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How to get values from clicking listview item on Android? (NullException error)

I'm trying to retrieve the item name and quantity from my listview,
and display it onto the new class: Details.java.
Here are my codes for listview.java:
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_item);
//create items to display in customized listview (Arraylist)
displayiteminfo.add(new SalesItemInformationLV("Bread", 2));
displayiteminfo.add(new SalesItemInformationLV("Butter", 9));
displayiteminfo.add(new SalesItemInformationLV("Margarine", 8));
//New array adapter for customised ArrayAdapter
final ArrayAdapter<SalesItemInformationLV> adapter = new itemArrayAdapter(this, 0, displayiteminfo);
//displayiteminfo - the ArrayList of item objects to display.
//Find the list view, bind it with custom adapter
final ListView listView = (ListView)findViewById(R.id.customListview);
listView.setAdapter(adapter);
//Selecting the listview item!
listView.setOnItemClickListener(new AdapterView.OnItemClickListener() {
#Override
public void onItemClick(AdapterView<?> parent, View view, int position, long id) {
SalesItemInformationLV saleitem = (SalesItemInformationLV) listView.getSelectedItem();
String namevalue = saleitem.getItemname(); ---> WHERE ERROR OCCURS
int qtyvalue = saleitem.getItemquantity();
Intent myintent = new Intent(ListView.this, Details.class);
myintent.putExtra("itemname", namevalue);
myintent.putExtra("itemqty", qtyvalue);
startActivity(myintent);
}
});
}
//custom Arrayadapter
class itemArrayAdapter extends ArrayAdapter<SalesItemInformationLV>
{
private Context context;
private List<SalesItemInformationLV> item;
//constructor, call on creation
public itemArrayAdapter(Context context, int resource, ArrayList<SalesItemInformationLV> objects) {
//chaining to "default constructor" of ArrayAdapter manually
super(context, resource, objects);
this.context = context;
this.item = objects;
}
//called to render the list
public View getView(int position, View convertView, ViewGroup parent)
{
//get the item we are displaying
SalesItemInformationLV iteminfo = item.get(position);
//get the inflater and inflate the xml layout for each item
LayoutInflater inflater = (LayoutInflater) context.getSystemService(Activity.LAYOUT_INFLATER_SERVICE);
View view = inflater.inflate(R.layout.item_layout, null);
//Each component of the custom item_layout
TextView name = (TextView) view.findViewById(R.id.ItemNameSales);
TextView qty = (TextView)view.findViewById(R.id.ItemNameQty);
//set the name of item - access using an object!
name.setText(String.valueOf(iteminfo.getItemname()));
//set the quantity of item - access using an object!
qty.setText(String.valueOf(iteminfo.getItemquantity()));
return view;
//Now return to onCreate to use this cuztomized ArrayAdapter
}
}
Upon implementing the above codes, I got an error:
java.lang.NullPointerException: Attempt to invoke virtual method 'java.lang.String ... on a null object reference

Clicked and Selected are different things.
Replace
SalesItemInformationLV saleitem = (SalesItemInformationLV) listView.getSelectedItem();
with
SalesItemInformationLV saleitem = displayiteminfo.get(position)

Android: delete from database using index from listview - Can't access array of id's that is created with the view but not the basis for the list

I have a simple list view where each item is a view that has a title, from an ArrayList of strings and button, so that each entry in the ArrayList creates a new list item.
I also have another ArrayList of corresponding primary keys, which I want to use to delete specific items from an SQLite database but which isn't used in the list view(I don't want to display the ID's, but the strings that poplulate the list might not necessarily be unique so I can't use them to delete).
I have a onClick listener and method in the getView method for the list view, so that when someone clicks the delete button, I know the position in the list that the button was pressed in, so hopefully, I can then call a delete method on the database using id[position], however, I think due to the list view itself being created after the activity it's inside of, it can't resolve the id array, so I can't call delete.
public class TodayListActivity extends AppCompatActivity {
private ArrayList<String> names = new ArrayList<>();
FoodDB Db = null;
int deleteId;
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_todaylist);
ListView lv = (ListView) findViewById(R.id.today_meal_list);
Bundle a = this.getIntent().getExtras();
String[] id = a.getStringArray("idArray"); //used to delete
String[] mealNames = a.getStringArray("mealNamesArray"); //displayed
Collections.addAll(names, mealNames);
//call the list adapter to create views based off the array list 'names'
lv.setAdapter(new MyListAdapter(this, R.layout.list_item, names));
}
protected class MyListAdapter extends ArrayAdapter<String> {
private int layout;
private MyListAdapter(Context context, int resource, List<String> objects) {
super(context, resource, objects);
layout = resource;
}
#Override
public View getView(int position, View convertView, ViewGroup parent) {
viewHolder viewholder;
if (convertView == null) {
LayoutInflater inflater = LayoutInflater.from(getContext());
convertView = inflater.inflate(layout, parent, false);
viewholder = new viewHolder();
viewholder.title = (TextView) convertView.findViewById(R.id.report_meal_name);
viewholder.delButton = (Button) convertView.findViewById(R.id.button_delete_meal);
viewholder.delButton.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
int position = (Integer)v.getTag();
//int deleteId derived from id[position]
deleteId = Integer.parseInt(id[position]);
idToDelete(deleteId);
//update the list view to exclude the deleted item
names.remove(position);
notifyDataSetChanged();
}
});
convertView.setTag(viewholder);
} else {
viewholder = (viewHolder) convertView.getTag();
}
//set string value for title
viewholder.title.setText(getItem(position));
viewholder.delButton.setTag(position);
return convertView;
}
}
public class viewHolder {
TextView title;
TextView delButton;
}
//delete from database
public void idToDelete(int DeleteId){
Db.deleteFoods(deleteId);
}
}
Any suggestions as to how or where to get either the position index out of the list view (to the activity, where the id array is) or get access to the id array inside the listview would be appreciated!

You can pass the id array to the MyListAdapter adapter, by changing this class' constructor to accept it as a parameter. Also, you are already passing the names list as a parameter, you should keep a reference to it so you can access it when the button is pressed.
Here is an example:
protected class MyListAdapter extends ArrayAdapter<String> {
private int layout;
private List<String> names;
private String[] ids;
private MyListAdapter(Context context, int resource, List<String> names, String[] ids) {
super(context, resource, names);
layout = resource;
this.names = names;
this.ids = ids;
}
#Override
public View getView(final int position, View convertView, ViewGroup parent) {
...
viewholder.delButton.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
int deleteId = Integer.parseInt(ids[position]);// the "position" variable needs to be set to "final" in order to access it in here.
idToDelete(deleteId);
names.remove(position);
notifyDataSetChanged();
}
});
....
}
}
and here is how you can create an instance of this adapter:
lv.setAdapter(new MyListAdapter(this, R.layout.list_item, names, id));

Pull values from nested arrays

I have an array named societies:
List<Society> societies = new ArrayList<>();
That holds the following data:
[{"society_id":1,"name":"TestName1","email":"Test#email1","description":"TestDes‌​1"},
{"society_id":2,"name":"TestName2","email":"Test#email2","description":"TestD‌​es2"},
{"society_id":3,"name":"TestName3","email":"Test#email3","description":"Tes‌​tDes3"}}
I will be using this to populate a ListView but am having trouble writing the loop that will assign each array of values to its spot in the ListView.
I would like to find a way of pulling the values from the Array and assigning them to each list item by using a loop, can anybody help me with this?
My code (should be sufficient but if you need to see more please ask):
public class SocietySearch extends AppCompatActivity {
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_society_search);
List<Society> societies = new ArrayList<>();
ServerRequests serverRequest1 = new ServerRequests(SocietySearch.this);
serverRequest1.GetSocietyDataAsyncTask(societies, new GetSocietyCallback() {
#Override
public void done(List<Society> societies) {
ListView lv = (ListView) findViewById(R.id.ListView);
List<ListViewItem> items = new ArrayList<>();
items.add(new ListViewItem() {{
ThumbnailResource = R.drawable.test;
Title = societies.socName;
Subtitle = societies.socDes;
}});
CustomListViewAdapter adapter = new CustomListViewAdapter(SocietySearch.this, items);
lv.setAdapter(adapter);
}
});
}
class ListViewItem {
public int ThumbnailResource;
public String Title;
public String Subtitle;
}
Adapter Class:
public class CustomListViewAdapter extends ArrayAdapter {
LayoutInflater inflater;
List<SocietySearch.ListViewItem> items;
public CustomListViewAdapter(Activity context, List<SocietySearch.ListViewItem> items) {
super(context, R.layout.item_row);
this.items = items;
this.inflater = (LayoutInflater) context.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
}
#Override
public View getView(final int position, View convertView, ViewGroup parent) {
//Auto-generated method stub
ListViewItem item = items.get(position);
View vi = convertView;
if (convertView == null)
vi = inflater.inflate(R.layout.item_row, null);
ImageView test = (ImageView) vi.findViewById(R.id.imgThumbnail);
TextView txtTitle = (TextView) vi.findViewById(R.id.txtTitle);
TextView txtSubTitle = (TextView) vi.findViewById(R.id.txtSubTitle);
test.setImageResource(item.ThumbnailResource);
txtTitle.setText(item.Title);
txtSubTitle.setText(item.Subtitle);
return vi;
}
}

So we came to the conclusion, that we need to have the for loop to iterate through all the Society classes in the SocietySearch class:
#Override
public void done(List<Society> societies) {
ListView lv = (ListView) findViewById(R.id.ListView);
List<ListViewItem> items = new ArrayList<>();
for(Society s : societies) {
items.add(new ListViewItem() {{
ThumbnailResource = R.drawable.test;
Title = s.socName;
Subtitle = s.socDes;
}});
}
CustomListViewAdapter adapter = new CustomListViewAdapter(
SocietySearch.this, items);
lv.setAdapter(adapter);
}`
And we also had to fix the ArrayAdapter implementation:
public class CustomListViewAdapter extends ArrayAdapter {
LayoutInflater inflater;
List<SocietySearch.ListViewItem> items;
public CustomListViewAdapter(Activity context, List<SocietySearch.ListViewItem> items) {
super(context, R.layout.item_row, **items**); // the constructor
//needs the reference of the list, even though we use our variable to
//populate the rows. I guess it has to know how many elements it contains to
//iterate then through getView method, which is called for each row
this.items = items;
this.inflater = (LayoutInflater) context.getSystemService(
Context.LAYOUT_INFLATER_SERVICE);
}

Are you looking for a custom solution? So that you would bind each ListViewItem state to the corresponding column, then you have to create the custom solution like it is here. You would need to have a custom layout for each line and extend the ArrayAdapter where you bind each column for a line.
Is this what you want to know? If not, can you be more specific please.

You are creating an anonymous class and trying to assign values in it's object initializer. Object initializer doesn't have a reference to societies, that's why you are getting the compilation error. Try this instead:
class ListViewItem {
private final int ThumbnailResource;
private final String Title;
private final String Subtitle;
public ListViewItem(int thumbnail, String title, String subtitle) {
ThumbnailResource = thumbnail;
Title = title;
Subtitle = subtitle;
}
}
When adding list items:
items.add(new ListViewItem(R.drawable.test, societies.socName, societies.socDes);

ListView using BaseAdapter not showing in Activity

I'm trying to inflate a list using baseadapter within an activity. The list just doesn't inflate. From the logs implemented within the class, the getView() function doesn't even execute. Here's the code. -
public class CallLog extends Activity {
ListView logList;
List mList;
Context mCtx;
ArrayList<String> logName;
ArrayList<String> logNumber;
ArrayList<String> logTime;
#Override
protected void onCreate(Bundle savedInstanceState){
super.onCreate(savedInstanceState);
setContentView(R.layout.reject_call_log);
mCtx = getApplicationContext();
ListView logList = (ListView) findViewById(R.id.log_list);
mList = new List(mCtx, R.layout.log_row);
logList.setAdapter(mList);
SharedPreferences savedLogName = PreferenceManager.getDefaultSharedPreferences(mCtx);
SharedPreferences savedLogNumber = PreferenceManager.getDefaultSharedPreferences(mCtx);
SharedPreferences savedLogTime = PreferenceManager.getDefaultSharedPreferences(mCtx);
try{
logName = new ArrayList(Arrays.asList(TextUtils.split(savedLogName.getString("logName", null), ",")));
logNumber = new ArrayList(Arrays.asList(TextUtils.split(savedLogNumber.getString("logNumber", null), ",")));
logTime = new ArrayList(Arrays.asList(TextUtils.split(savedLogTime.getString("logTime", null), ",")));
Collections.reverse(logName);
Collections.reverse(logNumber);
Collections.reverse(logTime);
}catch(NullPointerException e){
e.printStackTrace();
//TextView noLog = (TextView)findViewById(R.id.no_log);
}
}
public class List extends BaseAdapter {
LayoutInflater mInflater;
TextView nameText;
TextView numberText;
TextView timeText;
int timePos = 1;
public List(Context context, int resource) {
}
#Override
public int getCount() {
return 0;
}
#Override
public Object getItem(int i) {
return null;
}
#Override
public long getItemId(int i) {
return 0;
}
#Override
public View getView(int position, View convertView, ViewGroup parent) {
View v = convertView;
if (convertView == null) {
v = mInflater.inflate(R.layout.row, null);
}
nameText = (TextView) v.findViewById(R.id.log_name);
numberText = (TextView) v.findViewById(R.id.log_number);
timeText = (TextView) v.findViewById(R.id.log_time);
nameText.setText(logName.get(position));
numberText.setText(logNumber.get(position));
timeText.setText(logTime.get(timePos) + logTime.get(timePos+1));
Log.d("RejectCall", "ListView");
timePos+=2;
return v;
}
}
}
Where is it all going wrong? Also, is there a better way to do what I'm trying to do?

Please replace the following code :
#Override
public int getCount() {
return 0;
}
with
#Override
public int getCount() {
return logName.size();
}
As list view only show the numbers of rows that is returned by this method and right now you are returning 0;
And after fetching the data in arraylist please use adapter.notifyDataSetChanged() to notify the list view.
You have to call notifyDataSetChanged() as you are filling data in array list after setting the adapter. so to notify the list view that data has been changed you have to call notify method(as above)

Your getItem() and getCount() haven't been implemented. If you want any kind of adapter to work for the list, these need to be implemented. Your list is also not holding any actual data, so getItem() has nothing to set.
Don't forget to call notifiyDataSetChanged() in your adapter after you set appropriate implementations for the above two functions.

Loading image from sqllite does not appear

I have an app that loads data from a sqllite database, then converts the data to appropriate formats so it could pass on the data to fragment tabs.
Everything works fine except for the images.
In the DB images are stored in full path, for example R.drawable.muntjakas and the images are available in the resource drawable folder.
The app pulls the data from the db and then converts it to int format so it could be passed on. Eclipse is not giving me any errors, but when the app loads images are not displayed. My xml files have the image id set up and displays the images if I assign the values manually for example
flag = new int[] { R.drawable.muntjakas,.... };
What's the problem?
fragmenttab1.java class that loads data from sql and converts it:
public class FragmentTab1 extends SherlockFragment {
ListView list;
ListViewAdapter adapter;
private static final String DB_NAME = "animalsDB.sqllite3";
private static final String TABLE_NAME = "animals";
private static final String ANIMAL_ID = "_id";
private static final String ANIMAL_NAME = "name";
private static final String ANIMAL_PIC = "pic";
public static final String[] ALL_KEYS = new String[] {ANIMAL_ID, ANIMAL_NAME,ANIMAL_PIC };
private SQLiteDatabase database;
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
View rootView = inflater.inflate(R.layout.fragmenttab1, container,
false);
ExternalDbOpenHelper dbOpenHelper = new ExternalDbOpenHelper(getActivity(), DB_NAME);
database = dbOpenHelper.openDataBase();
Cursor cursor = getAllRows();
ArrayList<String> nameArray = new ArrayList<String>();
ArrayList<Integer> picArray = new ArrayList<Integer>();
for(cursor.moveToFirst(); cursor.moveToNext(); cursor.isAfterLast()) {
nameArray.add(cursor.getString(cursor.getColumnIndex(ANIMAL_NAME)));
picArray.add(cursor.getInt(cursor.getColumnIndex(ANIMAL_PIC)));
}
final String[] name = (String[]) nameArray.toArray(new String[nameArray.size()]);
final Integer[] pic = (Integer[]) picArray.toArray(new Integer[picArray.size()]);
final int[] flag = new int[pic.length];
for (int i = 0; i < pic.length; i++ ) {
flag[i] = pic[i];
}
// Locate the ListView in fragmenttab1.xml
list = (ListView) rootView.findViewById(R.id.listview);
// Pass results to ListViewAdapter Class
adapter = new ListViewAdapter(getActivity(), name, flag);
// Binds the Adapter to the ListView
list.setAdapter(adapter);
// Capture clicks on ListView items
list.setOnItemClickListener(new OnItemClickListener() {
#Override
public void onItemClick(AdapterView<?> parent, View view,
int position, long id) {
// Send single item click data to SingleItemView Class
Intent i = new Intent(getActivity(), SingleItemView.class);
// Pass all data country
i.putExtra("country", name);
// Pass all data flag
i.putExtra("flag", flag);
// Pass a single position
i.putExtra("position", position);
// Open SingleItemView.java Activity
startActivity(i);
}});
return rootView;
}
public Cursor getAllRows() {
String where = null;
Cursor c = database.query(true, TABLE_NAME, ALL_KEYS,
where, null, null, null, null, null);
if (c != null) {
c.moveToFirst();
}
return c;
}
}
My listViewAdapter.java class that should load the data on the screen:
package kf.kaunozoo;
public class ListViewAdapter extends BaseAdapter {
// Declare Variables
Context context;
String[] country;
int[] flag;
LayoutInflater inflater;
public ListViewAdapter(Context context, String[] country, int[] flag) {
this.context = context;
this.country = country;
this.flag = flag;
}
public int getCount() {
return country.length;
}
public Object getItem(int position) {
return null;
}
public long getItemId(int position) {
return 0;
}
public View getView(int position, View convertView, ViewGroup parent) {
// Declare Variables
TextView txtcountry;
ImageView imgflag;
inflater = (LayoutInflater) context
.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
View itemView = inflater.inflate(R.layout.listview_item, parent, false);
// Locate the TextViews in listview_item.xml
txtcountry = (TextView) itemView.findViewById(R.id.country);
// Locate the ImageView in listview_item.xml
imgflag = (ImageView) itemView.findViewById(R.id.flag);
// Capture position and set to the TextViews
txtcountry.setText(country[position]);
// Capture position and set to the ImageView
imgflag.setImageResource(flag[position]);
return itemView;
}
}
What am I doing wrong? All answers are appreciated

I have had this problem once in one of my apps, however, what I did was, I saved unique ids for each drawable in database as I had limited images. While displaying I wrote a small function where I used switch statement to check for each id from database and then loaded images accordingly in ImageView.
However, when you have lots of images, try to use below function, where you can provide image names dynamically from database.
// image from res/drawable
int resID = getResources().getIdentifier("your_image_name",
"drawable", getPackageName());
Also, you may try the solution given at this blog.