Develop Reference

Refresh Activity

This is my scenario
Activity A (List of user)
Activity B (User Add Activity)
Desired Flow in app
Step 1: A ==> B
Step 2: B ==> A
Step 3 (Required flow):
Activity A has to reload itself or call loadListView() function after Activity B exits or is closed.
onCreate(){
.......
....
btnAddClient.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
Intent intent = new Intent( ActivityA.this, ActivityB.class);
startActivity(intent);
}
});
loadListView();
......
....
}

Try to call loadListView() in onStart or onResume methods. It will refresh the list when you come back to your activity

Getting a result from an activity
From your Activity A, call the Activity B using the startActivityForResult() method.
int RESULT_CODE = 123;
Intent intent = new Intent(this, ActivityB.class);
startActivityForResult(intent, RESULT_CODE);
Now in your ActivityA class, write the following code for the onActivityResult() method.
#Override
protected void onActivityResult(int requestCode, int resultCode, Intent data) {
super.onActivityResult(requestCode, resultCode, data);
if (requestCode == RESULT_CODE) {
if(resultCode == Activity.RESULT_OK){
bool status=data.getBooleanExtra("isUserAdded");
if(status)
{
loadListView();
}
}
}
} //onActivityResult
Return back to ActivityA with status.
Intent returnIntent = new Intent();
returnIntent.putExtra("isUserAdded",true);
setResult(Activity.RESULT_OK,returnIntent);
finish();

Start activity for result not work, between different activities

I have the main page where the photo is loaded, depending on what the array on the other page contains, in order to synchronize them I used StartActivityForResult();.
It will works like this: MainActivity has a photo, i press showMore button(open showMoreActivity), at showMoreActivity change text and after i finish showMoreActivity, MainActivity load the new photo depends on new text, but real it doesn`t change photo.
Can you help me? Where the mistake is?
buttonShowMore.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
Intent intent = new Intent(getActivity(), ShowMore.class);
onStop();
getActivity().startActivityForResult(intent, 1);
}
});
onClick button ShowMore Listener
#Override
public void onActivityResult(int requestCode, int resultCode, Intent data) {
if (data == null) {return;}
String dataStringExtra =data.getStringExtra("name1");
Picasso.get().load( dataStringExtra + ".jpg").into(imageViewFirstOfCurrentList);
}
onActivityResult method
Intent intent = new Intent();
intent.putExtra("name1", List.get(0).toString());
setResult(RESULT_OK, intent);
finish();
when close showMore Activity

try removing call to onStop() in your onClick() method

Move data by intent without startActivity

I have 2 Activities. On 2nd activity i have data which i want to move by button "Back" to 1st Activity.
Usually i moving by something like this:
button12.setOnClickListener(new View.OnClickListener() {
public void onClick(View view) {
pass=editText2.getText().toString();
Intent intent = new Intent(FirstActivity.this, MapsActivity.class);
intent.putExtra("pass_value", pass);
startActivity(intent);
}
});
But now i dont want to start Activity, instead of this i want close Activity, so i need to use finish()
Currently i created this, but no working:
b2.setOnClickListener(new View.OnClickListener() {
public void onClick(View view) {
Intent intent = new Intent(MainActivity.this, FirstActivity.class);
intent.putExtra("number", numberOfTrue);
finish();
}
});
I need something more in this code, but i dont know what.

Start a new activity with
Intent intent = new Intent(FirstActivity.this, MapsActivity.class);
intent.putExtra("pass_value", pass);
startActivityForResult(intent,1)
You can use setResult method to acheive your desired result
Intent output = new Intent();
output.putExtra("number", numberOfTrue);
setResult(Activity.RESULT_OK, output);
finish();
get Your result in FirstActivity
#Override
protected void onActivityResult(int requestCode, int resultCode, Intent data) {
if (requestCode == 1 && resultCode == Activity.RESULT_OK && data != null) {
int num = data.getIntExtra("pass_value");
}
}

b2.setOnClickListener(new View.OnClickListener() {
public void onClick(View view) {
finish();
Intent intent = new Intent(this, FirstActivity.class);
intent.putExtra("number", numberOfTrue); }});

You need to open by function startActivityForResult
startActivityForResult(Intent intent, int requestCode)
And get the data returned in the function
onActivityResult
As an example you can see a face to the camera for a picture

Android, Get result from third activity

In first activity, there is empty ListView and Button.
When I press button, it starts second activity that has ListView of categories.
After I click into one of listElements it will start third activity that has ListView with elements that are belong to my chosen category.
When I choose element of third ListView it must send me back to first activity, where my chosen element is added to my empty ListView

Use Intent.FLAG_ACTIVITY_FORWARD_RESULT like this:
FirstActivity should start SecondActivity using startActivityForResult().
SecondActivity should start ThirdActivity using this:
Intent intent = new Intent(this, ThirdActivity.class);
intent.addFlags(Intent.FLAG_ACTIVITY_FORWARD_RESULT);
startActivity(intent);
finish();
This tells ThirdActivity that it should return a result to FirstActivity.
ThirdActivity should return the result using
setResult(RESULT_OK, data);
finish();
At that point, FirstActivity.onActivityResult() will be called with the data returned from ThirdActivity.

Though I'd implore you to change your architecture design, it is possible to do it like this:
File ActivityOne.java
...
startActivityForResult(new Intent(this, ActivityTwo.class), 2);
...
#Override
public void onActivityResult(int requestCode, int resultCode, Intent data) {
if(resultCode == RESULT_OK && data != null) {
//Collect extras from the 'data' object
}
}
...
File ActivityTwo.java
...
startActivityForResult(new Intent(this, ActivityTwo.class), 3);
...
#Override
public void onActivityResult(int requestCode, int resultCode, Intent data) {
if(resultCode == RESULT_OK && data != null) {
setResult(resultCode, data);
finish();
}
setResult(RESULT_CANCELLED);
}
...
File ActivityThree.java
...
//Fill the Intent resultData with the data you need in the first activity
setResult(RESULT_OK, resultData);
finish();
...

how to handle a getIntent() method with java nullpointerexception

I have 2 activities in my application, Activity1 and Activity2.When the app launches Acitivity1 is the the one that is called.Clicking on a button in Activity1 should take you to Activity2.
In Acivity2,some data processing is done then i send back data to Activity1 using an intent like this:
Intent in=new Intent(getApplicationContext(), Activity1.class);
in.putExtra("data", data);
startActivity(in);
Then getting back to Activity1 i obtain the intent data:
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity1);
String data =(getIntent().getExtras().getString("data"));
The problem here is that the first time the app launches it checks for the intent data and it does not exist so i get the nullpointerexception error.how can i make sure it checks for the intent data when Activity2 is the previous class?

You can check if the intent is existing using:
getIntent().hasExtra("data");
This will return you a boolean.
Also if oyu want to return some datas to the first activity, your should start the second one with startActivityForResult

if (extras != null) {
if (extras.containsKey("data")) {
boolean hasData = extras.getBoolean("data", false);
// TODO: Do something with the value of "data".
}
}

put a check over it
if(getIntent().getExtras()!=null){
String data =(getIntent().getExtras().getString("data"));
}

Follow the following steps
1: from your activity1's button click call as follow
Intent i = new Intent(this, SecondActivity.class);
startActivityForResult(i, 1);
2: In your Activity2 set the data which you want to return back to Activity1 as follow and if you don't want to return back don't set anything.
Intent returnIntent = new Intent();
returnIntent.putExtra("result",result);
setResult(RESULT_OK,returnIntent);
finish();
if you don't want to return data:
Intent returnIntent = new Intent();
setResult(RESULT_CANCELED, returnIntent);
finish();
3: now again in your Activity1 handle the return data as follow
protected void onActivityResult(int requestCode, int resultCode, Intent data) {
if (requestCode == 1) {
if(resultCode == RESULT_OK){
String result=data.getStringExtra("result");
}
if (resultCode == RESULT_CANCELED) {
//Write your code if there's no result
}
}
}
EDIT:
and if you strictly want to use your own method as in your question try this:
in your Activity1 you obtain the intent data as:
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity1);
String data ="default value";
try{
data =(getIntent().getExtras().getString("data"));
}catch(Exception e){
}
}

use ActvityForResult.
replace these codes.
in ACTVITY1:
put this after onCreate:
#Override
protected void onActivityResult(int requestCode ,int resultCode ,Intent data ) {
super.onActivityResult(requestCode, resultCode, data);
String name =data.getStringExtra("data");
if(resultCode == RESULT_OK){
switch(requestCode){
case 2:
if(resultCode == RESULT_OK){
Toast.makeText(this, name, Toast.LENGTH_LONG).show();
}
}
}
in ACTIVITY2:
Intent intent=new Intent();
intent.putExtra("data",data);
setResult(2,intent);
finish();