I have a question regarding this simple frequently occurring situation in android .
I have an activity that will invoke the async task and async task will draw values from SQLite database and update on the UI. I used Async task to make the UI reponsive and fast.
This is the code I have been working on.
SqlHandler sqlHandler;
#BindView(R.id.list) ListView listView;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity1);
ButterKnife.bind(this);
sqlHandler = new SqlHandler(this);
new DisplayAll(this).execute();
listView.setOnItemClickListener((AdapterView<?> parent, View view,
int position, long id) -> {
Intent i = new Intent(getApplicationContext(), Activity2.class);
String text = textView.getText().toString();
startActivity(i);
});
}
private class DisplayAll extends AsyncTask<Void, Void, Void> {
int null_val;
final ArrayList<listRow=> myList = new ArrayList<>();
private WeakReference<Activity> mActivity;
public DisplayAll(Activity activity) {
mActivity = new WeakReference<>(activity);
}
#Override
protected Void doInBackground(Void... params) {
myList.clear();
String query = " ...";
Cursor c1 =sqlHandler.selectQuery(query);
if (c1 != null && c1.getCount() != 0) {
if (c1.moveToFirst()) {
do {
.....
} while (c1.moveToNext());
}
}
try {
null_val = Objects.requireNonNull(c1).getCount();
c1.close();
}
catch (NullPointerException e)
{
Log.e("NPE", "" + e);
}
return null;
}
#Override
protected void onPostExecute(Void param) {
// get a reference to the activity if it is still there
Activity activity = mActivity.get();
if (activity == null || activity.isFinishing()) return;
ProgressBar prgBar=findViewById(R.id.prgbar);
listAdapter Adapter;
prgBar.setVisibility(View.GONE);
Adapter = new listAdapter(getApplicationContext(), myList);
listView.setAdapter(Adapter);
}
}
I had checked this question also.I have added the weak reference to my class now. But still Android Studio warns me about the memory leak.
I tried to change it to static, but changing the sqlhandler as static also causes memory leak. To change the async task to a top-level class is not good for me. I have many async tasks in different activities.
So anyone have any idea how to tackle this?
Related
I have a ListView which I populate with data from DataStore or from my local database.
I am checking some condition that will determine whether I will fetch data from the DataStore or database. When I fetch from the database the ListView automatically refreshes itself, but when I fetch from the DataStore it does not. I then have to click my TextView, which is below ListView, and when I click it the soft keyboard appears and then my ListView is populated with data from DataStore.
My activity that has the ListView:
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_xyz);
list_View = (ListView) findViewById(R.id.data_listView);
list_View.setChoiceMode(ListView.CHOICE_MODE_MULTIPLE_MODAL);
list_View.setMultiChoiceModeListener(new Selector());
adapter = new MyAdapter(context,Long.valueOf(id),isOnline());
list_View.setAdapter(adapter);
list_View.setSelection(adapter.getCount() - 1);
adapter.registerDataSetObserver(new DataSetObserver() {
#Override
public void onChanged() {
super.onChanged();
list_View.setSelection(adapter.getCount() - 1);
}
LoadDataTask ldt = new LoadDataTask();
ldt.execute("123456789");
}
private void loadDataFromDataStore(final Long contactId){
final ArrayList<Data> data = new ArrayList<>();;
d("loadingdataFromDatasore");
GetDataTask task = new GetDataTask(new ApiTask.ResultListener() {
#Override
public void successHook(Object o) {
if (o instanceof GetDataResponse) {
GetDataResponse res = (GetDataResponse) o;
if (res.getData() != null && res.getData().getItems() != null) {
for (ListDataItem i : res.getData().getItems()) {
Data dp = new Data(i.getPosition(), i.getMessage(), i.getDateCreated(),i.getMessageId(),1);
adapter.addFromOtherThread(dp);
}
}
d("Messages loaded from server: " + adapter.getCount());
}
}
}
public class LoadDataTask extends AsyncTask<String,String,Void> {
#Override
protected Void doInBackground(String... params){
if(isOnline && isFirstTime){
loadDataFromDataStore(Long.valueOf(params[0]));
}else{
//load from database
}
return null;
}
#Override
protected void onPostExecute(Void v){
adapter.notifyDataSetChanged();
}
}
My adapter class that extends BaseAdapter (I have removed unnecessary code for this question):
public class DataAdapter extends BaseAdapter {
private ArrayList<Data>data_list;
public DataAdapter(){
data_list = new ArrayList<>();
}
public void addFromOtherThread(Data object) {
data_list.add(object);
}
What am I missing that is making listview not to automatically refresh itself even after calling notifyDatasetChanged()?
change :
#Override
protected void onPostExecute(Void v){
adapter.notifyDataSetChanged();
}
}
to:
#Override
protected void onPostExecute(Void v){
adapter.notifyDataSetChanged();
list_View.setAdapter(adapter);
}
}
Let me know if more clarification is required by commenting below.
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_xyz);
list_View = (ListView) findViewById(R.id.data_listView);
list_View.setChoiceMode(ListView.CHOICE_MODE_MULTIPLE_MODAL);
list_View.setMultiChoiceModeListener(new Selector());
adapter = new MyAdapter(context,Long.valueOf(id),isOnline());
list_View.setAdapter(adapter);
list_View.setSelection(adapter.getCount() - 1);
adapter.registerDataSetObserver(new DataSetObserver() {
#Override
public void onChanged() {
super.onChanged();
list_View.setSelection(adapter.getCount() - 1);
}
loadDataFromDataStore("123456789")
}
private void loadDataFromDataStore(final Long contactId){
final ArrayList<Data> data = new ArrayList<>();;
d("loadingdataFromDatasore");
new GetDataTask(new ApiTask.ResultListener() {
#Override
public void successHook(Object o) {
if (o instanceof GetDataResponse) {
GetDataResponse res = (GetDataResponse) o;
if (res.getData() != null && res.getData().getItems() != null) {
for (ListDataItem i : res.getData().getItems()) {
Data dp = new Data(i.getPosition(), i.getMessage(), i.getDateCreated(),i.getMessageId(),1);
adapter.addFromOtherThread(dp);
}
}
d("Messages loaded from server: " + adapter.getCount());
adapter.notifyDatasetChanges();
}
}
}.execute();
}
GetDataTask should work on background internally you don't need to starts a AsyncTask from here.
If you want to use AsyncTask then your AsyncTask should wait for the result from GetDataTask which it is not doing in your code implementation.
I don't know which kind of framework you are using to making api call but your implementation seems to look wrong.
I have write the code on assumption bases if your GetDataTask is a AsyncTask or some background processor it will work perfectly.
Here is the code:
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
overridePendingTransition(R.anim.fadein, R.anim.fadeout);
setContentView(R.layout.startpage);
rowItems = new ArrayList<RowItem>();
//... Filling this array.
}
Later, from another activity StartPage.rowItems.size() throw NullPointerException
It can be 0 (failed to retrieve data or I did .clear()), but how, the hell, it became null? I definitely never set it to null.
One more point - this array variable is public static and I use it from another activity. Can it be possible android unloads parent activity (what contains all global variables for the whole app)?
P.S. I cannot check it more thoroughly, because this error is not appears in my emulator/devices, but I got reported it on Google Play. So I can't check what was before and when the array became null...
Thank you
More exact code:
public class StartPage extends Activity implements View.OnTouchListener {
public static List<RowItem> rowItems;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
overridePendingTransition(R.anim.fadein, R.anim.fadeout);
setContentView(R.layout.startpage);
rowItems = new ArrayList<RowItem>();
pDialog = new ProgressDialog(this);
pDialog.setMessage("Loading data...");
pDialog.setCancelable(false);
pDialog.show();
gc=new GetData();gc.execute();
}
public class GetData extends AsyncTask<Void, Void, Void> {
#Override
protected void onPreExecute() {
super.onPreExecute();
rowItems.clear();
inProgress=true;
}
#Override
protected Void doInBackground(Void... arg0) {
ServiceHandler sh = new ServiceHandler();
String jsonStr = sh.makeServiceCall(url, ServiceHandler.GET);
if (jsonStr != null) {
try {
JSONObject jsonObj = new JSONObject(jsonStr);
items = jsonObj.getJSONArray(TAG_COINS);
for (int i = 0; i < itemss.length(); i++) {
JSONObject c = items.getJSONObject(i);
String id = c.getString(TAG_ID).toUpperCase();
String price = c.getString(TAG_PRICE);
String name = c.getString(TAG_NAME);
RowItem item = new RowItem(id, name, price);
rowItems.add(item);
}
} catch (JSONException e) {
e.printStackTrace();
}
} else {
Log.e("ServiceHandler", "Couldn't get any data from the url");
}
return null;
}
#Override
protected void onPostExecute(Void result) {
super.onPostExecute(result);
inProgress=false;
pDialog.dismiss();
}
}
Then call another activity:
public boolean onTouch(View view, MotionEvent event) {
switch (event.getAction() & MotionEvent.ACTION_MASK) {
case MotionEvent.ACTION_UP:
int x = (int) event.getX();
int y = (int) event.getY();
int w=view.getWidth()-20;
int h=view.getHeight()-20;
if (x<w*0.05 || x>w*0.95 || y<h*0.13 ) return false; // Misclicked
if (x<w*0.5 && y<h*0.38) {
Intent intent = new Intent(this, MainActivity.class);
startActivity(intent);
}
}
return true;
}
On another activity (MainActivity), try to refresh the listview with the data from main activity:
public class MainActivity extends ListActivity implements View.OnClickListener {
void refresh_list() {
if (StartPage.rowItems.size()>0) { <-- Here is NPE
ListAdapter adapter = new CustomListAdapter(MainActivity.this,R.layout.list_item,StartPage.rowItems);
setListAdapter(adapter);
((BaseAdapter) getListAdapter()).notifyDataSetChanged();
}
}
Google play report:
Caused by: java.lang.NullPointerException
at halfprice.coinmanager.MainActivity.refresh_list(MainActivity.java:116)
at halfprice.coinmanager.MainActivity.onCreate(MainActivity.java:105)
at android.app.Activity.performCreate(Activity.java)
at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java)
Hope this helps...
you are loading your data in static ArrayList and Acessing it to different activity. its not good practice to do.
Let me first tell your answer as you have created this object in Oncreate(). Its better you make create it Globally than this problem will not occure.
Example :
public class StartPage extends Activity implements View.OnTouchListener {
public static List<RowItem> rowItems = new ArrayList<RowItem>();
OnCreate(){
//and perform the action you want to do.
}
//Hope this will help you definately.
Now Another Method which is the good Practice in Programming language
Passing data object from one Activity to another is simple, If you want to pass Array object than the object should be serialized. Eg;
ArrayList rowItems = new ArrayList();
for Passing array object you have to use intent PutExtra, Eg:
Intent intent = new Intent(SplashScreen.this, MainActivity.class);
intent.putExtra("key",array); startActivity(intent);
//intent.putExtra("key",array); will show error if your Model class is not implements Serializable eg: public class Model implements Serializable{
String id;
String price;
String name;
//generate your getter setter and set data in to this.
}
//For getting data in to another class just use
ArrayList<Model> data = (ArrayList<Model>)getIntent().getSerializable("key");
Now you can play arround with this data object. You should always try to play around with private or protected object.
Hope this will help you.
If i'm not mistaken:
When your activity is launched, the onCreate() method is called.
But when you come back to the same activity from another activity, then the onCreate method is skipped and onResume() method is called..so my suggestion is to initialize in the onResume() method
#Override
protected void onResume(Bundle savedInstanceState) {
overridePendingTransition(R.anim.fadein, R.anim.fadeout);
setContentView(R.layout.startpage);
rowItems = new ArrayList<RowItem>();
//... Filling this array.
}
This answer might not solve your current problem ( not enough code to give a suggestion) but will help you head in the right direction.
Do provide a central data store for your objects, you should consider using singleton design pattern. Also, since the data will be accessed from multiple threads, you should make the arraylist (in your case) thread safe.
Note: if you are using synchronized list, you should lock the object to prevent access when it is iterated.
I am getting from time to time testing my app error:
03-04 20:57:01.929: E/TestApp(13673): android.view.ViewRoot$CalledFromWrongThreadException: Only the original thread that created a view hierarchy can touch its views.
From questions like this: Whats this exception?, and my own experience (I got this same error from time to time as in mentioned question) I would like to ask you guys what I can do to get rid of it?
As far as I know, I can do some stuff on AsyncTask connected to View, so I don't know why I am getting this info.
This is my code:
private MyDBAdapter mySQLiteAdapter;
private ListView wordList;
private AsyncDBDownload asycn;
private ProgressDialog dbUpdate;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.smart_guide_ocr);
asycn = new AsyncDBDownload();
wordList = (ListView) findViewById(R.id.wordsList);
//...
}
#Override
protected void onResume() {
super.onResume();
asycn.execute(null);
}
private class AsyncDBDownload extends AsyncTask<String, Integer, String> {
#Override
protected String doInBackground(String... params) {
try {
refreshList();//upload of contetn and set of adapter
} catch (Exception ex) {
Log.e(TAG, ex.toString());
}
return null;
}
#Override
protected void onPostExecute(String result) {
dbUpdate.dismiss();
}
#Override
protected void onPreExecute() {
dbUpdate = ProgressDialog.show(TestAppActivity.this, "Wait",
"DB download");
}
}
private void refreshList() {
mySQLiteAdapter = new MyDBAdapter(TestAppActivity.this);
mySQLiteAdapter.open();
String[] columns = { MyDBAdapter.KEY_TRANSLATED, MyDBAdapter.KEY_WORD, MyDBAdapter.KEY_LANG,
MyDBAdapter.KEY_ID };
Cursor contentRead = mySQLiteAdapter.getAllEntries(false, columns,
null, null, null, null, MyDBAdapter.KEY_ID, null);
startManagingCursor(contentRead);
Log.d(TAG, Integer.toString(contentRead.getCount()));
RowItem adapterCursor = new RowItem(this, R.layout.save_word_row,
contentRead, columns, new int[] { R.id.translatedWord, R.id.orgWord, R.id.langInfo }, 0);
wordList.setAdapter(adapterCursor);
mySQLiteAdapter.close();
}
You must not call wordList.setAdapter(adapterCursor); from within refresList method. That's a way of "changing a view from a non-UI thread".
So, instead, save the adapterCursor instance and use it from within the onPostExecute method.
You can not manipulate your Views within a background task. Do all the loading you need in your AsyncTask, pass it back into the activity in onPostExecute and set your adapter then. Doing any form of UI manipulation in a background task or service will throw this error.
I have spent many hours looking for a solution to this and need help.
I have a nested AsyncTask in my Android app Activity and I would like to allow the user to rotate his phone during it's processing without starting a new AsyncTask. I tried to use onRetainNonConfigurationInstance() and getLastNonConfigurationInstance().
I am able to retain the task; however after rotation it does not save the result from onPostExecute() to the outer class variable. Of course, I tried getters and setters. When I dump the variable in onPostExecute, that it is OK. But when I try to access to the variable from onClick listener then it is null.
Maybe the code will make the problem clear for you.
public class MainActivity extends BaseActivity {
private String possibleResults = null;
private Object task = null;
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
this.task = getLastNonConfigurationInstance();
setContentView(R.layout.menu);
if ((savedInstanceState != null)
&& (savedInstanceState.containsKey("possibleResults"))) {
this.possibleResults = savedInstanceState
.getString("possibleResults");
}
if (this.possibleResults == null) {
if (this.task != null) {
if (this.task instanceof PossibleResultWebService) {
((PossibleResultWebService) this.task).attach();
}
} else {
this.task = new PossibleResultWebService();
((PossibleResultWebService) this.task).execute(this.matchToken);
}
}
Button button;
button = (Button) findViewById(R.id.menu_resultButton);
button.setOnClickListener(resultListener);
}
#Override
protected void onResume() {
super.onResume();
}
OnClickListener resultListener = new OnClickListener() {
#Override
public void onClick(View v) {
Spinner s = (Spinner) findViewById(R.id.menu_heatSpinner);
int heatNo = s.getSelectedItemPosition() + 1;
Intent myIntent = new Intent(MainActivity.this,
ResultActivity.class);
myIntent.putExtra("matchToken", MainActivity.this.matchToken);
myIntent.putExtra("heatNo", String.valueOf(heatNo));
myIntent.putExtra("possibleResults",
MainActivity.this.possibleResults);
MainActivity.this.startActivityForResult(myIntent, ADD_RESULT);
}
};
private class PossibleResultWebService extends AsyncTask<String, Integer, Integer> {
private ProgressDialog pd;
private InputStream is;
private boolean finished = false;
private String possibleResults = null;
public boolean isFinished() {
return finished;
}
public String getPossibleResults() {
return possibleResults;
}
#Override
protected Integer doInBackground(String... params) {
// quite long code
}
public void attach() {
if (this.finished == false) {
pd = ProgressDialog.show(MainActivity.this, "Please wait...",
"Loading data...", true, false);
}
}
public void detach() {
pd.dismiss();
}
#Override
protected void onPreExecute() {
pd = ProgressDialog.show(MainActivity.this, "Please wait...",
"Loading data...", true, false);
}
#Override
protected void onPostExecute(Integer result) {
possibleResults = convertStreamToString(is);
MainActivity.this.possibleResults = possibleResults;
pd.dismiss();
this.finished = true;
}
}
#Override
protected void onSaveInstanceState(Bundle outState) {
super.onSaveInstanceState(outState);
if (this.possibleResults != null) {
outState.putString("possibleResults", this.possibleResults);
}
}
#Override
public Object onRetainNonConfigurationInstance() {
if (this.task instanceof PossibleResultWebService) {
((PossibleResultWebService) this.task).detach();
}
return (this.task);
}
}
It is because you are creating the OnClickListener each time you instantiate the Activity (so each time you are getting a fresh, new, OuterClass.this reference), however you are saving the AsyncTask between Activity instantiations and keeping a reference to the first instantiated Activity in it by referencing OuterClass.this.
For an example of how to do this right, please see https://github.com/commonsguy/cw-android/tree/master/Rotation/RotationAsync/
You will see he has an attach() and detach() method in his RotationAwareTask to solve this problem.
To confirm that the OuterClass.this reference inside the AsyncTask will always point to the first instantiated Activity if you keep it between screen orientation changes (using onRetainNonConfigurationInstance) then you can use a static counter that gets incremented each time by the default constructor and keep an instance level variable that gets set to the count on each creation, then print that.
I have a database with one row of data that will be used across a number of activities. I need to be able to keep the row id available in all activites so I can read and write data across different activites with my DB adapter. I have successfully used putExtra (Overthelimit.java) via an intent to pass a row id to the next activity. mRowId variable is then given the row id using getExtra (Profile.java). The problem I now have is making mRowId available to other activities i.e. MyUsual and DrinksList so I can update data as I go.
You can see I have tried putExtras, putSerializable but can't get it to work. I think I am missing some understanding.
So for my profile menu option in the activity below I can send the value of the cursor row id to Profile class:
public class Overthelimit extends ListActivity {
private OverLimitDbAdapter dbHelper;
private Cursor cursor;
/** Called when the activity is first created. */
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
this.getListView();
dbHelper = new OverLimitDbAdapter(this);
dbHelper.open();
fillData();
registerForContextMenu(getListView());
}
#Override
protected void onActivityResult(int requestCode, int resultCode,
Intent intent) {
super.onActivityResult(requestCode, resultCode, intent);
fillData();
}
private void fillData() {
cursor = dbHelper.fetchAllUserDrinks();
startManagingCursor(cursor);
//cursor.getCount();
String[] from = new String[] { OverLimitDbAdapter.KEY_USERNAME };
int[] to = new int[] { R.id.label };
// Now create an array adapter and set it to display using our row
SimpleCursorAdapter notes = new SimpleCursorAdapter(this,
R.layout.user_row, cursor, from, to);
setListAdapter(notes);
}
#Override
protected void onDestroy() {
super.onDestroy();
if (dbHelper != null) {
dbHelper.close();
}
}
#Override
public boolean onCreateOptionsMenu(Menu menu) {
MenuInflater inflater = getMenuInflater();
inflater.inflate(R.menu.main_menu, menu);
return true;
}
#Override
public boolean onOptionsItemSelected(MenuItem item) {
// Handle item selection
switch (item.getItemId()) {
case R.id.profile:
Intent myIntent1 = new Intent(this, Profile.class);
if(cursor.getCount() != 0) {
//Toast.makeText(getApplicationContext(), "no profile",Toast.LENGTH_SHORT).show();
myIntent1.putExtra(OverLimitDbAdapter.KEY_ROWID, cursor.getString(cursor.getColumnIndexOrThrow(OverLimitDbAdapter.KEY_ROWID)));
}
startActivityForResult(myIntent1, 0);
return true;
case R.id.myusual:
Intent myIntent2 = new Intent(this, MyUsual.class);
startActivityForResult(myIntent2, 0);
return true;
case R.id.trackme:
Intent myIntent3 = new Intent(this, TrackMe.class);
startActivityForResult(myIntent3, 0);
return true;
case R.id.moreinfo:
Intent myIntent4 = new Intent(this, MoreInfo.class);
startActivityForResult(myIntent4, 0);
return true;
}
return super.onOptionsItemSelected(item);
}
}
Then make it available as mRowId in my Profile activity below:
mRowId = (bundle == null) ? null :
(Long) bundle.getSerializable(OverLimitDbAdapter.KEY_ROWID);
if (mRowId == null) {
Bundle extras = getIntent().getExtras();
mRowId = extras != null ? Long.parseLong(extras.getString(OverLimitDbAdapter.KEY_ROWID))
: null;
}
I then need to make this mRowId available to another activity called DrinkList from MyUsual. so I have MyUsual below with a drink1 button onClickListener to try and send the row id to DrinksList:
public class MyUsual extends Activity {
private Long mRowId;
private OverLimitDbAdapter mDbHelper;
private Cursor cursor;
private TextView mDrink1Label;
private TextView mDrink1Units;
/** Called when the activity is first created. */
#Override
public void onCreate(final Bundle bundle) {
super.onCreate(bundle);
mDbHelper = new OverLimitDbAdapter(this);
mDbHelper.open();
setContentView(R.layout.my_usual);
mDrink1Label = (TextView) findViewById(R.id.drink1Label);
mDrink1Units = (TextView) findViewById(R.id.drink1Units);
Button drink1 = (Button) findViewById(R.id.drink1Button);
// get intent data i.e. which drink button pressed and mRowId
mRowId = (bundle == null) ? null :
(Long) bundle.getSerializable(OverLimitDbAdapter.KEY_ROWID);
if (mRowId == null) {
Bundle extras = getIntent().getExtras();
mRowId = extras != null ? Long.parseLong(extras.getString(OverLimitDbAdapter.KEY_ROWID))
: null;
}
//populateFields();
drink1.setOnClickListener(new View.OnClickListener() {
public void onClick(View view) {
setResult(RESULT_OK);
//finish();
Intent myIntent1 = new Intent(view.getContext(), DrinksList.class);
myIntent1.putExtra("drinkButton", "drink1");
if(cursor.getCount() != 0) {
myIntent1.putExtra(OverLimitDbAdapter.KEY_ROWID, cursor.getString(cursor.getColumnIndexOrThrow(OverLimitDbAdapter.KEY_ROWID)));
}
startActivityForResult(myIntent1, 0);
}
});
}
protected void onSaveInstanceState(Bundle outState) {
super.onSaveInstanceState(outState);
//saveState();
outState.putSerializable(OverLimitDbAdapter.KEY_ROWID, mRowId);
}
}
From DrinksList I select a drink and I need to use the mRowId write the data to the database via the onListItemclick:
public class DrinksList extends ListActivity {
private ProgressDialog m_ProgressDialog = null;
private ArrayList<CreateDrinkOption> m_drinks = null;
private DrinkAdapter m_adapter;
private Runnable viewDrinks;
private String drinkButton;
private Long mRowId;
private OverLimitDbAdapter mDbHelper;
private String databaseRow;
private Cursor cursor;
/** Called when the activity is first created. */
#Override
public void onCreate(Bundle bundle) {
super.onCreate(bundle);
setContentView(R.layout.drinks_list);
mDbHelper = new OverLimitDbAdapter(this);
mDbHelper.open();
m_drinks = new ArrayList<CreateDrinkOption>();
this.m_adapter = new DrinkAdapter(this, R.layout.drink_row, m_drinks);
setListAdapter(this.m_adapter);
viewDrinks = new Runnable(){
#Override
public void run() {
getDrinks();
}
};
Thread thread = new Thread(null, viewDrinks, "MagentoBackground");
thread.start();
m_ProgressDialog = ProgressDialog.show(DrinksList.this,
"Please wait...", "Retrieving data ...", true);
// get intent data i.e. which drink button pressed and mRowId
mRowId = (bundle == null) ? null :
(Long) bundle.getSerializable(OverLimitDbAdapter.KEY_ROWID);
if (mRowId == null) {
Bundle extras = getIntent().getExtras();
drinkButton = extras.getString(drinkButton);
mRowId = extras != null ? Long.parseLong(extras.getString(OverLimitDbAdapter.KEY_ROWID))
: null;
}
}
protected void onSaveInstanceState(Bundle outState) {
super.onSaveInstanceState(outState);
//saveState();
outState.putSerializable(OverLimitDbAdapter.KEY_ROWID, mRowId);
}
private Runnable returnRes = new Runnable() {
#Override
public void run() {
if(m_drinks != null && m_drinks.size() > 0){
m_adapter.notifyDataSetChanged();
for(int i=0;i<m_drinks.size();i++)
m_adapter.add(m_drinks.get(i));
}
m_ProgressDialog.dismiss();
m_adapter.notifyDataSetChanged();
}
};
#Override
protected void onListItemClick(ListView l, View v, int position, long id)
{
try
{
super.onListItemClick(l, v, position, id);
CreateDrinkOption bkg = (CreateDrinkOption)l.getItemAtPosition(position);
String drink1type = bkg.getDrinkType().toString();
float drink1units = (bkg.getPercentageByVolume() * bkg.getVolume());
//Toast.makeText(this, mRowId.toString(), Toast.LENGTH_LONG).show();
mDbHelper.updateDrink(mRowId, drink1type, drink1units);
finish();
}
catch(Exception ex)
{
Toast.makeText(this, "error", Toast.LENGTH_LONG).show();
}
}
private void getDrinks(){
try{
m_drinks = new ArrayList<CreateDrinkOption>();
CreateDrinkOption o1 = new CreateDrinkOption();
o1.setDrinkType("Beer - 1 pint");
o1.setPercentageByVolume((float) 4.5);
o1.setVolume((float) 0.5);
m_drinks.add(o1);
CreateDrinkOption o2 = new CreateDrinkOption();
o2.setDrinkType("Wine - small glass");
o2.setPercentageByVolume((float) 12);
o2.setVolume((float) 0.125);
m_drinks.add(o2);
CreateDrinkOption o3 = new CreateDrinkOption();
o3.setDrinkType("Spirit - single");
o3.setPercentageByVolume((float) 40);
o3.setVolume((float) 0.25);
m_drinks.add(o3);
CreateDrinkOption o4 = new CreateDrinkOption();
o4.setDrinkType("Alcopop - bottle");
o4.setPercentageByVolume((float) 5);
o4.setVolume((float) 0.275);
m_drinks.add(o4);
Thread.sleep(1000);
Log.i("ARRAY", ""+ m_drinks.size());
} catch (Exception e) {
Log.e("BACKGROUND_PROC", e.getMessage());
}
runOnUiThread(returnRes);
}
private class DrinkAdapter extends ArrayAdapter<CreateDrinkOption> {
private ArrayList<CreateDrinkOption> items;
public DrinkAdapter(Context context, int textViewResourceId, ArrayList<CreateDrinkOption> items) {
super(context, textViewResourceId, items);
this.items = items;
}
#Override
public View getView(int position, View convertView, ViewGroup parent) {
View v = convertView;
if (v == null) {
LayoutInflater vi = (LayoutInflater)getSystemService(Context.LAYOUT_INFLATER_SERVICE);
v = vi.inflate(R.layout.drink_row, null);
}
CreateDrinkOption o = items.get(position);
if (o != null) {
TextView tt = (TextView) v.findViewById(R.id.drinkdetail);
TextView bt = (TextView) v.findViewById(R.id.drinkunits);
if (tt != null) {
tt.setText("Type: "+o.getDrinkType());
}
if(bt != null){
bt.setText("Units: "+ String.valueOf(o.getPercentageByVolume() * o.getVolume()));
}
}
return v;
}
}
}
Sorry for the long post, but all I need to do is make this value for mRowId available to all activites so I can read/write data at any point. The data also needs to be there if the app is paused or interupted by say an incoming call, so I use onSaveInstanceState.
ok, thanks. So reply to great answers and I have done this, but it crashes trying to get the data. I have this as my Application class:
public class OverthelimitApplication extends Application {
private Long rowId;
public Long getRowId() {
return rowId;
}
public void setRowId(Long value) {
rowId = value;
}
}
then set value with this:
OverthelimitApplication app1 = (OverthelimitApplication)getApplicationContext();
app1.setRowId((long) cursor.getColumnIndexOrThrow(OverLimitDbAdapter.KEY_ROWID));
then try to get value with this and it crashes:
mRowId = ((OverthelimitApplication) getApplicationContext()).getRowId();
I have fixed it! using this the set and get:
app1.setRowId(Long.parseLong(cursor.getString(cursor.getColumnIndexOrThrow(OverLimitDbAdapter.KEY_ROWID))));
mRowId = (long)((OverthelimitApplication)getApplicationContext()).getRowId();
I still had to specify long when setting and getting. Thanks for all your input.
Another way is to create a application class which is available for all activities.
To do that, you have to extend you Manifest with
<application
..
android:name=".MyApplication" >
and create a new Class
public class MyApplication extends Application {
public int rowId = 0;
}
inside the activities, you can access the rowId by
int mRowId = ((MyApplication) getApplicationContext()).rowId;
There are two options that I think are fit for your purpose:
SharedPreferences: the added benefit is that your variables will kept and available next time you start the application. You can store primitive types easily in shared preferences, like your rowId.
Application: you can subclass the application class, something like MyApplication extends Application, declare in your manifest that you're using this class instead of the default application, and access it using getApplication from all your activities. The added benefit is you can store anything, even a complex data structure in the application, you define the member and access methods in your MyApplication class. For example you could store the whole row of data in your application, not just the rowId)
Personally, I use SharedPreferences to remember settings that I want to be saved for the user, and not having to set them again each time the application is started is nice. And I use application for all the temporary data that I want to live across all activities as long as the application is open.
I'll describe 2 ways.
1) Use a static variable in any one of the Activities. This is the quick, dirty and lazy way. You've been warned.
2) Create your Application class.
Create a Simple class MyApplication that extends Application
In the Android Manifest, there should be a field for Application, make sure you choose your Class.
Typical example.
public class MyApp extends Application
{
private Object myGloballyAccessibleObject; //make getter and setter
private static MyApp singleInstance = null;
public static MyApp getInstance()
{
return singleInstance;
}
#Override
public void onCreate() {
super.onCreate();
singleInstance = this;
}
}
In your activities,
Call this
MyApp myApp = MyApp.getInstance();
myApp.getMyAwesomeObject(); //Booyaah!
You can use the ApplicationContext too. In your Manifest, you should have something like this :
<application
...
android:name="xx.xx.MyApp"
...>
Now, you can access to the Application from any Activity thanks to :
MyApp application = (MyApp)this.getApplicationContext();
You can put your attributes in this class, it'll be accessible anywhere in your app. MyApp must extends Application. See Manifest and
Application
Here you want to get mRowId values from all activity and it is primitive types, So
Either use Shared Preferences for store data or make your member field as a static globally, Then you can use this data in your whole application life cycle..
EDIT: Also you can use Application class as a singleton for your application and create field mRowId in this class and also make getter setter method for this field..