I have two activities (A and B). Activity A calls activity B. Activity B has Back (Up) button like this:
getSupportActionBar().setDisplayHomeAsUpEnabled(true);
Now when this UP button is pressed, onCreate of activity A is again called. In the activity A, there is a classId variable (which I got from an Intent) which I want to retain. For this I have following code in my onCreate of activity A:
if (savedInstanceState == null)
{
Intent intent = getIntent();
classId = intent.getIntExtra("CLASS_ID", 0);
}
else
{
classId = savedInstanceState.getInt("CLASS_ID");
}
I have also overriden the onSavedInstanceState method:
#Override
protected void onSaveInstanceState(Bundle savedInstanceState)
{
savedInstanceState.putInt("CLASS_ID", classId);
super.onSaveInstanceState(savedInstanceState);
}
I am following this SO answer:
onCreate being called on Activity A in up navigation
The problem I am facing is that when I come again to activity A by passing back button in activity B, onCreate gets called and I found savedInstanceState to be NULL.
Edit:
Is there any other way to save my classId variable so that when I return again to activity A, I can use that?
Edit 2
If I set launch mode of my activity A to SingleTop in the manifest file, my issue gets resolved. Is it the right approach?
You should not suppose that onSaveInstanceState called each time you go to next activity.See the docs
This method is called before an activity may be killed so that when it comes back some time in the future it can restore its state. For example, if activity B is launched in front of activity A, and at some point activity A is killed to reclaim resources, activity A will have a chance to save the current state of its user interface via this method so that when the user returns to activity A, the state of the user interface can be restored via onCreate(Bundle) or onRestoreInstanceState(Bundle).
You may further consult with official docs here
Try this
public class SingletonHolder {
//your id here as what data type you want
private static SingletonHolder instance;
public static SingletonHolder getInstance() {
if (instance == null) {
instance = new SingletonHolder();
}
return instance;
}
//set getter setter here
}
If not successfull feel free to comment
I changed the launchMode of the activity A to singleTop in the mainfest file like this:
android:launchMode="singleTop"
I followed this question on SO: Setting launchMode="singleTask" vs setting activity launchMode="singleTop"
By using this approach, activity A is not destroyed and when I just finish the activity B or click UP navigation in activity B, the existing instance of activity A is launched again.
Related
I need a method to differentiate between activity launches from the launcher or another activity's up navigation. I have a setting preference to show a tutorial the next time the app is started, but the tutorial is called when I press up on the settings activity.
I've tried the methods described here (using intent.getAction() and intent.getCategories()) Differentiating between an Activity launch from home screen or from another activity from App but they don't work when I use up navigation instead of the back button
Just define global static boolean and set it true eg. isLaunch=true on your main activity and apply condition to check if isLaunch = true before calling method that displays tutorial and set it to false if it is true
public class MainActivity{
private static boolean isLaunch = true;
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
if(isLaunch){
isLaunch = false;
YourTutorialDisplayingMethod();
}
}
}
check the activity lifecycle method.OnCreate() is called only once when your activity is launched.But if you start a new activity from this activity without finishing it,then coming back from the newly opened activity using up navigation wont call the onCreate of your acticity
I am trying to save the state of the activity in android.Basic scenario is there is 2 activities A and B.Activity A contains 2 edittext fields.User enters some value into it and moves to activity B via intent.When user comes back to Activity A (by intent i have provided a back button) I need to display those values in the 2 edittext fields that the user had entered (i.e maintain the state of activity A).Also i do not want to use shared preferences or make those fields as static.
I have used the following code but it does not help:
#Override
protected void onCreate(Bundle savedInstanceState)
{
super.onCreate(savedInstanceState);
setContentView(R.layout.manual_entry);
edittext1=(Edittext)findViewById(R.id.edittext1);
}
#Override
protected void onSaveInstanceState(Bundle savedInstanceState)
{
super.onSaveInstanceState(savedInstanceState);
savedInstanceState.putString("cardvalue_saved_inst", value_card_manuallyentered);
}
#Override
public void onRestoreInstanceState(Bundle savedInstanceState)
{
super.onRestoreInstanceState(savedInstanceState);
value_savedinstance = savedInstanceState.getString("cardvalue_saved_inst");
Log.e("value_savedinstance",""+value_savedinstance);
edittext1.setText(value_savedinstance);
}
In ActivityA, if you launch ActivityB and don't call finish() on yourself, when ActivityB finishes (when user presses BACK button or otherwise), ActivityA will be shown in the same state that it was in. This is just standard Android behaviour and you don't need to do anything special.
onRestoreInstanceState() is not called if a paused activity gets resumed (which is the usual case where ActivityA launches ActivityB and ActivityB then finishes).
onRestoreInstanceState() is only called if Android killed your activity (during orientation change for example) or killed your process. In that case, when the user returns to your activity, Android will create a new instance of the activity and then call onRestoreInstanceState().
I had to simply call finish() in Activity B and it worked.
Having trouble passing data between activities.
ListActivity is collecting data and when back button is pressed returns to MainActivity and then want to get that data via onResume method but I don't get anything.
How can this problem be solved?
ListActivity.java
#Override
public void finish() {
i = new Intent(ArrayListActivity.this, MainActivity.class);
i.putParcelableArrayListExtra(Constants.TAG_SELECTED_PRODUCT_LIST, selected_list);
super.finish();
}
MainActivity.java
#Override
protected void onResume() {
super.onResume();
Bundle extras = getIntent().getExtras().getBundle(Constants.TAG_SELECTED_PRODUCT_LIST);
if(extras != null) {
selected_list = extras.getParcelableArrayList(Constants.TAG_SELECTED_PRODUCT_LIST);
myListView.setAdapter(new ProductAdapter(MainActivity.this,
R.layout.array_lisviewt_item_row, selected_list));
}
}
You probably want to start your second activity from the first one via the startActivityForResult(...) method.
This method allows you to transport results from a launched activity back to it's launching activity.
From the documentation:
Launch an activity for which you would like a result when it finished.
When this activity exits, your onActivityResult() method will be
called with the given requestCode. Using a negative requestCode is the
same as calling startActivity(Intent) (the activity is not launched as
a sub-activity).
You'll want to start the activity with startActivityForResult() and override onActivityResult() to handle the data you return from the second Activity.
Check out this article on the Android developers site for more info.
Perhaps you should
Call your ListActivity with startActivityForResult(), from your MainActivity.
Once you finished working on the ListActivity, you call setResult() to set the data, followed by finish().
This will bring you back to your previous MainActivity. So how do you retrieve the data set by your ListActivity?
In MainActivity, override onActivityResult().
There's a brief explanation of this mechanism in Starting Activities and Getting Results.
I am using android tab based application with TabGroupActivity, the application have a ListActivity "A" which drills down to a detail activity "D", on detail activity when i click device back button it navigate back to ListActivtiy "A" and relaods the data (ProgressBar shows progress on back button).
How can i avoid reloading of data on back buttuon ?
Any help would be appreciated.
Perhaps you can use onSaveInstanceState() to save what's needed to be saved and then restore your activity in onCreate()
If you look at the Activity LifeCycle :
When you go to another activity, and press back, it will call finish(). The first activity was on the onStop() method because it was no longer visible. So, when you come back to the first activity, it will call the method onStart(), and on Stop().
Try to overload this method without calling the super method (it might be a very bad idea).
You can also try to remember the position when you was (get the index of the current tab), and on the onResume() method, set the current tab to this index.
You just need an int attribute savedPosition in your listactivity.
private int savedPosition = -1;
#Override
protected void onPause() {
savedPosition = getListView().getFirstVisiblePosition();
super.onPause();
}
#Override
protected void onResume() {
super.onResume();
if(savedPosition != -1) {
getList().setSelection(savedPosition);
}
}
I have a tabhost on my application and I'm using an Activity group which handles 3 activities inside.
Example:
ActivityGroup Handles
A -> B -> C
When i start this activities i'm using the flag Intent.FLAG_ACTIVITY_CLEAR_TOP.
My problem is when the user goes from A->B->C and press back button, my B activity shows up, but it does not resume or reload or refresh. It has the same state as before.
For example if the user goes again to C, C is refreshed, but when from C goes back.... B is not.
On B I have implementend methods such as onResume, onStart, onReestart and debugging it the main thread never goes in there...
And i need to refresh B because C can make changes that change the content displayed on B.
I have googleled this for 3 days and I couldn't found a solution..
I had this problem too.
I was using ActivityGroup code based on this blog post.
When I pressed the back button the pervious View would load fine, but the activity associated with it would not fire the onResume().
I was using an extended activity with on overridden and public onResume().
I found this blog post, so tried casting the view as my extended activity and called onResume().
Bingo.
Edit.... here's some more detail...
public class YFIMenuListActivity extends ListActivity {
....
#Override
public void onResume() {
super.onResume();
}
....
}
onResume() is normally protected, but I override it and make it public so that my ActivityGroup can call it.
I only have extended list activities in this activity group (I was just playing around). If you have different activities, each will have to override onResume() and I guess you'd have to look at the type of context you got back from v.getContext() before casting and calling it.
My ActivityGroup looks something like this:
public class BrowseGroup extends ActivityGroup {
.....
#Override
protected void onResume() {
super.onResume();
// call current activity's onResume()
View v = history.get(history.size()-1);
YFIMenuListActivity currentActivity = (YFIMenuListActivity)v.getContext();
currentActivity.onResume();
}
....
}
I've managed to implement an expanded version of cousin_itt's approach.
In both of my activities being used within the activity group I changed onResume from :
protected void onResume()
to
public void onResume()
I then wrote the following onResume function in my ActivityGroup to manually fire off onResumes:
#Override
protected void onResume() {
super.onResume();
View v = history.get(history.size()-1);
MainPeopleView currentActivity = null;
try {
currentActivity = (MainPeopleView)v.getContext();
currentActivity.onResume();
}
catch ( ClassCastException e ) {
Log.e(TAG, e.toString());
}
ProfileView otherActivity = null;
try {
otherActivity = (ProfileView)v.getContext();
otherActivity.onResume();
}
catch ( ClassCastException e ) {
Log.e(TAG, e.toString());
}
}
I have to say, this feels like the worst android hack I've ever written. I'm never using activitygroup again.
((ReportActivity)getLocalActivityManager().getActivity("ReportActivity")).onResume();
ReportActivity is that name you want to back Activity
ps: v.getContext();
only return the ActivityGroup ,it can't invoke child Activity onResume
I have found that onFocusChanged(boolean hasFocus) is great for situations like ActivityGroup. This will fire, even if onResume() does not. I use it for a few of my apps that have TabHosts and ActivityGroups. Here you can force the refresh and insure that it always gets fired when your Activity regains the focus.
I hope you have write your refresh data code in this method onResume().