Develop Reference

How can i refresh my ListView for manipulation of data ? like - Insert, Update & Delete

I am trying to refresh my listview for every insert, update, delete data from/into sqlite database.But, it can not work. I already used finishActivityFromChild(getParent(),1); but sometimes my app can not open.
How can i use notifyDataSetChanged(); for this code or any way ?
public class MainActivity extends AppCompatActivity {
DbHelper myDB;
Button btn_feedback;
FloatingActionButton btn_fab;
private String selectedName;
private int selectedID;
private boolean isUserClickedBackButton = false;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
myDB = new DbHelper(this);
final ListView listView = (ListView)findViewById(R.id.listview_main);
registerForContextMenu(listView);
Intent receivedIntent = getIntent();
selectedID = receivedIntent.getIntExtra("id",-1);
selectedName = receivedIntent.getStringExtra("item");
final ArrayList<String> theList = new ArrayList<>();
Cursor data = myDB.getListContents();
if (data.getCount() == 0){
Toast.makeText(getApplicationContext(),"Data Empty !",Toast.LENGTH_SHORT).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 l) {
String item1 = parent.getItemAtPosition(position).toString();
Toast.makeText(getApplicationContext(),"You Select - " + theList.get(position),Toast.LENGTH_SHORT).show();
Cursor data = myDB.getItemID(item1);
int itemID = -1;
while(data.moveToNext()){
itemID = data.getInt(0);
}
if(itemID > -1){
Intent editScreenIntent = new Intent(getApplicationContext(), Edit_Main.class);
editScreenIntent.putExtra("id",itemID);
editScreenIntent.putExtra("ITEM1",item1);
startActivity(editScreenIntent);
}
else{
Toast.makeText(getApplicationContext(),"No ID Associated With That Name !",Toast.LENGTH_SHORT);
}
}
});
}
}
btn_fab = (FloatingActionButton)findViewById(R.id.fab);
btn_fab.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
startActivity(new Intent(getApplicationContext(), Create_Main.class));
}
});
}}

Just Clear your arrayList inside while loop as below :
while (data.moveToNext()){
//////////////////////////////////////////////////
if(theList!=null && theList.size()>0){
theList.clear();
}
/////////////////////////////////////
theList.add(data.getString(1));
.....
.....
}
Hope, it helps.

Line by line output in the ListView with ArrayAdapter

I have an adapter, which get second parameter from "while" loop, so it must show me a query result in the ListView but it only shows me the last meaning of variable "string_word" instead. But even log.d output what I want line by line. Here is the code :
public class MainActivity extends Activity implements OnClickListener {
final String LOG_TAG = "myLogs";
IdDB idh;
SynDB sqh;
SQLiteDatabase sqdb, iddb;
Button btnOk;
EditText etWord;
String eWord;
ListView lvMain;
public ArrayAdapter<String> adapter;
public String string_word;
public String[] syns;
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
etWord = (EditText) findViewById(R.id.etWord);
btnOk = (Button) this.findViewById(R.id.btnOk);
lvMain = (ListView) findViewById(R.id.lvMain);
btnOk.setOnClickListener(btnOkListener);
//initialize our class-cover IdDB
idh = new IdDB(this);
// initialize our class-cover SynDB
sqh = new SynDB(this);
// we need db to read and write
sqdb = sqh.getWritableDatabase();
iddb = idh.getWritableDatabase();
}
public void displayListView(){
// создаем адаптер
adapter = new ArrayAdapter<String>(this,
android.R.layout.simple_list_item_1, syns);
}
public OnClickListener btnOkListener = new OnClickListener(){
#Override
public void onClick(View v) {
eWord = etWord.getText().toString();
switch (v.getId()){
case R.id.btnOk:
String query = //long SQL query (return "word")
Log.d(LOG_TAG, query);
Log.d(LOG_TAG, "--- Rows in mytable: ---");
// query to get Cursor
Cursor cursor = sqdb.rawQuery(query, null);
int wordColIndex = cursor.getColumnIndex(SynDB.Word);
while (cursor.moveToNext()) {
string_word = cursor.getString(wordColIndex);
Log.d(LOG_TAG, "word = "+ string_word);
syns = new String[] {string_word};
displayListView();
// присваиваем адаптер списку
lvMain.setAdapter(adapter);
}
cursor.close();
break;
default:
break;
} // close switch
} // close onClick
};
protected void onStop() {
super.onStop();
sqdb.close();
sqh.close();
}
public boolean onCreateOptionsMenu(Menu menu) {
getMenuInflater().inflate(R.menu.main, menu);
return true;
}
#Override
public void onClick(View view) {
}
}

What it does:
Create an array with one item string_word calls displayListView and set another adapter to the ListView
And do it everytime i gets a value from the list.
To do what you want, you should change your logic a bit.
You will create the adapter only one time.
You will add every string to a List (more flexible than an array since here you don't know how many words you will have)
So:
Delete all displayListView method calls and add one in the onCreate. (and every lvMain.setAdapter(adapter);)
Your displayListView should be the only one which sets the adapter to the ListView
public void displayListView(){
// создаем адаптер
adapter = new ArrayAdapter<String>(this,
android.R.layout.simple_list_item_1, syns);
lvMain.setAdapter(adapter);
}
Something like:
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
etWord = (EditText) findViewById(R.id.etWord);
btnOk = (Button) this.findViewById(R.id.btnOk);
lvMain = (ListView) findViewById(R.id.lvMain);
btnOk.setOnClickListener(btnOkListener);
//initialize our class-cover IdDB
idh = new IdDB(this);
// initialize our class-cover SynDB
sqh = new SynDB(this);
// we need db to read and write
sqdb = sqh.getWritableDatabase();
iddb = idh.getWritableDatabase();
displayListView();
}
Go in the top where is
public String[] syns;
and change it type to List<String> (ArrayAdapter have a constructor with List, so don't worry.)
public List<String> syns;
Here your
int wordColIndex = cursor.getColumnIndex(SynDB.Word);
while (cursor.moveToNext()) {
string_word = cursor.getString(wordColIndex);
Log.d(LOG_TAG, "word = "+ string_word);
syns = new String[] {string_word};
displayListView();
// присваиваем адаптер списку
lvMain.setAdapter(adapter);
}
should look like
int wordColIndex = cursor.getColumnIndex(SynDB.Word);
while (cursor.moveToNext()) {
string_word = cursor.getString(wordColIndex);
Log.d(LOG_TAG, "word = "+ string_word);
syns = new String[] {string_word};
}
Now you should add to the List every word the Cursor return, so you should use .add method.
int wordColIndex = cursor.getColumnIndex(SynDB.Word);
while (cursor.moveToNext()) {
string_word = cursor.getString(wordColIndex);
Log.d(LOG_TAG, "word = "+ string_word);
syns.add(string_word);
}
When ready, call adapter.notifyDataSetChanged() to notify to the Adapter that you finished to change your data and can redraw the items in the ListView

Android Spinner Error

hello I try to put in my java Code a Spinner, but it shows in the else if statement error:
private EditText textName;
private EditText textContent;
private Spinner CategorySpinner;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_text);
configureButton1();
configureButton2();
textName = (EditText) findViewById(R.id.editTextName);
textContent = (EditText) findViewById(R.id.editContent);
CategorySpinner = (Spinner) findViewById(R.id.editCategorySpinner);
}
private void configureButton1() {
Button del = (Button)findViewById(R.id.btNewText);
del.setOnClickListener(new OnClickListener() {
#Override
public void onClick(View v) {
Intent myIntent = new Intent(v.getContext(), StartActivity.class);
v.getContext().startActivity(myIntent);
}
});
}
private void configureButton2() {
Button save = (Button) findViewById(R.id.btSave);
save.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
if (textName.getText().length() == 0) {
textName.requestFocus();
return;
} else if (textContent.getText().length() == 0) {
textContent.requestFocus();
return;
} else if (CategorySpinner.**getText**().length() == 0) {
CategorySpinner.requestFocus();
return;
} else {
//next Step: get the mood
Intent myIntent = new Intent(v.getContext(), Activity2.class);
myIntent.putExtra("textName", textName.getText().toString());
myIntent.putExtra("textContent", textContent.getText().toString());
myIntent.putExtra("CategorySpinner", CategorySpinner.**getText()**.toString());
v.getContext().startActivity(myIntent);
}
}
}
});
}
it shows in the CategorySpinner.getText() an error. I hope you can help me.
I´ve tried a lot, but not found a solution.

private void initSpinnerList() {
spinner = (Spinner) findViewById(R.id.spinner);
spinner.setOnItemSelectedListener(listner);
categories = new ArrayList<String>();
categories.add("S");
categories.add("T");
categories.add("U");
categories.add("V");
categories.add("W");
categories.add("X");
categories.add("Y");
categories.add("Z");
ArrayAdapter<String> dataAdapter = new ArrayAdapter<String>(this,
android.R.layout.simple_spinner_item, categories);
dataAdapter
.setDropDownViewResource(android.R.layout.simple_spinner_dropdown_item);
spinner.setAdapter(dataAdapter);
}
private OnItemSelectedListener listner = new OnItemSelectedListener() {
/*
* (non-Javadoc)
*
* #see
* android.widget.AdapterView.OnItemSelectedListener#onItemSelected(
* android .widget.AdapterView, android.view.View, int, long)
*/
#Override
public void onItemSelected(AdapterView<?> parent, View view,
int position, long id) {
String item = parent.getItemAtPosition(position).toString();
/// on item selected data
}
/*
* (non-Javadoc)
*
* #see
* android.widget.AdapterView.OnItemSelectedListener#onNothingSelected
* (android .widget.AdapterView)
*/
#Override
public void onNothingSelected(AdapterView<?> parent) {
}
};
#Override
public void onClick(View v) {
if (spinner != null && categories != null) {
Log.v("Selected Spinner Item ",
categories.get(spinner.getSelectedItemPosition()));
}
}

You haven't provided adapter to spinner. please use below code for adapter:
Spinner spinner = new Spinner(this);
ArrayAdapter<String> spinnerArrayAdapter = new ArrayAdapter<String>(this, android.R.layout.simple_spinner_dropdown_item, spinnerArray);
spinner.setAdapter(spinnerArrayAdapter);
after that if u want text of an item than use below code:
String value = spinnerArray[spinner.getSelectedItemPosition()];
which will return value of selected item in spinner. Default it is 0.

How to reload a spinner in Android?

Can anybody tell me the code to reload a Spinner?
I have created a small app where I can add some items and delete unwanted items. The items added will be showed in a spinner. Once I select an item from the spinner and delete it clicking the Delete Button, The item is getting deleted from the database & I get a Toast displayed "Item Deleted". But its still showing in the spinner until I logout and logs in once again. Here, I think I need to reload the spinner once again on the Delete button click. Can anybody help me out to do that?
public class DeleteChildActivity extends Activity {
TextView name;
Button delete;
Spinner spinner2;
private String URL = "/ParentProfileServlet";
private String URL1 = "/ChildProfileServlet";
private String URL2 = "/DeleteChildServlet";
ArrayList<NameValuePair> postparameter;
public static int selectChildId;
public static String imei;
ParentDetailsMod parentModel;
private ArrayList<ChildDetails> childArray = null;
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.delete_child);
delete = (Button) findViewById(R.id.B_delchild);
spinner2 = (Spinner) findViewById(R.id.childspinner);
childArray = new SelectParser().parseSelectXml(response);
ArrayList<String> stringArray = new ArrayList<String>();
for (ChildDetails childModel : childArray) {
String str;
str = childModel.getName();
stringArray.add(str);
}
// spinner = (Spinner) findViewById(R.id.spinner11);
ArrayAdapter<String> adapter = new ArrayAdapter<String>(
getApplicationContext(), android.R.layout.simple_list_item_1,
stringArray);
adapter.setDropDownViewResource(android.R.layout.simple_spinner_dropdown_item);
spinner2.setAdapter(adapter);
spinner2.setPrompt(getString(R.string.selectLabel));
spinner2.setOnItemSelectedListener(new AdapterView.OnItemSelectedListener() {
#Override
public void onItemSelected(AdapterView<?> arg0, View arg1,
int position, long arg3) {
imei = childArray.get(position).getImei_num();
selectChildId = childArray.get(position).getChild_id();
}
#Override
public void onNothingSelected(AdapterView<?> arg0) {
// TODO Auto-generated method stub
}
});
delete.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
// spinner.performClick();
// String id = spinner2.getSelectedItem().toString();
// selectChildId = id.substring(0, id.indexOf("--"));
postparameter = new ArrayList<NameValuePair>();
String parent_id = LoginPageActivity.id;
postparameter
.add(new BasicNameValuePair("parent_id", parent_id));
postparameter.add(new BasicNameValuePair("child_id",
selectChildId + ""));
String response = null;
try {
response = CustomHttpClient.executeHttpPost(URL2,
postparameter);
System.out.println("response:" + response);
if (response.trim().compareTo("success") == 0) {
Toast.makeText(getApplicationContext(),
"Child deleted", Toast.LENGTH_LONG).show();
} else {
Toast.makeText(getApplicationContext(),
"Failed to delete", Toast.LENGTH_LONG).show();
}
} catch (Exception e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
});

You can use notifyDataSetChanged(); method to reload the adapter or display the changed data.

You should delete the item from you adapter list and then call spinner.notifyDataSetChanged() method to refresh you spinner

the App. Crashs when delete item from ListView

I have an SQLite table and in the certain activity I obtain all the names fom the table and populate a listview with these names.
Inside the listview listener, the user have can delete the selected item.
The problem is when I delete the item the app crashes.
Please take a look on my code:
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.mylocations);
tv_counter = (TextView) findViewById(R.id.counter);
tv_testCounter = (TextView) findViewById(R.id.testCounter);
lv = (ListView) findViewById(R.id.mylist);
mpoh = new MP_DB(this);
db = mpoh.getWritableDatabase();
cv = new ContentValues();
if (hasRecords()) {
Toast.makeText(getBaseContext(), getRowsNum()+" row(s)", Toast.LENGTH_SHORT).show();
get_MPNames();
arrayToArrayList();
setListView();
lv.setOnItemClickListener(listViewListener);
} else {
Toast.makeText(getBaseContext(), "NO RECORDS"+","+getRowsNum()+"rows", Toast.LENGTH_SHORT).show();
}
}
Here are the method to convert the array to arraylist, and the listview listener:
private void arrayToArrayList() {
int s = str.length;
al = new ArrayList<String>();
for (int i=0; i < s; i++) {
al.add(str[i]);
}
}
private int getRowsNum() {
return mpoh.getCurrentRowNumber();
}
OnItemClickListener listViewListener = new OnItemClickListener() {
#Override
public void onItemClick(AdapterView<?> arg0, View arg1, int arg2,
long arg3) {
// TODO Auto-generated method stub
pos = arg2;
showDialoge();
}
};
Here how I delete element from the DB and the ListView:
private void deleteMPfromListView(int pos) {
al.remove(pos);
adapter.notifyDataSetChanged();
Toast.makeText(getBaseContext(), al.size()+" rows left in list view", Toast.LENGTH_SHORT).show();
}
private void deleteMPFromDB(int pos) {
mpoh.deleteMP(pos);
Toast.makeText(getBaseContext(), getRowsNum()+" rows left in DB", Toast.LENGTH_SHORT).show();
}
private Boolean hasRecords() {
if (getRowsNum() == 0) {
return false;
} else {
return true;
}
}
private void setListView() {
adapter = new ArrayAdapter<String>(this, android.R.layout.simple_list_item_1,
android.R.id.text1, al);
lv.setAdapter(adapter);
}
private void get_MPNames() {
str = new String[getRowsNum()];
for (int i=0; i <= getRowsNum()-1; i++) {
str[i] = mpoh.getMP_Name(i+1);
} //tv_testCounter.setText(str[87]);
}

Removing from the database has nothing to do with removing them from the ListView. I have not code of your implementation but you may try something like this too dynamically add or remove items:
public class LVDemo extends ListActivity {
// handles the ListView data
ArrayAdapter<String> adapter;
// Items that are displayed
ArrayList<String> listItems=new ArrayList<String>();
#Override
public void onCreate(Bundle icicle) {
super.onCreate(icicle);
setContentView(R.layout.main);
adapter=new ArrayAdapter<String>(this, android.R.layout.simple_list_item_1,
listItems);
setListAdapter(adapter);
}
/**
* Remove item.
*/
public void removeItem(int index) {
listItems.remove(index);
adapter.notifyDataSetChanged();
}
}
In General: You change the the ArrayList containing the element and then notify the adapter for the ListView