Develop Reference

startActivity() silently fails if called from the background after you press the home button

If you press the home button on an Android device and then you call startActivity() it will silently fail and there doesn't seem to be a way to check when it fails. For example:
#Override
protected void onStop() {
super.onStop();
Handler hndlr = new Handler();
Runnable t = new Runnable() {
public void run() {
startActivity(new Intent(getApplicationContext(), SomeOtherActivity.class)); //this silently fails, no error, nothing
}
};
hndlr.postDelayed(t, 1000);
}
Is there a way to check if it fails to start the activity? I don't intend to start any activity in the background, I just need to know when it fails. Please note that this only happens when you press the home button, I'm actually not sure if this is just an Android bug (I'm testing on Android 11). Thanks!

You could just check that your app is in the foreground like this:
if (getLifecycle().getCurrentState().isAtLeast(Lifecycle.State.RESUMED)){
startActivity(new Intent(getApplicationContext(), SomeOtherActivity.class));
}

Is there a way to exactly detect when an activity is destroyed in android?

I am making an android app in java in which I need to trigger some database requests whenever an activity is completely destroyed which would probably happen if the user presses the back button or leaves the app itself... But the onDestroy() function in my app is randomly getting triggered even when the user is still on the activity... I guess the probable reason for this is configuration changes but I am not able to figure out a proper solution for this.
Is there a way we could exactly detect when an activity is left by a user avoiding any in-page configuration changes??
The onDestroy() that I am using is this:
#Override
protected void onDestroy() {
/// do smthng
super.onDestroy();
}
Any help would be appreciated!!

Solved:
Thank you for the answer guys... For me onStop() worked out perfectly and it is working in every case whether it might be pressing the back button or exiting the activity or the app itself!!

If you want to check if the user ended the activity, meaning pressed back, do this:
#override
public void onBackPressed(){
//do something before we finish the activity
super.onBackPressed();
}
If you want to check when user, goes to next activity, then resturns to the same activity:
#override
public void onResume(){
//do something when return back to this activity
super.onResume();
}
#override
public void onPause(){
//do something before going to another activity
super.onPause();
}
onDestroy is called when the activity is destroyed or finished and not guaranteed to be called always, don't depend on it

We can check on whether our application is foreground or background based on the activity entering and exiting the foreground by implementing ActivityLifecycleCallbacks.
Good reference : https://medium.com/#iamsadesh/android-how-to-detect-when-app-goes-background-foreground-fd5a4d331f8a
Quoting from the above article,
#Override
public void onActivityStarted(Activity activity) {
if (++activityReferences == 1 && !isActivityChangingConfigurations) {
// App enters foreground
}
}
and,
#Override
public void onActivityStopped(Activity activity) {
isActivityChangingConfigurations = activity.isChangingConfigurations();
if (--activityReferences == 0 && !isActivityChangingConfigurations) {
// App enters background
}
}
by which we can make sure that our app is in foreground or not. Here you always have the control of what activity is in foreground based on which you can check and execute the logic.

Have to press the back button twice to get to previous activity?

I am simply trying to click back and navigate to my previous activity. My flow is this: I go to news_feed activity -> Comments activity -> User Profile activity -> click back (Go to Comments activity) -> click back (This does nothing for some reason) -> Click back (Go back to news_feed activity). I'm not sure why I have to click back twice when I try to go from Comments activity back to news_feed activity. If I go from news_feed activity -> Comments -> press back (Go to news_feed activity) this works perfectly. Here is my code:
news_feed.java:
#Override
public void onBackPressed() {
super.onBackPressed();
Intent startMain = new Intent(Intent.ACTION_MAIN);
startMain.addCategory(Intent.CATEGORY_HOME);
startMain.setFlags(Intent.FLAG_ACTIVITY_NEW_TASK);
startActivity(startMain);
}
Comments.java:
#Override
public void onBackPressed() {
super.onBackPressed();
this.finish();
}
UserProfile.java:
#Override
public void onBackPressed() {
super.onBackPressed();
Intent intent = new Intent(UserProfile.this, Comments.class);
Bundle bundle = new Bundle();
bundle.putString("postId", postId);
bundle.putString("posterUserId", posterUserId);
bundle.putString("posterName", posterName);
bundle.putString("postStatus", postStatus);
bundle.putString("postTimeStamp", postTimeStamp);
bundle.putString("postTitle", postTitle);
intent.putExtras(bundle);
startActivity(intent);
finish();
}
I don't think navigating to these activities would change anything, but I can include the intents that I used to navigate to these activities also if necessary. Otherwise I just included the onBackPressed code that I had for these activities. Any ideas why this might cause a problem? Any help would be appreciated. Thanks.

In your UserProfile class, in onBackPressed() method, you are starting the Comments class again. Why do you have to do this?
What is happening is, you are starting a new Comments activity onBackPressed() of the USerProfile class, so there are two instances of Comments Activity. So you feel you are pressing back btn twice.
If you have to pass data back to Comments from UserProfile class, then make use of setResult() method.
This will be of help
How to pass data from 2nd activity to 1st activity when pressed back? - android
Sending data back to the Main Activity in android

I you want to send back the result to previous activity the start activity by using
startActivityForResult()
insead of
startActivity()
and don't override
onBackPressed()

You can try something like this:
private boolean clicked;
#Override
public void onBackPressed() {
if (!clicked) { // if it was not clicked before, change the value of clicked to true and do nothing directly return, if clicked again, then it will be finish the activity.
clicked=true;
return;
}
super.onBackPressed();
}
And if you are going to use the time, then you can do like this:
private long lastClicked;
#Override
public void onBackPressed() {
if (System.currentTimeMillis() - lastClicked < 1000) { // within one second
super.onBackPressed();
}
lastClicked = System.currentTimeMillis();
}

You don't need to override onBackPressed() if all you're going to do is call startActivity() and finish() in the current activity. The Android backstack will handle both of those for you. Moreover, in your UserProfile.java you are passing data to previous activity. For this, you should use startActvityForResult() in the Comments activity (i.e the previous activity) instead of startActivity().
To learn more about startActvityForResult() visit: https://developer.android.com/training/basics/intents/result.html

public void onBackPressed() {
if (this.lastBackPressTime < System.currentTimeMillis() - 2000) {
this.lastBackPressTime = System.currentTimeMillis();
} else {
//super.onBackPressed(); for exit
//INTENT HERE TO YOUR SECOND ACTIVITY like below
Intent intent=new Intent(A.this,B.class);
startActivirty(intent);
}
}
Create a global variable
private long lastBackPressTime = 0;
Hope this will help you,Let me know..

Make android activity close itelf

I have a function time() in my openGLActivity class. The openGLActivity is open by my Main activtiy. I've tried calling super.onPause() then super.onStop(); and i just get errors. This time function is called inside of my GLrenderer class. Can an activity cloe itself after a time limit?
timer(){
t+=1;
if(t==1000){
finish();
}
}

If I didn't misunderstand your question, you can easily do that with handler. This should close the activity. Use it onCreate()
new Handler().postDelayed(new Runnable() {
#Override
public void run() {
OpenGLActivity.this.finish();
}
}, 3000);

Activities in the system are managed as an activity stack. It means that if Activity1 calls Acitivity2 by
startActivity(Intent i)
Activity2 remains alive until you go back since the Activity1.

Override back button to act like home button

On pressing the back button, I'd like my application to go into the stopped state, rather than the destroyed state.
In the Android docs it states:
...not all activities have the behavior that they are destroyed when BACK is pressed. When the user starts playing music in the Music application and then presses BACK, the application overrides the normal back behavior, preventing the player activity from being destroyed, and continues playing music, even though its activity is no longer visible
How do I replicate this functionality in my own application?
I think there must be three possibilities...
Capture the back button press (as below) and then call whatever method(s) the home button calls.
#Override
public boolean onKeyDown(int keyCode, KeyEvent event) {
if ((keyCode == KeyEvent.KEYCODE_BACK)) {
Log.d(this.getClass().getName(), "back button pressed");
}
return super.onKeyDown(keyCode, event);
}
Capture the back button press and then spoof a home button press.
Capture the back button press, then start an Activity of the home screen, effectively putting my application's Activity into the stopped state.
Edit:
I know about services and am using one in the application to which this problem is related. This question is specifically about putting the Activity into the stopped state rather than the destroyed state on pressing the back button.

Most of the time you need to create a Service to perform something in the background, and your visible Activity simply controls this Service. (I'm sure the Music player works in the same way, so the example in the docs seems a bit misleading.) If that's the case, then your Activity can finish as usual and the Service will still be running.
A simpler approach is to capture the Back button press and call moveTaskToBack(true) as follows:
// 2.0 and above
#Override
public void onBackPressed() {
moveTaskToBack(true);
}
// Before 2.0
#Override
public boolean onKeyDown(int keyCode, KeyEvent event) {
if (keyCode == KeyEvent.KEYCODE_BACK) {
moveTaskToBack(true);
return true;
}
return super.onKeyDown(keyCode, event);
}
I think the preferred option should be for an Activity to finish normally and be able to recreate itself e.g. reading the current state from a Service if needed. But moveTaskToBack can be used as a quick alternative on occasion.
NOTE: as pointed out by Dave below Android 2.0 introduced a new onBackPressed method, and these recommendations on how to handle the Back button.

Use the following code:
public void onBackPressed() {
Intent intent = new Intent();
intent.setAction(Intent.ACTION_MAIN);
intent.addCategory(Intent.CATEGORY_HOME);
startActivity(intent);
}

If you want to catch the Back Button have a look at this post on the Android Developer Blog. It covers the easier way to do this in Android 2.0 and the best way to do this for an application that runs on 1.x and 2.0.
However, if your Activity is Stopped it still may be killed depending on memory availability on the device. If you want a process to run with no UI you should create a Service. The documentation says the following about Services:
A service doesn't have a visual user interface, but rather runs in the background for an indefinite period of time. For example, a service might play background music as the user attends to other matters, or it might fetch data over the network or calculate something and provide the result to activities that need it.
These seems appropriate for your requirements.

try to override void onBackPressed() defined in android.app.Activity class.

if it helps someone else, I had an activity with 2 layouts that I toggled on and off for visibilty, trying to emulate a kind of page1 > page2 structure. if they were on page 2 and pressed the back button I wanted them to go back to page 1, if they pressed the back button on page 1 it should still work as normal. Its pretty basic but it works
#Override
public void onBackPressed() {
// check if page 2 is open
RelativeLayout page2layout = (RelativeLayout)findViewById(R.id.page2layout);
if(page2layout.getVisibility() == View.VISIBLE){
togglePageLayout(); // my method to toggle the views
return;
}else{
super.onBackPressed(); // allows standard use of backbutton for page 1
}
}
hope it helps someone,
cheers

Working example..
Make sure don't call super.onBackPressed();
#Override
public void onBackPressed() {
Log.d("CDA", "onBackPressed Called");
Intent setIntent = new Intent(Intent.ACTION_MAIN);
setIntent.addCategory(Intent.CATEGORY_HOME);
setIntent.setFlags(Intent.FLAG_ACTIVITY_NEW_TASK);
startActivity(setIntent);
}
In this way your Back Button act like Home button . It doesn't finishes your activity but take it to background
Second way is to call moveTaskToBack(true); in onBackPressed and be sure to remove super.onBackPressed

Even better, how about OnPause():
Called as part of the activity lifecycle when an activity is going into the background, but has not (yet) been killed. The counterpart to onResume().
When activity B is launched in front of activity A, this callback will be invoked on A. B will not be created until A's onPause() returns, so be sure toenter code here not do anything lengthy here.
This callback is mostly used for saving any persistent state the activity is editing and making sure nothing is lost if there are not enough resources to start the new activity without first killing this one.
This is also a good place to do things like stop animations and other things that consume a noticeable amount of CPU in order to make the switch to the next activity as fast as possible, or to close resources that are exclusive access such as the camera.

Override onBackPressed() after android 2.0.
Such as
#Override
public void onBackPressed() {
moveTaskToBack(true);
}

I have use #Mirko N. answser using made the new Custom EditText
public class EditViewCustom extends EditText {
Button cancelBtn;
RelativeLayout titleReleLayout;
public EditViewCustom(Context context, AttributeSet attrs, int defStyle) {
super(context, attrs, defStyle);
}
public EditViewCustom(Context context, AttributeSet attrs) {
super(context, attrs);
}
public EditViewCustom(Context context) {
super(context);
}
public void setViews(Button cancelBtn,RelativeLayout titleReleLayout){
this.cancelBtn = cancelBtn;
this.titleReleLayout = titleReleLayout;
}
#Override
public boolean onKeyPreIme(int keyCode, KeyEvent event) {
if (event.getKeyCode() == KeyEvent.KEYCODE_BACK) {
Log.d("KEYCODE_BACK","KEYCODE_BACK");
cancelBtn.setVisibility(View.GONE);
this.setFocusableInTouchMode(false);
this.setFocusable(false);
titleReleLayout.setVisibility(View.VISIBLE);
return super.onKeyPreIme(keyCode, event);
}
return super.onKeyPreIme(keyCode, event);
}
}
Then set data from your activity
searchEditView.setViews(cancelBtn, titleRelativeLayout);
Thank you.

I've tried all the above solutions, but none of them worked for me. The following code helped me, when trying to return to MainActivity in a way that onCreate gets called:
Intent.FLAG_ACTIVITY_CLEAR_TOP is the key.
#Override
public void onBackPressed() {
Intent intent = new Intent(this, MainActivity.class);
intent.setFlags(Intent.FLAG_ACTIVITY_NEW_TASK | Intent.FLAG_ACTIVITY_CLEAR_TOP);
startActivity(intent);
}