Develop Reference

Finish the fragment while moving to other activity?

I have a main activity that contains 3 fragments. In each fragment I have a listView, on clicking which it is diverted to a new activity.
In the new Activity, I am changing the list view content that is clicked and diverting back to the main activity using intent.
This opens a new main Activity fragment and when I press back button I again get back to the previous Main Activity that was opened earlier.

Save activity's context in static variable like this
public class MainActivity extends AppCompatActivity {
public static MainActivity mainActivityInstance;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_staff_login);
//finishing older loaded mainActivity
if(MainActivity.mainActivityInstance!=null){
MainActivity.mainActivityInstance.finish();
}
mainActivityInstance=this;
}
}
From other activities you can finish your older activity like this
if(MainActivity.mainActivityInstance!=null){
MainActivity.mainActivityInstance.finish();
}

Instead of using startActivity use startActivityForResult in your fragment and have onActivityResult to obtain result from new Activity you have started
In your fragment do like this
static final int NEXT_ACTIVITY = 100;
//insert in listview on click
Intent intent = new Intent(context,Activity2.class);
intent.putExtra("key","value");//if needed
startActivityForResult(intent,NEXT_ACTIVITY);
#Override //*Note* you must override this method in you parent Activity in order to reflect the data inside your fragment
protected void onActivityResult(int requestCode, int resultCode, Intent data) {
super.onActivityResult(requestCode,resultCode,data);//while using inside fragment
switch(requestCode) {
case NEXT_ACTIVITY:
if (resultCode == RESULT_OK) {
Bundle res = data.getExtras();
String result = res.getString("param_result");
Log.d("FIRST", "result:"+result);
}
break;
}
}
In your new Activity while finishing/onBackpressed
Bundle data = new Bundle();
data.putString("param_result", "Thanks Thanks");
setResult(RESULT_OK, data);
finish();

For fragments, instead of finish();, you should call
getActivity().finish();

Updating list in one class after action in another

I have a problem where by I have two activities, activity 1 and activity 2. Activity 1 contains a listview of contents in my SQLite database, activity 2 contains a button that when pressed preforms a query on the database. This query when run will alter the information in activity 1's list.
When I press the button the query works fine but the listview in activity 1 does not get updated. I know I have to use notifyDataSetChanged on the listview in order to have the list information updated.
My problem is how do I call this method on the list in activity 1 from the button listener in activity 2?
Listview and adapter in activity 1
String[] columns = new String[] {adapter.KEY_CONTENTS_NAME, adapter.KEY_CONTENTS_MEASUREMENT, adapter.KEY_CONTENTS_UNIT};
int[] to = new int[] {R.id.ingredientName, R.id.ingredientMeasurement, R.id.ingredientUnit};
SimpleCursorAdapter myCursorAdapter = new SimpleCursorAdapter(this,R.layout.row2, cursor, columns, to, 0);
ListView ingredientList = (ListView) findViewById(R.id.ingredientList);
ingredientList.setAdapter(myCursorAdapter);
Button in activity 2
Button cookButton = (Button) findViewById(R.id.cookButton);
cookButton.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
//simple SQL query
//call to activity 2 to update the list
}
});

You can use startActivityForResult to achieve this.
In your first activity when you want to start the second activity like this using startActivityForResult.
Intent myIntent = new Intent(FirstActivity.this, SecondActivity.class);
int FIRST_ACTIVITY_CODE = 100
startActivityForResult(intent, FIRST_ACTIVITY_CODE);
In your second activity when doing the click you want to setResult okay and then quit the activity to return to the first activity.
Button cookButton = (Button) findViewById(R.id.cookButton);
cookButton.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
//simple SQL query
setResult(RESULT_OK);
finish();
}
});
In your first activity you have to override onActivityResult and then update your list.
#Override
public void onActivityResult(int requestCode, int resultCode, Intent data) {
super.onActivityResult(requestCode, resultCode, data);
if (requestCode == FIRST_ACTIVITY_CODE) {
myCursorAdapter.notifyDataSetChanged();
}
}
So you can communicate with activities by using onActivityResult. If you want to pass the data you got back from your SQL query in the second activity to your first activity you can use setResult(int resultCode, Intent data)

Then write this function in your list activity:
#onResume
public void onResume(){
super.onResume();
myCursorAdapter.notifyDataSetChanged();
}
As you go back to that activity, this function will be called and you can notify about the changes here by calling notifyDataSetChanged.

You could start activity using startActivityForResult. Here is the documentation and an example: http://developer.android.com/training/basics/intents/result.html
On the first activity you should have something like this:
#Override
protected void onActivityResult(int requestCode, int resultCode, Intent data) {
if (requestCode == SECOND_ACTIVITY_REQUEST_CODE) {
if (resultCode == RESULT_OK) {
// load data from db
// add data to the list view (create a new adapter or clear the items from the old one and add the new items)
// notifyDataSetChanged on adapter
}
}
}
Before calling notifyDataSetChanged. Load again info from db (and check if it was updated) and add it to the list view. Then call notifyDataSetChanged

How to pass Parcelable object from child to parent activity?

I'm building a small app that requiere authentication. In my main activity I have a Parcelable class named "user" that contains the username and password of an user, when a user click on a button it starts a new activity passing that user class. It works like a charm, in the child activity the user fill the form to authenticate, then when user press the back button, I would like to send the "user" class back to my main activity.
Is it possible to do that ??

Start your child activity with:
startActivityForResult(startIntent, 1);
In your child activity, intercept the back button and append your data:
#Override
public void onBackPressed() {
Intent data = new Intent();
data.putExtra("key", yourDataHere);
setResult(Activity.RESULT_OK, data);
super.onBackPressed();
}
And get data inside parent activity inside onActivityResult
#Override
protected void onActivityResult(int requestCode, int resultCode, Intent data) {
super.onActivityResult(requestCode, resultCode, data);
if(requestCode == 1 && resultCode == Activity.RESULT_OK){
DataType yourData = (DataType) data.getParcelableExtra("key");
//Do whatever you want with yourData
}
}

How to get access to back button in android?

Can you please clarify me, what's the best practice for this example:
Activity1 does INSERTS on SQLite and starts Activity2.
On Activity2, the user clicks on Back button and goes back to Activity1.
But instead of making INSERT, I want to make UPDATE to the data on SQLite.
How do I control, that user "came" back?
What's the best practice?

Assume on button click you starting Activity 2
public static final int YOURCONSTANTNUMBER = 77;
//Button Value
Button second = (Button)findViewById(R.id.firstButton);
second.setOnClickListner(this);
#Override
public void onClick(View v)
{
switch(v.getId())
{
case R.id.btnSecondActivity:
//Code for inserting data into database
Intent secondactivity = new Intent(FirstActivity.this, SecondActivity.class);
startActivity(secondactivity);
break;
}
}
In your second activity
To take control over the back button use the below code
#Override
public void onBackPressed()
{
//Code for update
}
EDIT
Call your second activity with startActivityForResult() method which will let you know the result.
In First Activity
Intent secondactivity = new Intent(FirstActivity.this, SecondActivity.class);
startActivityForResult(secondactivity,YOURCONSTANTNUMBER);
Getting Result
#Override
protected void onActivityResult(int requestCode, int resultCode, Intent data) {
super.onActivityResult(requestCode, resultCode, data);
switch(requestCode)
{
case YOURCONSTANTNUMBER:
// It will execute if you returning from second activity
//Update you database here
}
}
In Your Second Activity
Call this method were appropriate setResult(YOURCONSTANTNUMBER);
Hope it helps

Assuming you want to do both DB operations in Activity1, consider startActivityForResult() here:
http://developer.android.com/reference/android/app/Activity.html#startActivityForResult(android.content.Intent, int)

restart activity in android

I have one activity A, that has one button and one list view which shows names of books . on click of the button, activity B starts, there user fill the book form and save it . when he press back button , user comes to activity A. Here the book name should be updated in listview. I think I have to write some code in onResume() . Can u please tell me what to write. I am using customised list view.

Start activity B with startActivityForResult() and use method onActivityResult() to restart or process the new data
For example, to start Activity B:
String callingActivity = context.getLocalClassName();
Intent newActivity = new Intent(getApplicationContext(),ActivityB.class);
newActivity.setData(Uri.parse(callingActivity));
startActivityForResult(newActivity, 0);
Then somewhere in your Activity A class:
protected void onActivityResult(int requestCode, int resultCode, Intent data){
if(requestCode == 0){
// do processing here
}
}
The other answers should suffice, but onResume() can be called in cases where the activity is resumed by other means.
To simply restart Activity A when user presses back button from Activity B, then put the following inside the onActivityResult:
if(requestCode == 0){
finish();
startActivity(starterintent);
}
And in the onCreate of Activity A, add starterintent = getIntent();
Just remember to initiate the variable with Intent starterintent; somewhere before your onCreate is called.
e.g.
public class ActivityA extends ListActivity {
Intent starterintent;
public void onCreate(Bundle b){
starterintent = getIntent();
}
protected void onActivityResult(int requestCode, int resultCode, Intent data){
if(requestCode == 0){
finish();
startActivity(starterintent);
}
}
private void startActivityB(){
String callingActivity = context.getLocalClassName();
Intent newActivity = new Intent(getApplicationContext(),ActivityB.class);
newActivity.setData(Uri.parse(callingActivity));
startActivityForResult(newActivity, 0);
}
}
Then just call startActivityB() from a button click or whatever

YES you are right. Write code in onResume.
When you updated date just call notifyDataSetChanged(); for your ListView adapter
Hope, it help you!

You can either start the activity when user press on Save, and it will fix it for you.
Or if you want to press back:
#Override
public void onResume(){
super.onResume();
list.clear();
list.addAll(getBooks());
adapter.notifyDataSetChanged();
}