Develop Reference

how to define callback for my program in android Studio?

I want to define callback for a Notebook program that way after note saved in EditActivity,in Main Activity Update list of notes,But This does not happen.
EditActivity:
public interface OnClickDoneListener{
void onClickDone();
}
public void setOnClickDoneListener(OnClickDoneListener onClickDoneListener){
this.onClickDoneListener=onClickDoneListener;
}
btnDone.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View view) {
if (extras != null) {
myDatabase.updateRow(id, txtTitle.getText().toString(), txtDesc.getText().toString());
NoteModel noteModel = new NoteModel();
noteModel.setTitle(txtTitle.getText().toString());
noteModel.setDesc(txtDesc.getText().toString());
Intent intent = new Intent(EditActivity.this, MainActivity.class);
startActivity(intent);
onClickDoneListener.onClickDone();
} else {
Done();
}
}
});
Main Activity:
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
Toolbar toolbar = findViewById(R.id.toolbar);
setSupportActionBar(toolbar);
setupViews();
getDataFromDB();
recyclerView.setAdapter(new NoteAdapter(MainActivity.this,dataList));
noteAdapter = new NoteAdapter(MainActivity.this,dataList);
recyclerView.setAdapter(noteAdapter);
fabAdd = (FloatingActionButton)findViewById(R.id.fab_main_add) ;
EditActivity editActivity = new EditActivity();
editActivity.setOnClickDoneListener(new EditActivity.OnClickDoneListener() {
#Override
public void onClickDone() {
noteAdapter.notifyDataSetChanged();
}
});
please help me.
My English is poor,sorry for it.

You want your data to be updated when the MainActivity is shown, right ?
You just have to call your getDataFromDB part in onResume() instead of onCreate()

EditActivity editActivity = new EditActivity();
editActivity.setOnClickDoneListener(new EditActivity.OnClickDoneListener() {
#Override
public void onClickDone() {
noteAdapter.notifyDataSetChanged();
}
});
What you are doing here is setting the value of OnClickDoneListener in a new instance of EditActivity that you will never use. Because when you use new Intent(MainActivity.this, EditActivity.class) to start the EditActivity it will create a new instance of EditActivity and your interface would be null.
I suggest you use android's Broadcast Receiver instead of a callback in this case. All you have to do is:
In MainActivity: You will need to instantiate a broadcast receiver. You need to register it onCreate or onStart and unregister it onStop or onDestory.
In EditAcitivity: You send a broadcast whenever you want to notify your MainActivity to update the list.
Check out this example:
https://riptutorial.com/android/example/18305/communicate-two-activities-through-custom-broadcast-receiver

How to remove Specific activity/activities from activity stack based on some action?

I am working on an application where i need to navigate to specific activity based on some actions. Here is a image
Here my first activity is the ReadingActivity. Based on some actions user will be taken to the NewProjectReadingActivity. There the user will have Two options.
Option One
Option Two
Based on the options chosen by the user he/she will be taken to the ReadingInputActivity. After taking the input from the ReadingInputActivity the user will be forwarded to the ReadingConfirmationActivity. There will be three options
Option One
Option Two
Option Three
If the user selects the Option One then he/she will be taken to the ReadingActivity which is very easy. I will clear the stack and start the ReadingActivity again and there if he/she presses the back button the app will be minimized which is totally fine. But if the user selects Option Two then he/she will be taken to the NewProjectReadingActivity.If i clear the activity stack and start NewProjectReadingActivity again then it will start the NewProjectReadingActivity but the problem is that if the user presses the back button it will minimize my app as it is the only Activity present in the activity stack.
What i want is that if the user selects Option Two on the ReadingConfirmationActivity then the user will be taken to the NewReadingActivity that means i want to remove ReadingConfirmationActivity (which is easy just call the finish()) and the activity started before that activity i,e ReadingInputActivity.
Every Activity mentioned above is hosting a fragment. I am providing the activity code below.
ReadingActivity
public class ReadingActivity extends BaseAppCompatActivity {
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
if( savedInstanceState == null ) {
getSupportFragmentManager().beginTransaction().replace(R.id.fragment_container, ReadingFragment.getInstance(), ReadingFragment.TAG).commit();
}
setDisplayHomeAsUpEnabled(true);
setActionBarText(getString(R.string.new_project_reading));
}
#Override
protected void setupContentView() {
setContentView(R.layout.activity_reading);
}
public static Intent newIntent(Context context) {
Intent intent = new Intent(context, ReadingActivity.class);
return intent;
}
}
NewProjectReadingActivity
public class NewProjectReadingActivity extends BaseAppCompatActivity {
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
if( savedInstanceState == null ) {
getSupportFragmentManager().beginTransaction().replace(R.id.fragment_container, NewProjectReadingFragment.getInstance(), NewProjectReadingFragment.TAG).commit();
}
setDisplayHomeAsUpEnabled(true);
setActionBarText(getString(R.string.new_project_reading));
}
#Override
protected void setupContentView() {
setContentView(R.layout.activity_new_project_reading);
}
public static Intent newIntent(Context context) {
Intent intent = new Intent(context, NewProjectReadingActivity.class);
return intent;
}
}
ReadingInputActivity
public class ReadingInputActivity extends BaseAppCompatActivity {
private static final String EXTRA_VALUE_TYPE = "value_type";
private int valueType = 0;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
valueType = getIntent().getIntExtra(EXTRA_VALUE_TYPE, 0);
if( savedInstanceState == null ) {
getSupportFragmentManager().beginTransaction().replace(R.id.fragment_container, ReadingInputFragment.getInstance(valueType), ReadingInputFragment.TAG).commit();
}
setDisplayHomeAsUpEnabled(true);
setActionBarText(getString(R.string.reading_input));
}
#Override
protected void setupContentView() {
setContentView(R.layout.activity_reading_input);
}
public static Intent newIntent(Context context, int valueType) {
Intent intent = new Intent(context, ReadingInputActivity.class);
intent.putExtra(EXTRA_VALUE_TYPE, valueType);
return intent;
}
}
ReadingConfirmationActivity
public class ReadingConfirmationActivity extends BaseAppCompatActivity {
private static final String EXTRA_VALUE_TYPE = "value_type";
private static final String EXTRA_READING_VALUE = "reading_value";
private int valueType = 0;
private double readingValue = 0;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
valueType = getIntent().getIntExtra(EXTRA_VALUE_TYPE, 0);
readingValue = getIntent().getDoubleExtra(EXTRA_READING_VALUE, 0);
if( savedInstanceState == null ) {
getSupportFragmentManager().beginTransaction().replace(R.id.fragment_container, ReadingConfirmationFragment.getInstance(valueType, readingValue), ReadingConfirmationFragment.TAG).commit();
}
setDisplayHomeAsUpEnabled(true);
setActionBarText(getString(R.string.reading_input));
}
#Override
protected void setupContentView() {
setContentView(R.layout.activity_reading_confirmation);
}
public static Intent newIntent(Context context, int valueType, double readingValue) {
Intent intent = new Intent(context, ReadingConfirmationActivity.class);
intent.putExtra(EXTRA_VALUE_TYPE, valueType);
intent.putExtra(EXTRA_READING_VALUE, readingValue);
return intent;
}
}

You wrote:
What i want is that if the user selects Option Two on the
ReadingConfirmationActivity then the user will be taken to the
NewReadingActivity that means i want to remove
ReadingConfirmationActivity (which is easy just call the finish()) and
the activity started before that activity i,e ReadingInputActivity.
To do this you will do the following when the user selects Option Two in ReadingConfirmationActivity:
Intent intent = new Intent(this, NewReadingActivity.class);
intent.addFlags(Intent.FLAG_ACTIVITY_CLEAR_TOP);
startActivity(intent);
This will cause all of the activities on top (and including) NewReadingActivity to be finished. A new instance of NewReadingActivity will be created and shown to the user. If you wish to return to the existing instance of NewReadingActivity, you can also do that by also adding Intent.FLAG_ACTIVITY_SINGLE_TOP to the Intent.

Put And Get Extras From Another Class

I have Act_01 (where I put value) and Act_02 (where I get value) but have declared these methods in a Extras class, getting value from Act_02 returns null value:
Act_01: (Where I want to pass the value Name to Act_02)
public class Act_01 extends Activity {
Extras cc_Extras;
Button btn1;
Intent intent;
String str_Name;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.act_01);
cc_Extras = new Extras();
str_Name = "Buck";
btn1 = (Button) findViewById(R.id.btn1);
btn1.setOnClickListener(new View.OnClickListener() {
public void onClick(View v) {
cc_Extras.putExtras();
startActivity(intent);
}
});
}
}
Act_02: (Where I want ot receive value Name from Act_01 but the app crashes with null value)
public class Act_02 extends Activity {
Extras cc_Extras;
String str_Name;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.act_02);
cc_Extras = new Extras();
if(getIntent() != null && getIntent().getExtras() != null)
{
cc_Extras.getExtras();
}
Toast.makeText(getApplicationContext(), "Name: "+str_Name, Toast.LENGTH_SHORT).show();
}
}
Extras: (Where I define the methods to put and get Extras)
public class Extras extends Activity {
String str_Name;
Intent intent;
public void putExtras() {
// TODO Auto-generated method stub
intent.putExtra("KEY_Name", str_Name);
}
public void getExtras() {
// TODO Auto-generated method stub
str_Name = getIntent().getExtras().getString("KEY_Name");
}
}
EDIT: I do not want to pass and get data directly between activities, I want to use the 3rd class (Extras.java) because I have too many activities having too many values between each other and want to sort of define them globally in Extras so that all my other activities can just call one method instead of getting and putting too many values in my activities.

Your app crashes not with a null value, but a null pointer reference because you created a new Activity manually
cc_Extras = new Extras();
Then called a lifecycle method on it
cc_Extras.getExtras()
Which calls getIntent(), but the Intent was never setup by the Android framework, and cc_Extras.getExtras() wouldn't have any of the data you wanted anyway in the second Activity because it was just created there, not from the first Activity.
Briefly, you should never make a new Activity, and your Extras class does not need to be an Activity in the first place (nor does it provide much benefit).
Just use the Intent object provided by the first Activity to start the second Activity, and get extras like normal. Don't overcomplicate your code. Regarding the title of the question, Intent and Bundle are already "another class" designed by Android for you to transfer data.

On both activities you are creating a new instances of Extras class means they dont hold the same value you can do this to transfer data from A to B
public class Act_01 extends Activity {
Button btn1;
Intent intent;
String str_Name;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.act_01);
str_Name = "Buck";
btn1 = (Button) findViewById(R.id.btn1);
btn1.setOnClickListener(new View.OnClickListener() {
public void onClick(View v) {
intent = new Intent(Act_01.this, Act_02.class);
intent.putExtra("data", str_Name)
startActivity(intent);
}
});
}
}
And receieve data like this
public class Act_02 extends Activity {
String str_Name;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.act_02);
// cc_Extras = new Extras();
if(getIntent() != null)
{
if (getIntent().getStringExtra("data") != null) {
Toast.makeText(Act_02.this, "Name: "+getIntent.getStringExtra("data"), Toast.LENGTH_SHORT).show();
}
}
}
}
Also you should consider using Activity Context instead of the application context

Ok! so here are the few things I might wanna suggest you to correct.
Changes needs to be done in the code.
You are not assigning anything to "intent" object , and you have passed a intent without assigning anything to it.
Your instance cc_Extra isn't doing anything in the activity1. You might wanna pass the "intent" object in your constructor of class like cc_Extras= new Extras(intent); and in the Extras class do the following- Intent intent;
Extras(Intent i)
{
this.intent=i;
}
In the activity2 you are creating the new Instance of Extras(). So according to your code it is going to be NULL by default. If you have done the changes from the previous step, you can create new instance by doing cc_Extras(getIntent());
Corrections in the code
1) In Extras class getExtras() method instead of str=getIntent() use str=intent.getExtras.getString().
2) In the activity2 you are not assigning anything to your String str_Name, so you need to return the string you got in getExtras() method. You can do it by changing the return type to String. Below is the sample code.
public String getExtras()
{
str_Name=intent.getExtras().getString("KEY_Name");
//OR
//str_Name=intent.getStringExtra("KEY_Name");
return str_Name;
}
3) By the doing this you need to catch this string in the activity2 by doing `
if(getIntent() != null && getIntent().getExtras() != null)
{
str_Name=cc_Extras.getExtras();
}`
4) Another thing is you must create intent like this-
Intent intent=new Intent(currentActivityName.this,anotherActivity2.class);
//then use the intent object
EDIT- Your code must look like this in the end...
Act1
public class Act_01 extends Activity {
Extras cc_Extras=null;
Button btn1;
String str_Name;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.act_01);
str_Name = "Buck";
btn1 = (Button) findViewById(R.id.btn1);
btn1.setOnClickListener(new View.OnClickListener() {
public void onClick(View v) {
//changes to do
Intent intent= new Intent(Act01.this,Act02.class);
cc_Extras= new Extras(intent);
cc_Extras.putExtras(str_Name);
//end
startActivity(intent);
}
});
}
}
Act02
public class Act_02 extends Activity {
Extras cc_Extras;
String str_Name;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.act_02);
cc_Extras = new Extras(getIntent());
if(getIntent() != null && getIntent().getExtras() != null)
{
str_Name=cc_Extras.getExtras();
}
Toast.makeText(getApplicationContext(), "Name: "+str_Name, Toast.LENGTH_SHORT).show();
}
}
Extras class
public class Extras { //remove "extends Activity" because it is a class not a activity
String str_Name;
Intent intent;
Extras(Intent i)
{
this.intent=i;
}
public void putExtras(String str) {
// TODO Auto-generated method stub
str_Name=str;
intent.putExtra("KEY_Name", str_Name);
}
public String getExtras() {
// TODO Auto-generated method stub
str_Name = intent.getExtras().getString("KEY_Name");
return str_Name;
}
}
Above code will work just on String. You can extend the functionality if you want.
I hope this must work to get your code working!

Passing Object with multiple parts from one activity to another

Hi I have a Requirement like Person Details for that i have multiple details like personal,educational,job like In first activity am enter personal details and then educational and then job like that one after another for that how can i maintain all details in single object and pass through app please help me.

Be aware that you need to bundle an object in an Intent, that object must implement the Parcelable interface. Here's a common implementation taken from the Parcelable documentation...
public class MyParcelable implements Parcelable {
private int mData;
public int describeContents() {
return 0;
}
public void writeToParcel(Parcel out, int flags) {
out.writeInt(mData);
}
public static final Parcelable.Creator<MyParcelable> CREATOR
= new Parcelable.Creator<MyParcelable>() {
public MyParcelable createFromParcel(Parcel in) {
return new MyParcelable(in);
}
public MyParcelable[] newArray(int size) {
return new MyParcelable[size];
}
};
private MyParcelable(Parcel in) {
mData = in.readInt();
}
}
Once you've done that, simply pass the object around in an Intent...
Intent i = new Intent(getApplicationContext(), ACTIVITY_TO_START.class);
i.putExtra("extra_key", new MyParcelable());
startActivity(i);
to retrieve the object for the starting activity...
Bundle extras = getIntent().getExtras();
if(extras != null && extras.containsKey("extra_key"))
{
MyParcelable p = (MyParecelable)extras.getParcelable("extra_key");
}

Simple solution: Use intents for this
Personal.class
public class Personal extends Activity {
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.personal);
Intent i = new Intent(getApplicationContext(), Educational.class);
i.putExtra("personal_details",<-get data from object->);
startActivity(i);
}
}
Educational.class
public class Personal extends Activity {
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.personal);
String personal_details;
Bundle extras = getIntent().getExtras();
if (extras != null) {
personal_details= extras.getString("personal_details");
}
Intent i = new Intent(getApplicationContext(), educational.class);
i.putExtra("personal_details",personal_details);
i.putExtra("educational_details",<-get data from object->);
startActivity(i);
}
}
Job.class
public class Personal extends Activity {
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.personal);
String personal_details,educational_details;
Bundle extras = getIntent().getExtras();
if (extras != null) {
personal_details= extras.getString("personal_details");
educational_details= extras.getString("educational_details");
}
Intent i = new Intent(getApplicationContext(), FinalResult.class);
i.putExtra("personal_details",personal_details);
i.putExtra("educational_details",educational_details);
i.putExtra("job_details",<-get data from object->);
startActivity(i);
}
}
FinalResult.class
public class Personal extends Activity {
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.personal);
String personal_details,educational_details,job_details;
Bundle extras = getIntent().getExtras();
if (extras != null) {
personal_details= extras.getString("personal_details");
educational_details= extras.getString("educational_details");
job_details= extras.getString("job_details");
}
}
}
{EDIT-1}
have a look at one of my answers in different storage options in
android - Click Here
You can achieve it using application variable or shared
preferences but i would not recommend it. !
Try storing it in POJO(Plain old Java class)
{EDIT-2}
Hmm if i understand correctly your question:: You are connected to internet(Wifi,Wired,... etc) basically you are trying to show a dialog when there is no network connectivity ! .... You can take the help of Broadcast receivers ...
Try this:: Set the broadcast receiver to fire the intent when there is no net connectivity ....
Write the code to catch that intent and pop the dialog .... In this dialog give the user option to reconnect the connectivity !

How to call startactivityforresult from a non-activity class to get the resuts

Is it possible to call startActivityForResult() from a non-activity class to get the results?
Scenario is something like this:
I have a class NonActivity (it doesn't derive from Activity as its not a UI).
This class will have bunch of functions(steps basically) to run.
One of the steps requires to show UI(Activity) and then get the result (user enter something).
Then been able to use that data in next following steps.
How can this be achieved without deriving from activity class as I don't have UI component?
Also since I don't want to derive from activity class that means I cannot override OnActivityResult(). Where results actually come from?

startActivityForResult() is only available from real on-screen activities, since it is a method in, well, Activity. Please redesign your application so that the user interface is driven from activities.
On the other hand, if your non Activity class is initialized and used from an onscreen Activity, you could pass that instance of the Activity to your class as a parameter in the constructor and use it to launch other Activities.
Be careful though. Using this method increases the risk of a memory leak, as the external class (Utils in my example) might keep a reference to the Activity even after its gone.
If all you want to do is access data, then you could try writing it to SharedPreferences or a Database or some files and then using the application context (passed in via a constructor again) to read it. This reduces the risk of a memory leak. Something like:
MyApiClass myApiClass = new MyApiClass(getApplicationContext());
EXAMPLE CODE
Main Activity:
public class Main extends FragmentActivity {
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
Utils util = new Utils(this);
util.startTest();
}
#Override
protected void onActivityResult(int arg0, int arg1, Intent arg2) {
Toast.makeText(this, "onActivityResult called", Toast.LENGTH_LONG).show();
super.onActivityResult(arg0, arg1, arg2);
}
}
Utils class (which launches for result):
public class Utils {
Activity activity;
public Utils(Activity ac) {
activity = ac;
}
public void startTest() {
Intent i = new Intent(activity, Test.class);
activity.startActivityForResult(i, 1);
}
}
Test Activity:
public class Test extends FragmentActivity {
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
Toast.makeText(this, "Test", Toast.LENGTH_LONG).show();
this.setResult(Activity.RESULT_OK);
this.finish();
}
}

StartActivityForResult from a class using a fragment with no visible GUI. You might find something like this in a utility class.
see runGetUserAccount below. It creates its own fragment and executes a startActivityForResult. Then it has it's own onActivityResult.
public class MyGooglePlay {
private static final int CONNECTION_FAILURE_RESOLUTION_REQUEST = 31502;
private ActionBarActivity activity;
private FragmentManager fragManager;
public MyGooglePlay(ActionBarActivity activity) {
this.activity = activity;
this.fragManager = activity.getSupportFragmentManager();
}
/**
* Starts an activity in Google Play Services so the user can pick an
* account
*/
private String mEmail = "";
static final int REQUEST_CODE_PICK_ACCOUNT = 1000;
public void runGetUserAccount() {
if (TextUtils.isEmpty(mEmail)) {
// run this code in gui less fragment so we can pickup the
// on activity result from inside the mygoogleplay class.
Fragment f = new Fragment() {
#Override
public void onAttach(Activity activity) {
super.onAttach(activity);
String[] accountTypes = new String[] { "com.google" };
Intent intent = AccountPicker.newChooseAccountIntent(null,
null, accountTypes, false, null, null, null, null);
startActivityForResult(intent, REQUEST_CODE_PICK_ACCOUNT);
}
#Override
public void onActivityResult(int requestCode, int resultCode,
Intent data) {
if (requestCode == REQUEST_CODE_PICK_ACCOUNT) {
if (resultCode == Activity.RESULT_OK) {
set_Email(data
.getStringExtra(AccountManager.KEY_ACCOUNT_NAME));
// getUsername();
}
super.onActivityResult(requestCode, resultCode, data);
}
//this is to verify the fragment has been removed.
//you can log or put a breakpoint to verify
#Override public void onDestroy(){
super.onDestroy();
}
};
FragmentTransaction fragmentTransaction = this.fragManager
.beginTransaction();
fragmentTransaction.add(f, "getusername");
fragmentTransaction.commit();
}
}
/**
* #param mEmail
* the mEmail to set
*/
private void set_Email(String mEmail) {
this.mEmail = mEmail;
if (!TextUtils.isEmpty(mEmail)) {
// TODO notify caller email is ready;
// activity.onEmailReady(mEmail);
}
//we are done with the "getusername" fragment
Fragment f = fragManager.findFragmentByTag("getusername");
if (f!=null) {
fragManager.beginTransaction().remove(f).commit();
}
}
}

U should pass context as Activity,then u will get solution.
try this below code.it will work
In non Activity class
public class nonActivity {
public static void method(Activity activity)
{
Intent intent = new Intent(activity, SecondActivity.class);
activity. startActivityForResult(intent, REQUEST_CODE);
}
}
In SecondActivity
Intent intent = getIntent();
intent.putExtra("data", "data"); //here u can pass data to previous activity
setResult(RESULT_OK, intent);
finish();
In firstActivity
protected void onActivityResult(int requestCode, int resultCode, #Nullable Intent data) {
try {
super.onActivityResult(requestCode, resultCode, data);
if (requestCode == REQUEST_CODE && resultCode == RESULT_OK) {
String status = data.getStringExtra("data");
//Do what u want with data
}
} catch (Exception e) {
System.out.println("=====Exception=====" + e.toString());
}
}

If you want the result back from the activity to your normal class, supposed it is a class with a custom adapter within it.
you cannot use startActivityForResult because you are not in an activity
what I did is that i launched the activity from the class with an intent. Then I calculated or did what I have to. From this activity I send the information to the main class supposed with a method MainActivity.the_method() and in the main activity I changed the custom adapter o did what I have to using the adapter object and calling adapter.getItem(position)
Hope this can give you an idea