArrayAdapter.
3)Override it's getView method, for example:
#Override
public View getView(int position, View convertView, ViewGroup parent)
{
View view = convertView;
if (view == null)
{
view = (LinearLayout) inflater.inflate(R.layout. simple_list_item_1, parent, false);
}
TextView textview = (TextView) view.findViewById(R.id.text1);
if (catnames.get(position).isStrikeOut())
{
textview.setPaintFlags(16);
textview.setBackgroundColor(Color.parseColor("#77dd77"));
Toast.makeText(this, "Куплено", Toast.LENGTH_SHORT).show();
Log.d(LOG_TAG, "itemClick: position = " + i + ", id = "
+ l);
}
else
{
textview.setPaintFlags(0);
textview.setBackgroundColor(Color.TRANSPARENT);
Toast.makeText(this, "Не куплено", Toast.LENGTH_SHORT).show();
}
return view;
}
Side note:
When you query your data from your DB make sure the order is correct, I would suggest ORDER BY id dec or something like that.

I do not really know if this is the right answer but it is a suggestion :
#Override
public void onClick(View view) {
switch (view.getId()){
case R.id.button : {
//TextView myText = (TextView) view;
catnames.add(0, myText.getText().toString());
View view = listView.getChildAt(0);
TextView textview= (TextView) view;
textview.setBackgroundColor(Color.TRANSPARENT);
adapter.notifyDataSetChanged();
//myText.setBackgroundColor(Color.TRANSPARENT);
//myText.setPaintFlags(0);
Log.d("Insert: ", "Inserting ..");
db.addProduct(new Product(myText.getText().toString()));
myText.setText("");
Log.d("Reading: ", "Reading all contacts..");
List<Product> products = db.getAllProducts();
for (Product cn : products) {
String log = "Id: "+cn.getID_product()+" ,Name: " + cn.getName_product();
// Writing Contacts to log
Log.d("Name: ", log);
}
}
break;
}
}

How to mark views in a ListView?

I have an app with a list view. The listview works fine. The problem starts, when I want the list to start with some of the rows marked. I can mark a row, if I press on it. But, don't seem to find a way to mark any row on initialization.
This is my code:
listViewOfBluetooth = getListView();
setInitialEnabledDevices();
listViewOfBluetooth.setOnItemClickListener(new OnItemClickListener() {
public void onItemClick(AdapterView<?> parent, View view, int position, long id) {
String chosenBluetoothDevice = (String) ((TextView) view).getText();
BluetoothEnableOrDisable(view, chosenBluetoothDevice);
Toast.makeText(getApplicationContext(), chosenBluetoothDevice, Toast.LENGTH_SHORT).show();
editor.putString("bluetooth_name_from_list1", chosenBluetoothDevice);
editor.putBoolean("have_the_cars_bluetooth", true);
editor.commit();
Intent intent = new Intent(List.this, ParkOGuardActivity.class);
startActivity(intent);
}
});
}
public static void setInitialEnabledDevices(){
int length = listViewOfBluetooth.getChildCount();
View view = null;
String first = prefs.getString("bluetooth_name_from_list0", "");
String second = prefs.getString("bluetooth_name_from_list1", "");
String third = prefs.getString("bluetooth_name_from_list2", "");
for(int i = 0; i < length; i++){
view = listViewOfBluetooth.getChildAt(i);
if(view.equals(first) || view.equals(second) || view.equals(third)) {
view.setBackgroundColor(Color.GRAY);
}
}
}
How can I fix it?
Thanks!

You can achive this by using custom adapter. Here is the workaround.
Initialize your custom adapter
Add some flag for marked device names.
Override the getView() & check for the flag. And set the background of the list item accordingly.
Reply if you don't get it or face any complexity.
Update:
Here is a sample adapter. I didn't compile the code. So there might be some errors.
import java.util.ArrayList;
import android.content.Context;
import android.graphics.Color;
import android.view.View;
import android.view.ViewGroup;
import android.widget.BaseAdapter;
import android.widget.TextView;
public class TestAdapter extends BaseAdapter
{
ArrayList<String> deviceNames;
ArrayList<Boolean> selected;
Context context;
public TestAdapter(Context context)
{
this.context = context;
deviceNames = new ArrayList<String>();
selected = new ArrayList<Boolean>();
}
public void addDeviceToList(String deviceName, boolean isSelected)
{
deviceNames.add(deviceName);
selected.add(isSelected);
notifyDataSetChanged();
}
public int getCount()
{
return deviceNames.size();
}
public Object getItem(int position)
{
return deviceNames.get(position);
}
public long getItemId(int position)
{
return position;
}
public View getView(int position, View convertView, ViewGroup parent)
{
TextView tv = new TextView(context);
tv.setText(deviceNames.get(position));
if(selected.get(position) == true)
{
tv.setBackgroundColor(Color.parseColor("#ff0000"));
}
return tv;
}
}
Now create adapter object and set the adapter to listView. And add single item by calling addDeviceToList() method.

That seems to nasty
but i think you want to modify the views inside listview before loading it
The thing is, that your list won't have children as long as the list is not displayed to the user.so you may not modify the view before showing it to the user
But if you really need to communicate with the views on a such low level you could try to attach a scroll listener to your list:
#Override
public void onScroll(AbsListView view, int firstVisibleItem, int visibleItemCount, int totalItemCount) {
for (int i = 0; i < visibleItemCount; i++) {
View child = getChildAt(i);
Now edit this view
}
}