Develop Reference

How do I persist an attribute in an activity that I'm navigating back up to?

I have some activities basically set up as shown below (clicks on are ListViews).
Parent class method to go to MyChild1
public void onItemClick(int pos){
Intent i = new Intent(this, MyChild1.class);
i.putExtra("KEY1", myAdapter.getItem(pos).getId());
startActivity(i);
}
MyChild1 class method to go to MyChild2
public void onItemClick(int pos){
Intent i = new Intent(this, MyChild2.class);
i.putExtra("KEY2", myAdapter2.getItem(pos).getId());
startActivity(i);
}
So you see that I have a parent, a child, and a grandchild activity. The child inflates based on the id provided by the parent and the grandchild inflates based on the id of the child. This works fine. However, when I use up navigation from the grandchild back to the child, it no longer has the id it needs from the parent to properly inflate. I need to support up navigation because the child can change based on actions in the grandchild.
I could pass the parent's id all the way down to the grandchild activity, but I don't know how to pass it back up. How can I handle this?
Edit: More code for context.
Here is my activity's onCreate.
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_course);
if (savedInstanceState == null) {
getSupportFragmentManager().beginTransaction()
.add(R.id.container, new CourseActivityFragment()).commit();
Intent intent = getIntent();
courseId = intent.getIntExtra(MainFragment.COURSE_ID, 0);
System.out.println("the saved state was null");
// The above prints, so I know it enters this if statement
} else {
courseId = savedInstanceState.getInt(COURSE_ID);
}
}
And here is my onSaveInstanceState
#Override
public void onSaveInstanceState(Bundle savedInstanceState){
// Save current CourseId
savedInstanceState.putInt(COURSE_ID, courseId);
// Call superclass to save view hierarchy state
super.onSaveInstanceState(savedInstanceState);
}

Instead of startActivity, use startActivityForResult:
Intent intent = new Intent(ParentClass.this, ChildClass.class);
startActivityForResult(intent, RequestCode);
In child class, set some parameter in intent to identify in Parent class.
Intent intent = getIntent();
intent.putExtra(<Key>, <Value>);
In parent class, override the onActivityResult method, and check your Value for that Key
#Override
public void onActivityResult(int requestCode, int resultCode, Intent intent)
{
if (requestCode == RequestCode)
{
//Do something
}
}

I don't quite follow what you need so I hope this will help. Save it in your Activity class as member variable. Activity's object is not destroyed right after user leave this activity. If that still occur and Android will kill your activity, you can use onSaveInstanceState() and restoreInstanceState() methods to restore this id.

Coming back from intent, do something

I have an android application which is using listView. After clicking on any item on the list it shows you AlertDialog where you can chose either edit or delete. After clicking edit it starts a new intent sending some extra strings to fill up the form for editing. I would like to refresh the list after I click on button save in that EditActivity.
I have read about notifyDataSetChanged() and I think it could work I just would like to know if there is any method which is in MainClass (listView class) and it is executed right after I came back from intent, right after clicking save button in EditActivity.
Or may I just add notifyDataSetChanged() method after I start an activity in the MainActivity?

public class yourClass extends ListActivity {
//define a class variable here.
private ArrayAdapter<Friend> adapter;
#Override
public void onCreate(Bundle savedInstanceState){
//Change this line setListAdapter(new ArrayAdapter<Friend>(this, android.R.layout.simple_list_item_1, db.getAllFriends()));
to
adapter = new ArrayAdapter<Friend>(this, android.R.layout.simple_list_item_1, db.getAllFriends());
setListAdapter(adapter);
}
#Override
public void onResume(){
super.onResume();
adapter.notifyDataSetChanged();
}
}

You can add listView.notifyDataSetChanged() in your activity onResume() function.
#Override
public void onResume(){
super.onResume();
yourListView.notifyDataSetChanged();
}

Use the method startActivityForResult() when opening your EditActivity then implement onActivityResult method in your main class. There you will be able to use notifyDataSetChanged
Read this from the doc

use startActivityForResult to call your EditActivity (this isn't simplest way to do what you want but is good way to do), by using this you can find out what is the result of your edit
Intent i = new Intent(this, EditActivity.class);
startActivityForResult(i, 1);
In your EActivity set the data which you want to return back to MainActivity
Intent returnIntent = new Intent();
returnIntent.putExtra("result",YOUR_RESULT); // skip if you do not want to return special result
setResult(RESULT_OK,returnIntent);
finish();
if you want to send cancel action (in your case fail edit) use this
Intent returnIntent = new Intent();
setResult(RESULT_CANCELED, returnIntent);
finish();
Now in your MainActivity class write following code for onActivityResult() method
protected void onActivityResult(int requestCode, int resultCode, Intent data) {
if (requestCode == 1) {
if(resultCode == RESULT_OK){
String result=data.getStringExtra("result"); // result sent from EditActivity
listViewAdapter. notifyDataSetChanged();
}
if (resultCode == RESULT_CANCELED) {
//Write your code if there's no result
}
}
}//onActivityResult

Set ImageView in a static method

I have a method that needs to be called from another activity, and I need to use it to set an ImageView in it's own activity. I have this method in MainActivity:
public static void setImageView(String fileName){
Log.i(TAG, fileName);
imageView = (ImageView) findViewById(R.id.imageView);
bmp = BitmapFactory.decodeFile(fileName);
imageView.setBackgroundResource(0);
imageView.setImageBitmap(bmp);
}
But I can't make a static reference to findViewById because it isn't a static method. This method is being called in a Camera Activity after the photo has been saved, I want to pass in the fileName (file URI) and set the imageView such that when the Camera Activity finishes and the user return to the MainActivity the ImageView is already set. As such, in CameraView I am trying to call this:
...code...
mCamera.takePicture(null, null, callback);
MainActivity.setImageView(fileName);
Is there a cheeky way around this? I know there are other posts on this but I can't quite work out how to apply the advice given there to my situation.
Thanks!

Maybe you should launch your CameraActivity using startActivityForResult() method, and after take the photo put the fileName as an Extra into an Intent and set it as result. Then in your MainActivity you can get the fileName back from the Intent arg of onActivityResult().
Something like:
public class MainActivity extends Activity{
public void aMethod(){
...
Intent i = new Intent(this, CameraActivity.class);
startActivityForResult(i, REQUEST_CODE);
...
}
protected void onActivityResult(int requestCode, int resultCode, Intent data) {
if (requestCode == REQUEST_CODE && resultCode == RESULT_OK) {
Bundle b = data.getExtras();
String fileName = b.getString(RETURN_FILE_PARAMETER);
doSomething(fileName);
}
}
}
...
public class CameraActivity extends Activity{
private void returnFileFinishActivity(String fileName) {
Intent retIntent = new Intent();
retIntent.putExtra(RETURN_FILE_PARAMETER, fileName);
setResult(RESULT_OK, retIntent);
finish();
}
}
Regards.

A few things.
1) Since you should only be displaying one activity at a time, why not just start with startActivityForResult in the activity with the ImageView and override onActivityResult in your camera activity?
2) I'm not sure of your application, but it may be easier if you implement taking a picture by following this: http://mobile.tutsplus.com/tutorials/android/android-sdk-quick-tip-launching-the-camera/ .
3) You can expose a static reference to your main activity, in your main activity's onCreate method, do something like staticRef = this; and in your camera activity simply access it via MainActivity.staticRef... (I would not recommend this approach)
4) You can register a broadcast receiver in your Main activity that has a reference to your main activity or image view and in your camera activity you send a broadcast to it which you can set the image view

Passing image from activity to another activity?

I'm trying to take apicture and I want to pass this picture to another activity to be displayed in it.
OnClickListener listener_TakePic = new OnClickListener() {
#Override
public void onClick(View v) {
// TODO Auto-generated method stub
intent = new Intent(android.provider.MediaStore.ACTION_IMAGE_CAPTURE);
startActivityForResult(intent, CAMERA_PIC_REQUEST);
}
};
protected void onActivityResult(int requestCode, int resultCode, Intent data) {
if (requestCode == CAMERA_PIC_REQUEST && resultCode == RESULT_OK) {
Bitmap image = (Bitmap) data.getExtras().get("data");
}// End IF
}// End of Method
Please tell me what should I do or modify to achieve what I want..
Actually, i have created an application class "base class" in which, I have defined an "bitmap cameraPic" and "static final int CAMERA_PIC_REQUEST = 1;"
Now, I have an activity classed named "AddLocation" from which I call startActivityForResult(intent, CAMERA_PIC_REQUEST);
but I want the result of the camera Picture to appear in another activity called "MPActivity"
My question is, should I call "onActivityResult(int requestCode, int resultCode, Intent data)" method from "MPActivity" or there is no need to call it...
i'm really confused please clarify..

There are more than one way to tackle the task you are doing.
you can build a java class and put populates its one of property by the desired image. Then you can just get stuff that into an arraylist and pass that to a global arraylist.
you can use Application class and make a global image variable that can be accessed in every class in your activity.
etc ...

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();
}