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Android resume activity variables gone

Short:
I have Three classes: A (MainActivity), B (Secondary), C(Third).
A is parent of B is parent of C.
In A I make an Intend with Extra int idForUsage on B. B stores idForUsage in a variable int chosenId(works fine).
B does Stuff and makes an Intent with Extra int chosenId and int secondIdForUsage(works also fine).
C does Stuff and it works all fine.
When I´m now clicking the litte "back button" in the upper left corner to get to the parent activity the app crashes because I´m trying to access the Variable chosenId which seems to being set to default -1 (even if I´m trying to read the Extra again.)
public class MainActivity extends AppCompatActivity {
//references to Buttons etc
...
public static final String ChosenID = "com.example.Abzeichenschwimmer.ChosenSwimmerID";
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
//set up button stuff
...
//ListView which has clickable Items which trigger the Activity
lv_swimmerList = findViewById(R.id.lv_schwimmerListe);
//Listeners
lv_swimmerList.setOnItemClickListener(this::onListViewItemClick);
}
#Override
protected void onResume(){
super.onResume();
updateSchwimmerliste(dataBaseHelper);
}
public void onListViewItemClick(AdapterView<?> parent, View view, int position, long id) {
SchwimmerModel clickedSchwimmer = (SchwimmerModel) parent.getItemAtPosition(position);
Intent intent = new Intent(MainActivity.this, DisplaySchwimmer.class);
//Toast.makeText(MainActivity.this, String.valueOf(clickedSchwimmer.getId()), Toast.LENGTH_SHORT).show();
intent.putExtra(ChosenSwimmerID, clickedSchwimmer.getId());
startActivity(intent);
}
}
public class DisplaySchwimmer extends AppCompatActivity {
int chosenSwimmerID;
public static final String SchwimmerID = "com.example.Abzeichenschwimmer.schwimmerID";
public static final String AufgabenID = "com.example.Abzeichenschwimmer.aufgabenID";
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_display_schwimmer);
lv_exc = findViewById(R.id.lv_aufgaben);
refreshValues();
showAufgabenOnListView(dataBaseHelper);
lv_exc.setOnItemClickListener(this::onListViewItemClick);
}
public void getIntentExtra(){
Intent intent = getIntent();
chosenSwimmerID = intent.getIntExtra(MainActivity.ChosenSwimmerID,-1);
}
public void onDeleteClick(View view){
SchwimmerModel toDeleteSwimmer = (SchwimmerModel) dataBaseHelper.getSchwimmerByID(chosenSwimmerID);
dataBaseHelper.deleteSchwimmer(toDeleteSwimmer);
Toast.makeText(this, "deleted", Toast.LENGTH_SHORT).show();
DisplaySchwimmer.this.finish();
}
public void refreshValues(){
getIntentExtra();
SchwimmerModel schwimmer = dataBaseHelper.getSchwimmerByID(chosenSwimmerID); <--- Main Error
}
private void showAufgabenOnListView(DataBaseHelper dataBaseHelper) {
getIntentExtra();
ArrayAdapter<ExcerciseModel> schwimmerArrayAdapter = new ArrayAdapter<ExcerciseModel>(DisplaySchwimmer.this, android.R.layout.simple_list_item_1, dataBaseHelper.getExcersisesForSwimmerByID(chosenSwimmerID));
lv_exc.setAdapter(schwimmerArrayAdapter);
}
public void onListViewItemClick(AdapterView<?> parent, View view, int position, long id) {
ExcerciseModel clickedExcerciseModel = (ExcerciseModel) parent.getItemAtPosition(position);
Intent intent2 = new Intent(DisplaySchwimmer.this, DisplayAufgabe.class);
intent2.putExtra(SchwimmerID, chosenSwimmerID);
intent2.putExtra(AufgabenID, clickedExcerciseModel.getId());
Log.e("aaa", String.valueOf(chosenSwimmerID));
startActivity(intent2); <-- Intentstart
}
#Override
protected void onResume(){
super.onResume();
showAufgabenOnListView(dataBaseHelper);
}
}
I hope the code (deleted many lines) is ok for an overview. Maybe someone knows the solution for this.
Thanks Maximus

When you press back from DisplayAufgabe to DisplaySchwimmer (the intent always is null)
Because you call getIntent di DisplaySchwimmer, you will get default value which is -1 (null intent extra)
When you try to call dataBaseHelper.getSchwimmerByID(chosenSwimmerID); is mean you try to get index -1 on database. You will always get error because accessing index -1.
My Suggestion
Add validation before call dbHelper i.e
if (chosenSwimmerID > -1){
SchwimmerModel schwimmer = dataBaseHelper.getSchwimmerByID(chosenSwimmerID);
}
Only getExtra when value available
if (intent.hasExtra(MainActivity.ChosenSwimmerID)){
chosenSwimmerID = intent.getIntExtra(MainActivity.ChosenSwimmerID,-1);
}

It all boiled down on using sharedPreferences. This helped a lot. A Second post from me explanined this problem more simplified and I found a solution.

Initializing variables in onCreate, but updating them in onResume()

Here is my situation:
I have an OnCreate code like the following:
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
bunz = Bunz.getInstance(); //getting instance of bunz
bunz.setBunz(50);
bunz.setMoney(0);
bunz.setIncrement(1);
Button upgradeButton = (Button) findViewById(R.id.upgradeButton);
upgradeButton.setOnClickListener(new View.OnClickListener(){
#Override
public void onClick(View view){
Intent startIntent = new Intent(getApplicationContext(), UpgradeMenu.class);
startActivity(startIntent);
}
});
moneyCount = (TextView) findViewById(R.id.moneyCount);
bunzCount = (TextView) findViewById(R.id.bunzCount);
ImageButton bun = (ImageButton) findViewById(R.id.bun);
}
Notice how in my OnCreate code, I do 2 things; first, I initialize all the values I need:
bunz.setBunz(50);
bunz.setMoney(0);
bunz.setIncrement(1);
and then I display these values on TextViews and set up some Buttons and intents:
Button upgradeButton = (Button) findViewById(R.id.upgradeButton);
upgradeButton.setOnClickListener(new View.OnClickListener(){
#Override
public void onClick(View view){
Intent startIntent = new Intent(getApplicationContext(), UpgradeMenu.class);
startActivity(startIntent);
}
});
moneyCount = (TextView) findViewById(R.id.moneyCount);
bunzCount = (TextView) findViewById(R.id.bunzCount);
ImageButton bun = (ImageButton) findViewById(R.id.bun);
I'm new to Android studio, and here is the problem I'm having. I want to use onResume() to update these values in the TextView (I update them in another activity) every time I go back to this activity. However, if I move all the code in onCreate into onResume, then every time I go back to this activity, the values will be set to 50,0, and 1. I understand I could use a boolean, so that onCreate() triggers the first time the app is launched, but onResume() doesn't trigger, and then onResume() triggers after that, and simply copy and paste the second half of the onCreate code into onResume(), but that seems inefficient, and isn't how Android studio is designed to work. Can I somehow initialize the values in another location?
I have a global Bunz class that looks like the following:
public class Bunz {
private int bunz;
private int money;
private int increment;
//singleton code
private static Bunz instance;
private Bunz(){
}
public static Bunz getInstance(){
if (instance == null){
instance = new Bunz();
}
return instance;
}
public int getBunz() {
return bunz;
}
public void setBunz(int num){
bunz = num;
}
public int getMoney(){
return money;
}
public void setMoney(int num){
money = num;
}
public int getIncrement(){
return increment;
}
public void setIncrement(int num){
increment = num;
}
}
so maybe I could initialize these values here somehow?
Thanks!

here's one thing you could alternatively do:
public static Bunz getInstance(){
if (instance == null){
instance = new Bunz();
instance.setBunz(50);
instance.setMoney(0);
}
return instance;
}
in your instance creation here, try setting the values you want here, instead of in onCreate of the app.
you could just be making the changes in the constructor as well.

While your code uses statics, which I believe is unnecessary. Statics are not your average goto solution, they come with a hefty price of an object not eligible for GC.
You can get the result from the second activity via onActivityResult method.
First, start second activity using startAtivityForResult() //This takes in a request code(Int), it can be whatever you set.
First activity
Intent intent = new Intent(this, SecondActivity.class);
startActivityForResult(intent , 100);
Second Activity
//Do you work in the second activity, generate new data
Intent returnIntent = new Intent();
returnIntent.putExtra("bunz", 100);
returnIntent.putExtra("money", 200);
returnIntent.putExtra("increment", 2);
setResult(Activity.RESULT_OK, returnIntent);
finish();
Capture Second Activity Result
This code is supposed to be written in your first activity.
#Override
protected void onActivityResult(int requestCode, int resultCode, Intent data) {
if (requestCode == 100) { //Remember the code we set in startActivityForResult? This is where we identify our work
if(resultCode == Activity.RESULT_OK){ //Code to check if data is passed
Int bunz =data.getIntExtra("bunz")
bunz.setBunz(bunz)
.....
}
}
}

How to receive data from one activity to another - android

I'm trying to send an integer from one activity to another in Android studio. In my source class I have sent the data using putExtra() and in the recipient class, I am trying to receive it using getIntent(). However, I get the error 'Could not resolve method 'getIntent()' in the recipient class. Here is my code:
I'm a total newbie to Android studio as well as Java so if I'm missing something really obvious, please be considerate.
Source Activity:
public class AugmentedImageActivity extends AppCompatActivity {
private ArFragment arFragment;
private ImageView fitToScanView;
// Augmented image and its associated center pose anchor, keyed by the augmented image in
// the database.
private final Map<AugmentedImage, AugmentedImageNode> augmentedImageMap = new HashMap<>();
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
arFragment = (ArFragment) getSupportFragmentManager().findFragmentById(R.id.ux_fragment);
fitToScanView = findViewById(R.id.image_view_fit_to_scan);
arFragment.getArSceneView().getScene().addOnUpdateListener(this::onUpdateFrame);
}
#Override
protected void onResume() {
super.onResume();
if (augmentedImageMap.isEmpty()) {
fitToScanView.setVisibility(View.VISIBLE);
}
}
/**
* Registered with the Sceneform Scene object, this method is called at the start of each frame.
*
* #param frameTime - time since last frame.
*/
private void onUpdateFrame(FrameTime frameTime) {
Frame frame = arFragment.getArSceneView().getArFrame();
// If there is no frame or ARCore is not tracking yet, just return.
if (frame == null || frame.getCamera().getTrackingState() != TrackingState.TRACKING) {
return;
}
Collection<AugmentedImage> updatedAugmentedImages =
frame.getUpdatedTrackables(AugmentedImage.class);
for (AugmentedImage augmentedImage : updatedAugmentedImages) {
switch (augmentedImage.getTrackingState()) {
case PAUSED:
// When an image is in PAUSED state, but the camera is not PAUSED, it has been detected,
// but not yet tracked.
int value=augmentedImage.getIndex();
Intent i = new Intent(AugmentedImageActivity.this, AugmentedImageNode.class);
i.putExtra("key",value);
startActivity(i);
String text = "Detected Image " + augmentedImage.getIndex();
SnackbarHelper.getInstance().showMessage(this, text);
break;
case TRACKING:
// Have to switch to UI Thread to update View.
fitToScanView.setVisibility(View.GONE);
// Create a new anchor for newly found images.
if (!augmentedImageMap.containsKey(augmentedImage)) {
AugmentedImageNode node = new AugmentedImageNode(this);
node.setImage(augmentedImage);
augmentedImageMap.put(augmentedImage, node);
arFragment.getArSceneView().getScene().addChild(node);
}
break;
case STOPPED:
augmentedImageMap.remove(augmentedImage);
break;
}
}
}
}
Recipient activity:
public class AugmentedImageNode extends AnchorNode {
private static final String TAG = "AugmentedImageNode";
// The augmented image represented by this node.
private AugmentedImage image;
private static CompletableFuture<ModelRenderable> ulCorner;
public AugmentedImageNode(Context context) {
Intent intent = getIntent();
Bundle extras = intent.getExtras();
int value = extras.getInt("key");
if (value == 0) {
// Upon construction, start loading the models for the corners of the frame.
if (ulCorner == null) {
ulCorner =
ModelRenderable.builder()
.setSource(context, Uri.parse("models/tinker.sfb"))
//.setSource(context, Uri.parse("models/borderfence-small2.sfb"))
.build();
}
}
}
#SuppressWarnings({"AndroidApiChecker", "FutureReturnValueIgnored"})
public void setImage(AugmentedImage image) {
this.image = image;
// If any of the models are not loaded, then recurse when all are loaded.
if (!ulCorner.isDone())// || !urCorner.isDone() || !llCorner.isDone() || !lrCorner.isDone())
{
CompletableFuture.allOf(ulCorner)//, urCorner, llCorner, lrCorner)
.thenAccept((Void aVoid) -> setImage(image))
.exceptionally(
throwable -> {
Log.e(TAG, "Exception loading", throwable);
return null;
});
}
// Set the anchor based on the center of the image.
setAnchor(image.createAnchor(image.getCenterPose()));
// Make the 4 corner nodes.
Vector3 localPosition = new Vector3();
Node cornerNode;
localPosition.set(-0.0f * image.getExtentX(), 0.1f, +0.5f * image.getExtentZ());
cornerNode = new Node();
cornerNode.setParent(this);
cornerNode.setLocalPosition(localPosition);
cornerNode.setLocalRotation(Quaternion.axisAngle(new Vector3(-1f, 0, 0), 90f));
cornerNode.setRenderable(ulCorner.getNow(null));
}
private void setLocalRotation() {
}
public AugmentedImage getImage() {
return image;
}
}

getIntent() method are only available in class which extends the activity[directly or indirectly]

Here is code how to use share preference in your scenario.I hope it will help you.
Instead of below code
Intent i = new Intent(AugmentedImageActivity.this, AugmentedImageNode.class);
i.putExtra("key",value);
startActivity(i);
Use this one
SharedPreferences pref = getApplicationContext().getSharedPreferences("MyPref", MODE_PRIVATE);
Editor editor = pref.edit();
editor.putInt("Key", "int value");
editor.commit();
And retrieve preference value on your AugmentedImageNode screen using below code
SharedPreferences settings = getSharedPreferences("MyPref", MODE_PRIVATE);
int snowDensity = settings.getInt("Key", 0); //0 is the default value

remove the first three lines of your AugmentedImageNode(Context context) in recipient activity and replace it with following
int value = getIntent().getIntExtra("key",0);
where 0 is just default value.

getintent is working if you are extent Activity and AppCompatActivity
for example:
MainActivity.java
choice_a.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View view) {
Intent intent=new Intent(MainActivity.this,SecondActivity.class);
//putExtra(key name,default value);
intent.putExtra("int_key",22);
startActivity(intent);
}
});
SecondActivity.java
public class SecondActivity extends AppCompatActivity {
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_second);
//get intent values
Intent intent = getIntent();
Bundle extras = intent.getExtras();
int value = extras.getInt("int_key");
Log.e("Int_Value", "" + value);
// another way
int i = getIntent().getIntExtra("int_key", 0);
Log.e("Int_Value", "" + i);
}
}
In your code you have extend AnchorNode

android : can't delete and remove sharedpreferences file

i have posting question in here but i got nothing, so i decide to make a new question for searching other solution.
this is my case : First, I was using Shared preferences for my application for sending data from one activity to another, when listview is clicked in first activity, it will going to detail. when other list is clicked, it will going to first data that i've clicked before it. then i realize if i use sharedpreferences for sending data from one activity to other activity, it will save in device memory, so i change my code and decide to use intent, but my sharedpreferences's file is not remove. when list is clicked, it will going to first data that i've clicked when i use shared preferences.
I have used:
settings.edit().clear().commit();
and
settings.edit().remove().commit();
but i think it doesn't work. this is my first activity using intent:
public class TerbaruSimasCard extends ListActivity {
String nama1,alamat1,ket1,img_id1,telp1,begdate1,enddate1;
private ProgressDialog dialog;
private ArrayList<TerbaruModel>ListTerbaru;
ListView list;
#Override
protected void onCreate(Bundle savedInstanceState) {
//hide title bar
BasicDisplaySettings.toggleTaskBar(TerbaruSimasCard.this, false);
//show status bar
BasicDisplaySettings.toggleStatusBar(TerbaruSimasCard.this, true);
SharedPreferences settings = getSharedPreferences("PREFS_NAME", 0);
settings.edit().clear().commit();
super.onCreate(savedInstanceState);
setContentView(R.layout.terbarusimascard);
ListTerbaru= new ArrayList<TerbaruModel>();
new TerbaruAsyncTask().execute();
}
public class TerbaruAsyncTask extends AsyncTask<Void, Void, String> {
String url = ("http://www.abc.xyz/sc_merchant.htm?s=3&d=25");
public TerbaruAsyncTask() {
this.url=url;
}
protected void onPreExecute (){
super.onPreExecute();
dialog = ProgressDialog.show(TerbaruSimasCard.this,"", "melakukan pengambilan data...");
}
#Override
protected String doInBackground(Void... params) {
String result = "";
try {
result= Connection.get(url);
} catch (Exception e){
result = "";
Log.d("test", e.getMessage());
}
return result;
}
#Override
protected void onPostExecute (String result){
super.onPostExecute(result);
fetchResponse(result.replace("\n","").trim());
dialog.dismiss();
ListView lv = getListView();
lv.setOnItemClickListener(new OnItemClickListener() {
#Override
public void onItemClick(AdapterView<?> parent, View view,
int position, long id) {
Intent detail= new Intent (TerbaruSimasCard.this, TerbaruDetail.class);
detail.putExtra("nama", nama1);
detail.putExtra("alamat",alamat1);
detail.putExtra("ket", ket1);
detail.putExtra("telp",telp1);
detail.putExtra("begdate", begdate1);
detail.putExtra("enddate",enddate1);
detail.putExtra("img_id", img_id1);
System.out.println(nama1);
startActivity (detail);
}
});
}
}
private void fetchResponse (String result){
if (!result.equals("")){
try {
JSONArray jsonArray = new JSONArray(result);
TerbaruModel LT=null;
for (int i= 0; i < jsonArray.length(); i++) {
JSONObject jsonObject= jsonArray.getJSONObject (i);
LT= new TerbaruModel (jsonObject.optString("kat"),
img_id1=jsonObject.optString("img_id"),
nama1= jsonObject.optString("nama"),
alamat1=jsonObject.optString("alamat"),
ket1=jsonObject.optString("ket"),
jsonObject.optString("tgl"),
jsonObject.optString("accday"),
telp1=jsonObject.optString("telp"),
begdate1=jsonObject.optString("begdate"),
enddate1=jsonObject.optString("enddate")
);
ListTerbaru.add(LT);
list=(ListView)findViewById(android.R.id.list);
setListAdapter (new TerbaruAdapter(this, ListTerbaru));
}
this is for detail:
public class TerbaruDetail extends Activity {
String nama1,alamat1,ket1,img_id1,telp1,begdate1,enddate1;
#Override
public void onCreate (Bundle savedInstanceState){
SharedPreferences settings = getSharedPreferences("PREFS_NAME", 0);
settings.edit().clear().commit();
//hide title bar
BasicDisplaySettings.toggleTaskBar(TerbaruDetail.this, false);
//show status bar
BasicDisplaySettings.toggleStatusBar(TerbaruDetail.this, true);
super.onCreate(savedInstanceState);
setContentView(R.layout.detailviewer);
Intent detail= getIntent();
nama1=detail.getStringExtra("nama");
alamat1= detail.getStringExtra("alamat");
ket1= detail.getStringExtra("ket");
img_id1= detail.getStringExtra("img_id");
telp1= detail.getStringExtra("telp");
begdate1= detail.getStringExtra("begdate");
enddate1= detail.getStringExtra("enddate");
System.out.println(nama1+"nama");
TextView detail_phone=(TextView) findViewById(R.id.detail_phone);
TextView detail_begdate=(TextView) findViewById(R.id.begdate);
TextView detail_enddate=(TextView) findViewById(R.id.endate);
TextView detail_name =(TextView) findViewById(R.id.detail_name);
TextView detail_adress =(TextView) findViewById(R.id.detail_adress);
TextView keterangan =(TextView) findViewById(R.id.keterangan);
ImageView detail_img_id= (ImageView) findViewById(R.id.img_kategori);
detail_name.setText(nama1);
detail_phone.setText(telp1);
detail_begdate.setText(begdate1);
detail_enddate.setText(enddate1);
detail_adress.setText(alamat1);
keterangan.setText(ket1);
}

If You do not mind just delete the app then reload the apk.
From what I know the Shared Preferences value will remain until you uninstall an app.
If the above did not work then try to deleted manually
/data/data/com.package.name/shared_prefs/PREFS_NAME.xml

If you just want to clear out your data (because it is corrupt or whatever), you can do that manually from the home screen. setting -> application manager -> "your app" -> clear data

SharedPreferences.Editor.clear() will not delete the sharedpreferences file, it only clears the contents in this file.
If you really want to delete this file, you should use file operation , sharedprefereces file location is /data/data/com.yourpackage.name/shared_prefs/filename.xml. BTW, you'd better use intent to send data between activities.

get/use radio button value android

I FIGURED OUT WHAT I WAS DOING. I HAD THE VARIABLE NAME IN QUOTES WITH THE REST OF THE URL STRING.
How do you save the value of a Radio button into a variable and use that variable later.
I can see the variable Day_Item in my LogCat and the value is in there but when try using Day_Item later it does not show the valuable.
Below is a section of my code that shows the buttons.
String Day_Item = null;
public class SearchDB extends Activity {
private static final String TAG = "MyApp";
String start_log = "STARTED";
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.search_layout);
final RadioButton radio_monday = (RadioButton) findViewById(R.id.monday);
radio_monday.setOnClickListener(radio_listener);
cityspinner.setOnItemSelectedListener(new OnItemSelectedListener() {
#Override
public void onItemSelected(AdapterView<?> parent, View view, int position,long arg3)
{
int id = parent.getId();
if (spinner2_count2 < spinner2_count1 ) {
spinner2_count2++; }
else
{
String city_spinner_log = "CITY SPINNER";
Log.d(TAG, city_spinner_log);
String item = cityspinner.getSelectedItem().toString();
String nameContentType = "name";
String cityURL = "GetRestaurant.php?day=Day_Item&city=" + item;
Log.d(TAG, cityURL);
String shop_data = DataCall.getJSON(cityURL,nameContentType);
Log.d(TAG, shop_data);
Bundle bundle = new Bundle();
bundle.putString("shopData", shop_data);
Intent myIntent = new Intent(SearchDB.this, ShowRestaurant.class);
myIntent.putExtras(bundle);
startActivityForResult(myIntent, 0);
}
}
}
//ONCLICKLISTENER that saves RADIO value into a variable.
public OnClickListener radio_listener = new OnClickListener() {
public void onClick(View v) {
// Perform action on clicks
RadioButton rb = (RadioButton) v;
Day_Item = (String) rb.getText();
Log.d(TAG,Day_Item);
Toast.makeText(SearchDB.this, Day_Item, Toast.LENGTH_SHORT).show();
}
};
}

You would need a bit more code to get a good solid answer. Such as how is Day_Item allocated? And is it's scope global? Are you calling it from another activity or the one it's allocated within? These are just guesses at this point:
1) Are you sure your onClickListener isn't firing multiple times? Thus setting Day_Item to an undesired text or nothing at all?
2) Rather a question/answer,
"but when try using Day_Item later it does not show the valuable"
I'm assuming this means that it is null? Well if it's being set properly, and then it is being null'd... it either is being explicitly null'd by you somewhere (such as (1)) or else the allocation and scope are the issue area I believe...