Develop Reference

Restart activity instead reCreate [Android]

I have following situations with activities A,B,C:
A->B->C->A
In this last step (C->A), I want to override onBackPressed of C, so that it restarts activity A (without recreating it). I tried code below, but onCreate() of A is still called. Which flag should I add?
public void onBackPressed() {
Intent intent=new Intent(C.this, A.class);
intent.addFlags(Intent.FLAG_ACTIVITY_CLEAR_TOP);
startActivity(intent);
}

This is the best way to refresh your activity:
public void refresh() {
Intent intent = getIntent();
overridePendingTransition(0, 0);
intent.addFlags(Intent.FLAG_ACTIVITY_NO_ANIMATION);
finish();
overridePendingTransition(0, 0);
startActivity(intent);
}

OnCreate will be called, this is the correct behavior, below is from Google documentation:
When your activity is recreated after it was previously destroyed, you can recover your saved state from the Bundle that the system passes your activity. Both the onCreate() and onRestoreInstanceState() callback methods receive the same Bundle that contains the instance state information.
Because the onCreate() method is called whether the system is creating a new instance of your activity or recreating a previous one, you must check whether the state Bundle is null before you attempt to read it. If it is null, then the system is creating a new instance of the activity, instead of restoring a previous one that was destroyed.
but this does not matter if you handle it properly, for instance:
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState); // Always call the superclass first
// Check whether we're recreating a previously destroyed instance
if (savedInstanceState != null) {
// Restore value of members from saved state
mCurrentScore = savedInstanceState.getInt(STATE_SCORE);
mCurrentLevel = savedInstanceState.getInt(STATE_LEVEL);
} else {
// Probably initialize members with default values for a new instance
}
...
}

public void onBackPressed() {
Intent intent=new Intent(C.this, A.class);
// remove below Flag and while going from A dont call finish();
//intent.addFlags(Intent.FLAG_ACTIVITY_CLEAR_TOP);
startActivity(intent);
}

So you want to make sure, that activity A is in the same state as it was before you switched to activity B, right?
Have you tried using the onSaveInstanceState() / onRestoreInstanceState() (respectively onCreate(Bundle savedInstanceState)) callbacks as described in: https://developer.android.com/training/basics/activity-lifecycle/recreating.html ?
Example here: https://stackoverflow.com/a/151940/3540885
I am not sure if your desired way is possible. Usually it is better to let Android handle the lifecycle itself. Just save the important stuff whenever the system feels like destroying your activity - so you can recreate it with the last state again...
edit:
It is long ago since I last messed around with multiple activities. Have you considered using Fragments instead of multiple activities? Once I got the concept of the Fragments, I started using only one parent Activity and replacing Fragments. So all your "heavy stuff" could be instantiated once in the parent activity and accessed by the fragments who need it. This could be an alternate solution, which is IMHO worth to think about.

I like Stanojkovic answer and to save data you can pass it using the intent.
public void refresh() {
Intent intent = getIntent();
intent.putExtra("extra_id",details);
overridePendingTransition(0, 0);
intent.addFlags(Intent.FLAG_ACTIVITY_NO_ANIMATION);
finish();
overridePendingTransition(0, 0);
startActivity(intent);
}
and to get it in onCreate
details=getIntent().getStringExtra("extra_id")

Intent returning null after leaving app and coming back

If im staying in the app, this works fine
Click button to take me to new activity:
intent.putExtra("invite_id", invite_id);
startActivity(intent);
Receiving Activity:
Bundle b = getIntent().getExtras(); //invite id is in here
Now here is the weird part. If I am in the app, then click home button to leave the app and go to the native contacts app and save ANYTHING (like edit a name or number...the problem only occurs if I actually save something), then go to recent apps and open up my app from there... now if I click the button to launch my intent to take me to a new activity, the receiving activity returns a null bundle
Bundle b = getIntent().getExtras(); //returns null
Why could this be happening?

String b = getIntent().getStringExtra("invite_id");

Intent extras are always persisted across activity death and recreation. So, if you're stashing that extra value, it will continue to be there if you are resuming the app with the recent app switcher.
I would verify that you are stashing values in the intent.

simply that means that your activity being recreated so you have to options to avoid that:
Avoid recreating your activity by setting this to your Activity within the manifest
android:configChanges="keyboardHidden|orientation|screenSize|locale"
Or by saving the instance of the id you received by doing such:
#Override protected void onSaveInstanceState(Bundle outState) {
super.onSaveInstanceState(outState);
outState.putString("myId",myId);
}
#Override
protected void onCreate(Bundle savedInstanceState) {
if (savedInstanceState == null) {
myId = getIntent().getExtras().getString("myId");
}
}

save data while destroying and recreating activity

I've settings(called from onCreateOptionMenu) from my Activity which uses to update the UI on current Activity.
Starting Preferences on updating Preferences, Calling Activity needs to update UI on Preference basis.
Snippet how Preference called:-
Intent in = new Intent(this, PrefsSecondaryActivity.class);
in.putExtra("caller", "sx");
startActivityForResult(in, SECSETTINGS);
Catch to get the UI updates
if (requestCode == SECSETTINGS) {
Intent intent = getIntent();
finish();
startActivity(intent);
}
I used to Re-Create that activity with the above snippet. Inside of onCreate() of Activity. I checked the Preference Name-value Pair and update the UI which workd perfectly fine.
How to store the values which are inside that activity while destroying and recreating activity?
As I'm Destroying and Recreating activity which renders whole new Activity with no values inside of it.
I tried to set onSavedInstanceState() while calling Preferences and onRestoreInstanceState() is called in catch the onActivityResult()
Settings values in Preferences makes good change of SLOC. So it's not preferrable way right now.
Any suggestion would be welcome.

This is how I do that (I have some static variables declared in my Activity):
#Override
protected final void onRestoreInstanceState(final Bundle inState)
{
// Restore the saved variables.
isChartShown = inState.getBoolean("chart", false);
qIndex = inState.getInt("index");
scores = inState.getIntArray("scores");
}
#Override
protected final void onSaveInstanceState(final Bundle outState)
{
// Save the variables.
outState.putBoolean("chart", isChartShown);
outState.putInt("index", qIndex);
outState.putIntArray("scores", scores);
}
This code works for me. I use it for saving some state variables used to maintain the values upon rotation.
[EDIT]
Otherwise, if you force the app finishing, then you'd go for Sharedpreferences:
just save your values before finishing and reload them in onCreate.

onResume() is not called in physical device instead onCreate() is called

Iam little bit amazed with this.I have an onResume() in my activity.Its called and works well in my emulator, but in a physical device samsung galaxy note for specific with jellybean installed,its not called.Instead onCreate() is called all the time.Why this happens?
public void onResume(){
super.onResume();
if(firsttime){
try {
Toast.makeText(getApplicationContext(), "Resuming Activity",Toast.LENGTH_LONG).show();
addReminder();
} catch(Exception exception) {
exception.printStackTrace();
}
} else {
firsttime=true;
}
}
This is my code.firsttime is a static boolean variable.It is used to prevent onResume() being called when app is started for the first time

Considering your current scenario, you should save variable in preferences instead of relying on activities lifecycle since lifecycle depends on many things.
Using static variable for this scenario is bad choice in general.I think this should solve your problem.

Try to print something inside the onResume and check it in LogCat.... the code inside onResume may be causing this.
or else can you elaborate your question?

I think here is what happens,
when your app not the Top app, the activity manager actually destroy the activity, it only called
public void onSaveInstanceState(Bundle savedInstanceState)
no
onStop
called, so no
noResume
will be called.
The correct to do this is, when put all states of this activity when
public void onSaveInstanceState(Bundle savedInstanceState)
called.
and in your onCreate() function, do such thing
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState); // Always call the superclass first
// Check whether we're recreating a previously destroyed instance
if (savedInstanceState != null) {
// Restore value of members from saved state
mCurrentScore = savedInstanceState.getInt(STATE_SCORE);
mCurrentLevel = savedInstanceState.getInt(STATE_LEVEL);
} else {
// Probably initialize members with default values for a new instance
}
...
}
to check if you have some saved state.
Most code was copy from android developer site:
http://developer.android.com/training/basics/activity-lifecycle/recreating.html

onResume() not called second time an Activity is launched

During the normal course of development, I noticed that a particular activity appears to have stopped responding the second time it is called.
i.e. menu->(intent)->activity->(back button)->menu->(intent)
There is nothing relevant in logcat.
I don't even know where to start debugging this nor what code to show so here are the onClick and onResume fragments:
if (!dictionary.getClassName().equals("")) {
this.setOnClickListener(new OnClickListener() {
public void onClick(View v) {
Intent i;
i = new Intent(mContext, NVGlobeNavigatorVC.class);
i.putExtra("PAGE_TITLE", title);
i.putExtra("TITLE", _dictionary._title);
mContext.startActivity(i);
});
} else {
findViewById(R.id.greaterthan).setVisibility(View.GONE);
}
and in the Activity being launched:
#Override
protected void onResume() {
super.onResume();
...
Nothing unusual in manifest either:
<activity
android:name=".NVViews.NVGlobeNavigatorVC"
android:theme="#style/WindowTitleBackground"
android:label="GlobeNavigator"/>
For clarity, I put breakpoints on mContext.startActivity(i) and super.onResume(). I click the view with the onClickListener and both breakpoints are hit as expected. I then press the back button which returns me to the menu. onPause() is called as expected.
I touch the view to launch the activity again, and the breakpoint on startActivity is hit but not in onResume() in the target activity. The screen goes black and the only way I can get going again is to restart the app. If I pause the debugger, it pauses in dalvik.system.NativeStart() which implies that the activity is never relaunched.
I don't think it's relevant, but I'm using Intellij IDEA and have deleted all of the output directories, invalidated the caches and done a full rebuild.
Target API is 8. I've tested on 2.3 and 4.0.4.
Any ideas? I'm stumped.
[EDIT]
In onPause, I save some stuff to prefs. The purpose of onResume() is to get them back again:
#Override
protected void onPause() {
super.onPause();
SCPrefs.setGlobeViewViewPoint(globeView.getViewPoint());
SCPrefs.setGlobeViewZoom(globeView.getZoom());
SCPrefs.setGlobeViewScale(globeView.getScale());
}

This code:
i = new Intent(mContext, NVGlobeNavigatorVC.class);
creates a new intent. The intent is of class NVGlobeNavigatorVC.class.
If you call it once, you create a new activity, lets call it "iTheFirst". If you back out of the activity, it executes "on pause". When you run the above code again, you create another new activity of the same class, but a different acitivity. Hence it won't resume your other activity, but make a new one that we could call "iTheSecond". It looks just like iTheFirst but is unique.
If you want to resume the above, after backing out of it, you need to keep a reference to it in your menu. Then in your onClick, look to see if that activity exists, and if not, make a new one and start it, and if it does exist, just resume it.
Here is a sample activity that remembers and restarts an activity:
Intent savedCueCardActivity = null;
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState, R.layout.landing);
}
public void goToNextScreen(View v) {
if (savedCueCardActivity == null) {
savedCueCardActivity = new Intent().setClass(this, CueCardActivity.class);
startActivity(savedCueCardActivity);
// lastActivity.finish();
} else {
savedCueCardActivity.setFlags(Intent.FLAG_ACTIVITY_REORDER_TO_FRONT);
startActivity(savedCueCardActivity);
}
overridePendingTransition(R.anim.fade_in, R.anim.fade_out);
}

I found the problem, and it's a bit esoteric.
I have a large static data structure which is loaded in a class static initialiser. There was a bug in that initialiser causing an infinite loop the second time it was called if the data structure was still loaded.
Because that class is referenced in my Activity, the class loader is loading it before onCreate() or onResume() is called.
The loop gave the appearance that the Activity loader had hung.