Develop Reference

ListView updates the entry only when the application is restarted again

In this application, I have a listview and a sqlitedatabase. There is a floating action button which on clicking displays a dialog box containing two edittext one for name and another for number. The problem is that the after clicking on the add option of the dialog box the entry is not shown on the listview. But when the activity is destroyed and onCreate is called again on the activity , the entry is shown.
I tried using adapter.notifyDataSetChanged() but it doesn't work. The code is shown below :
Code
public class DetailsActivity extends AppCompatActivity {
private DatabaseManager manager;
private ListView listView;
private SimpleCursorAdapter adapter;
final String[] from=new String[] {UserDatabase.NAME,UserDatabase.NUMBER};
final int[] to=new int[] {R.id.nameDisplay,R.id.phoneDisplay};
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_details);
manager = new DatabaseManager(getApplicationContext());
manager.open();
Cursor cursor=manager.fetch();
listView = (ListView) findViewById(R.id.listViewId);
listView.setEmptyView(findViewById(R.id.empty));
adapter = new SimpleCursorAdapter(getApplicationContext(),
R.layout.row_item, cursor, from, to, 0);
adapter.notifyDataSetChanged();
listView.setAdapter(adapter);
FloatingActionButton fab = (FloatingActionButton) findViewById(R.id.fab);
fab.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
final AlertDialog.Builder dialogBuilder = new AlertDialog.Builder(DetailsActivity.this);
LayoutInflater inflater = DetailsActivity.this.getLayoutInflater();
final View dialogView = inflater.inflate(R.layout.custom_dialog, null);
dialogBuilder.setView(dialogView);
final EditText name = (EditText) dialogView.findViewById(R.id.dialogEditNmID);
final EditText phone = (EditText) dialogView.findViewById(R.id.dialogEditPhID);
dialogBuilder.setTitle("Add Details");
dialogBuilder.setPositiveButton("Add", new DialogInterface.OnClickListener() {
#Override
public void onClick(DialogInterface dialog, int which) {
if (!TextUtils.isEmpty(name.getText().toString()) &&
!TextUtils.isEmpty(phone.getText().toString())) {
/*adapter.notifyDataSetChanged();
manager.insert(name.getText().toString(), phone.getText().toString());
Toast.makeText(getApplicationContext(),
"Added " + name.getText().toString(), Toast.LENGTH_SHORT).show();*/
insertData(name.getText().toString(),phone.getText().toString());
} else {
Toast.makeText(getApplicationContext(),
"Empty field(s)", Toast.LENGTH_SHORT).show();
}
}
});
dialogBuilder.setNegativeButton("Cancel", new DialogInterface.OnClickListener() {
#Override
public void onClick(DialogInterface dialog, int which) {
dialog.dismiss();
}
});
AlertDialog b = dialogBuilder.create();
b.show();
// listView.setAdapter(adapter);
//adapter.notifyDataSetChanged();
}
});
}
public void insertData(String fname,String phnumber){
manager.insert(fname,phnumber);
listView.setAdapter(adapter);
adapter.notifyDataSetChanged();
}
}
Some of the statements are commented because I tried to get the desired result but couldn't get it.

There's a couple things here you have to change. Taking a look at this code:
dialogBuilder.setPositiveButton("Add", new DialogInterface.OnClickListener() {
#Override
public void onClick(DialogInterface dialog, int which) {
if (!TextUtils.isEmpty(name.getText().toString()) && !TextUtils.isEmpty(phone.getText().toString())) {
adapter.notifyDataSetChanged();
manager.insert(name.getText().toString(), phone.getText().toString());
Toast.makeText(getApplicationContext(), "Added " + name.getText().toString(), Toast.LENGTH_SHORT).show();
} else {
Toast.makeText(getApplicationContext(), "Empty field(s)", Toast.LENGTH_SHORT).show();
}
}
});
When you click the "Add" button, right away you call adapter.notifyDataSetChanged();. In your case, you are only supposed to call that after you have added items to listView, but you haven't added anything yet.
You insert into your database using manager.insert(name.getText().toString(), phone.getText().toString());, but you don't update listView with your newly added data. You need to insert that data to the database, and then also add that data to listView.
Now you can call adapter.notifyDataSetChanged();.
I would recommend that when you want to insert into your database, create a method which will insert the data, add the new data to the listView, and then tell the adapter to refresh.
Edit
Regarding your recent edit, there's still a few things that need to be taken care of.
You should not have listView.setAdapter(adapter) in the method. You had it right the first time (in onCreate() but before the dialog builder).
You call manager.insert(fname,phnumber);, but still do not add the newly inserted data to listView.
Here's pseudocode for what you should have in your method:
public void insertData(String fname,String phnumber){
manager.insert(fname,phnumber);
// Code to add the data you just inserted into the manager above to `listView`.
adapter.notifyDataSetChanged();
}
Remember, adapter.notifyDataSetChanged(); only updates listView if there's changes to listView, and as of right now you haven't added/deleted/modified listView.

After you insert the entries in your database, you should fetch the data again so that your list has the newest entry. So you can either modify your code to be able to add a data point to the list you are passing to the adapter or refetch the data from the database after insertions and before notifyDatasetChanged().

i have did some changes into the code please try it and let me know if it is helpful or not
public class DetailsActivity extends AppCompatActivity {
private DatabaseManager manager;
private ListView listView;
private SimpleCursorAdapter adapter;
final String[] from=new String[] {UserDatabase.NAME,UserDatabase.NUMBER};
final int[] to=new int[] {R.id.nameDisplay,R.id.phoneDisplay};
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_details);
manager = new DatabaseManager(getApplicationContext());
manager.open();
listView = (ListView) findViewById(R.id.listViewId);
listView.setEmptyView(findViewById(R.id.empty));
adapter = new SimpleCursorAdapter(getApplicationContext(),R.layout.row_item, cursor, from, to, 0);
//adapter.notifyDataSetChanged();
FloatingActionButton fab = (FloatingActionButton) findViewById(R.id.fab);
fab.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
final AlertDialog.Builder dialogBuilder = new AlertDialog.Builder(DetailsActivity.this);
LayoutInflater inflater = DetailsActivity.this.getLayoutInflater();
final View dialogView = inflater.inflate(R.layout.custom_dialog, null);
dialogBuilder.setView(dialogView);
final EditText name = (EditText) dialogView.findViewById(R.id.dialogEditNmID);
final EditText phone = (EditText) dialogView.findViewById(R.id.dialogEditPhID);
dialogBuilder.setTitle("Add Details");
dialogBuilder.setPositiveButton("Add", new DialogInterface.OnClickListener() {
#Override
public void onClick(DialogInterface dialog, int which) {
if (!TextUtils.isEmpty(name.getText().toString()) &&
!TextUtils.isEmpty(phone.getText().toString())) {
adapter.notifyDataSetChanged();
manager.insert(name.getText().toString(), phone.getText().toString());
Toast.makeText(getApplicationContext(),
"Added " + name.getText().toString(), Toast.LENGTH_SHORT).show();
Cursor cursor = manager.fetch();
listView.setAdapter(adapter);
} else {
Toast.makeText(getApplicationContext(),
"Empty field(s)", Toast.LENGTH_SHORT).show();
}
}
});
dialogBuilder.setNegativeButton("Cancel", new DialogInterface.OnClickListener() {
#Override
public void onClick(DialogInterface dialog, int which) {
dialog.dismiss();
}
});
AlertDialog b = dialogBuilder.create();
b.show();
// listView.setAdapter(adapter);
//adapter.notifyDataSetChanged();
}
});
}}

Try to use notifyDataSetChanged after insert operation. In all place where you call(try to call) notify manager data isn't change yet.

Updating cursor after returning from intent to mainactivity

So i am having this listview in my MainActivity, which is updated every time the main activity is started or resumed.
The code for that is
#Override
public void onResume()
{
super.onResume();
Cursor array_list_patients = mydb.getAllPatientsDetails();
PatientAdapter arrayAdapter = new n
PatientAdapter(this,array_list_patients);
obj = (ListView)findViewById(R.id.listView1);
obj.setAdapter(arrayAdapter);
}
Now for the listview in the MainActivity i have a setOnItemClickListener as shown below, which basically displays the data in another activity "ModifyPatient". Code for that is:
Cursor array_list_patients = mydb.getAllPatientsDetails();
final PatientAdapter arrayAdapter = new PatientAdapter(this,array_list_patients);
obj = (ListView)findViewById(R.id.listView1);
obj.setAdapter(arrayAdapter);
obj.setOnItemClickListener(new AdapterView.OnItemClickListener(){
#Override
public void onItemClick(AdapterView<?> arg0, View arg1, int arg2,long arg3) {
Cursor cur = (Cursor) arrayAdapter.getItem(arg2);
cur.moveToPosition(arg2);
int id_To_Search = cur.getInt(cur.getColumnIndexOrThrow("id"));
Bundle dataBundle = new Bundle();
dataBundle.putInt("id", id_To_Search);
Intent intent = new Intent(getApplicationContext(),ModifyPatient.class);
intent.putExtras(dataBundle);
startActivity(intent);
}
});
Now in the ModifyPatient class.. i can do Upate/Delete operations on the database entry. Now the problem is, when i do a delete operation and return back to the MainActivity, and click on any item in the listview, i get an OutOfBounds exception for the cursor. The current code for delete button in the ModifyPatient class is as follows:
deleteButton.setOnClickListener(new View.OnClickListener() {
public void onClick(View view) {
AlertDialog.Builder builder = new AlertDialog.Builder(ModifyPatient.this);
builder.setMessage(R.string.deleteContact)
.setPositiveButton(R.string.yes, new DialogInterface.OnClickListener() {
public void onClick(DialogInterface dialog, int id) {
mydb.deletePatient(id_To_Update);
Toast.makeText(getApplicationContext(), "Deleted Successfully",
Toast.LENGTH_SHORT).show();
ModifyPatient.this.finish();
}
})
.setNegativeButton(R.string.no, new DialogInterface.OnClickListener() {
public void onClick(DialogInterface dialog, int id) {
// User cancelled the dialog
}
});
AlertDialog d = builder.create();
d.setTitle("Are you sure");
d.show();
}
});
This deletes the entry and returns to the mainactivity, but clicking on any of the items in the listview throws the error which i mentioned before.
I have done a small workaround, where i have replaced the below line:
ModifyPatient.this.finish();
with
Intent intent = new Intent(getApplicationContext(),MainActivity.class);
startActivity(intent);
But the problem with this is, the original activity remains in the background and a new MainActivity is forked. So pressing the back button, goes back to the original activity with the stale listview.
If somebody can help me out, with how to update the cursor, because i could not implement the swapcursor in my case. I am not sure what i am doing wrong.
Thank you in advance.

i set my variable "arrayAdapter" present in the onResume and onItemClickListener in the MainActivity from local to global, and that did the trick.
New code, where arrayAdapter is global:
public void onResume()
{
super.onResume();
Cursor array_list_patients = mydb.getAllPatientsDetails();
arrayAdapter = new PatientAdapter(this,array_list_patients);
obj = (ListView)findViewById(R.id.listView1);
obj.setAdapter(arrayAdapter);
}
and
arrayAdapter = new PatientAdapter(this,array_list_patients);
obj = (ListView)findViewById(R.id.listView1);
obj.setAdapter(arrayAdapter);
obj.setOnItemClickListener(new AdapterView.OnItemClickListener(){
#Override
public void onItemClick(AdapterView<?> arg0, View arg1, int arg2,long arg3) {
Cursor cur = (Cursor) arrayAdapter.getItem(arg2);
cur.moveToPosition(arg2);
int id_To_Search = cur.getInt(cur.getColumnIndexOrThrow("id"));
Bundle dataBundle = new Bundle();
dataBundle.putInt("id", id_To_Search);
Intent intent = new Intent(getApplicationContext(),ModifyPatient.class);
intent.putExtras(dataBundle);
startActivity(intent);
arrayAdapter.notifyDataSetChanged();
}
});

Add a Multiple-Delete option in ListView Android

In my app, information like file names are stored in the externally storage. They are then implemented into the app with the help of ListView. I can delete files individually with OnItemLongClickListener() but I want to select multiple files in ListView and then click a Delete button. How can I do this? My MainActivity file is below:
public class MainActivity extends AppCompatActivity {
ArrayList<FileName> filenames;
ListViewAdapter adapter;
ListView lv_filenames;
public Handler handler;
private String _path = Environment.getExternalStorageDirectory() + "/sample_directory/";
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
final EditorManager manager = new EditorManager(getApplicationContext());
manager.CreateNewDirectory();
lv_filenames = (ListView) findViewById(R.id.list);
handler = new Handler();
final Runnable r = new Runnable() {
public void run() {
filenames = manager.GetList();
adapter = new ListViewAdapter(getApplicationContext(), R.layout.listView, filenames);
lv_filenames.setAdapter(adapter);
lv_filenames.setOnItemLongClickListener(new AdapterView.OnItemLongClickListener() {
#Override
public boolean onItemLongClick(AdapterView<?> adapterView, View view, int file_name, long l) {
final File deleteFile = new File(_path + filenames.get(file_name).getName());
final String tempFileName = filenames.get(file_name).getName() + " is deleted";
AlertDialog.Builder builder = new AlertDialog.Builder(MainActivity.this);
builder.setTitle("Delete File");
builder.setMessage("Do you really want to delete this file?");
builder.setPositiveButton("Yes", new DialogInterface.OnClickListener() {
#Override
public void onClick(DialogInterface dialogInterface, int i) {
boolean deleted = deleteFile.delete();
if (deleted) {
Toast.makeText(getApplicationContext(), tempFileName, Toast.LENGTH_SHORT).show();
}
}
});
builder.setNegativeButton("No", new DialogInterface.OnClickListener() {
#Override
public void onClick(DialogInterface dialogInterface, int i) {
// Do nothing.
}
});
builder.create();
AlertDialog dialog = builder.create();
dialog.show();
return false;
}
});
}
}
I deleted the extra code. Thanx for helping!
PS -
I heard that in Android 4.4 + files can't be deleted like this. What should I do?
EDIT -
I have seen those answers. But I want to create a button on whose click the check/uncheck buttons would be available. How can I do that? I want the Check/Uncheck buttons to be visible only when I click delete button. Also the other answers are a bit confusing.

I would have a button with a edit or delete icon and have it change the ListView to one with checkboxes in each view. Either make a new ListView with a new Adapter or just tell adapter and set a boolean in it, and then dataSetChange the Adapter.

I fixed my problem. I use a SparseBooleanAdapter to register the delete options.Then I press delete button to delete them.

listview does not get updated android

I am very new to Android and am trying to create an app for travel help. It has a couple of components including -> enabling the user to customize a checklist. Apart from the default list, items can be added and deleted.
For adding,
I'm using a dynamic layout through the class file with no XML. It works perfectly :)
For deleting an item from the list,
I created an adpater, a listview and am trying to delete the selected item. With the help of a couple of "toasts", I am able to derive that, an item is being deleted from the list, but the view is not getting updated.
I have checked and tried numerous solutions, but none of them seem to be working. I am attching my java file, in which the display and customization of the list takes place.
The code seems a little long, but its fairly easy to understand. Any help would be greatly appreciated! :)
public class Dynamic extends ListActivity{
public String[] A = new String[100];
public String[] B = new String[100];
public int j=0, m=0, b=0, tot1=0, tot2=0;
public int a[]=new int[100];
CheckBox c, cc;
ArrayList<String> list2 = new ArrayList<String>();
ArrayList<String> list4 = new ArrayList<String>();
ArrayAdapter<String> adapter;
ArrayAdapter<String> adapter2;
private SparseBooleanArray sba;
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
ScrollView sv = new ScrollView(this);
final LinearLayout ll = new LinearLayout(this);
ll.setOrientation(LinearLayout.VERTICAL);
sv.addView(ll);
final ListView list3=new ListView(this);
list3.setId(android.R.id.list);
list3.setChoiceMode(list3.CHOICE_MODE_MULTIPLE);
ll.addView(list3);
adapter = new ArrayAdapter<String>(this, android.R.layout.simple_list_item_multiple_choice, list2);
Bundle extras = getIntent().getExtras();
if (extras != null) {
A = extras.getStringArray("var");
int i = extras.getInt("var2");
B = extras.getStringArray("var3");
int k = extras.getInt("var4");
for (j=0;j<i;j++)
{
cc = new CheckBox(this);
cc.setText(A[j]);
ll.addView(cc);
list2.add(A[j]);
adapter.notifyDataSetChanged();
}
for (m=0;m<k;m++)
{
cc = new CheckBox(this);
cc.setText(B[m]);
ll.addView(cc);
list2.add(B[m]);
adapter.notifyDataSetChanged();
}
}
Button b = new Button(this);
b.setText("Delete Item");
ll.addView(b);
b.setOnClickListener(new View.OnClickListener()
{
#Override
public void onClick(View v)
{
AlertDialog.Builder alertDialog = new AlertDialog.Builder(Dynamic.this);
alertDialog.setTitle("Confirm Delete...");
alertDialog.setMessage("Are you sure you want to delete the selected item from the list?");
alertDialog.setPositiveButton("YES", new DialogInterface.OnClickListener()
{
public void onClick(DialogInterface dialog,int which)
{
sba=new SparseBooleanArray();
sba.clear();
sba=list3.getCheckedItemPositions();
ListView lv = getListView();
Toast.makeText(getApplicationContext(), "checked " + sba, Toast.LENGTH_SHORT).show();
int itemCount = getListView().getCount();
Toast.makeText(getApplicationContext(), "calc done " + itemCount, Toast.LENGTH_SHORT).show();
for(int i=itemCount-1; i >= 0; i--){
Toast.makeText(getApplicationContext(), "in the loop " + i, Toast.LENGTH_SHORT).show();
Toast.makeText(getApplicationContext(), " " + sba.get(i), Toast.LENGTH_SHORT).show();
list2.add((list2.get(i)));
Toast.makeText(getApplicationContext(), " " + list2.get(i), Toast.LENGTH_SHORT).show();
adapter.remove(list2.get(i));
list3.invalidate();
adapter.notifyDataSetChanged();
list3.setAdapter(adapter);
Toast.makeText(getApplicationContext(), " " + list2, Toast.LENGTH_SHORT).show();
}
sba.clear();
}
});
alertDialog.setNegativeButton("NO", new DialogInterface.OnClickListener(){
public void onClick(DialogInterface dialog, int which){
Toast.makeText(getApplicationContext(), "The item has NOT been deleted!", Toast.LENGTH_SHORT).show();
dialog.cancel();
}
});
alertDialog.show();
setListAdapter(adapter);
}
});
this.setContentView(sv);
}
}

in order to update your listView try this in your adampter
notifyDataSetChanged();
But You should run it on the UI thread. Create an handler within the UI thread and then post Runable to it
like this
private class Asyn_SaveData extends AsyncTask<Void, Void, Void> {
#Override
protected Void doInBackground(Void... params) {
//Do something here that will run in backGround
}
#Override
protected void onPostExecute(Void result) {
// TODO Auto-generated method stub
super.onPostExecute(result);
//and this function is called automatically by doInBackground
// after it finish its work
//in your example refresh your ListView
notifyDataSetChanged();
}
}
and to use the AsyncTask
new Asyn_SaveData().execute(null,null,null);
Just remembre AsyncTask must be subClassed
or
myListView.invalidateViews();

Have a Search Activity return a result?

Hi I was wondering how I can get my Search Activity to return a result back to the Activity that started it.
I currently have a Search Dialog implemented (meaning the search Activity starts once the Search button on the phone is clicked).
Here is my code for the Search activity which is a list view.
public class ItemFinder extends ListActivity {
public static final int REQUEST_CODE = 1; // get it?
Vector<String> upcCodes;
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.search);
upcCodes = new Vector<String>();
ListView lv = (ListView) findViewById(android.R.id.list);
lv.setOnItemClickListener(new OnItemClickListener(){
#Override
public void onItemClick(AdapterView<?> a, View v, int position,
long id) {
String upc = upcCodes.elementAt(position);
setResult(RESULT_OK);
}
});
// Get the intent, verify the action and get the query
Intent intent = getIntent();
if (Intent.ACTION_SEARCH.equals(intent.getAction())) {
String query = intent.getStringExtra(SearchManager.QUERY);
ProgressDialog dialog = ProgressDialog.show(ItemFinder.this, "Searching",
"Searching. Please wait...", true);
performSearch(query);
dialog.hide();
dialog.dismiss();
}
}
public void performSearch(String query){
String result = new SmartShopClient().SearchItems(query);
List<String> dataList = new ArrayList<String>();
String _parsedResult[] = result.split("\\n");
for( int i = 0; i<_parsedResult.length; i++){
String _splitData[] = _parsedResult[i].split("\\|");
String itemName = _splitData[0];
String itemUPC = _splitData[1];
dataList.add(itemName);
upcCodes.add(itemUPC);
}
ArrayAdapter<String> arr = new ArrayAdapter<String>(this, android.R.layout.simple_list_item_1, dataList);
this.setListAdapter(arr);
}
}
So the search is working all fine and dandy, but I want it so when I click one of the results in the ListView, for it to return data back to the main activity with some data, say the name of the clicked searched result.
Thanks.

What you want to do is launch the search using startActivityForResult. See an explanation here.
This way, you can pass your search results back to the activity which launched it.

That would happen in your setOnItemClickListener method, where you could launch an explicit intent naming the desired activity with extra data.
Edit : I'm not quite sure of how startActivityForResult() would be implemented since we're talking about the search activity of the application, meaning it's launched by the Android search specific module ; that's why i suggested the above solution.

I ended up doing this:
public boolean onSearchRequested() {
askSearchQuery();
return true;
}
public void sendSearchRequest(String query){
Intent mIntent = new Intent(this, ItemFinder.class);
mIntent.setAction(Intent.ACTION_SEARCH);
mIntent.putExtra(SearchManager.QUERY, query);
startActivityForResult(mIntent, ItemFinder.REQUEST_CODE);
}
public void askSearchQuery() {
final EditText input = new EditText(SmartShop.this);
AlertDialog.Builder adb = new AlertDialog.Builder(SmartShop.this);
adb.setTitle("Search Items");
adb.setMessage("Please input the name of the item you are looking for.");
adb.setView(input);
adb.setPositiveButton("Ok", new DialogInterface.OnClickListener() {
public void onClick(DialogInterface dialog, int whichButton) {
Editable upc = input.getText();
sendSearchRequest(upc.toString());
dialog.cancel();
}
});
adb.setNegativeButton("Cancel", new DialogInterface.OnClickListener() {
public void onClick(DialogInterface dialog, int whichButton) {
dialog.cancel();
}
});
adb.create().show();
}
And then I hooked the
protected void onActivityResult (int requestCode, int resultCode, Intent data) {