In my Android application, when I rotate the device (slide out the keyboard) then my Activity is restarted (onCreate is called). Now, this is probably how it's supposed to be, but I do a lot of initial setting up in the onCreate method, so I need either:
onCreate is not called again and the layout just adjusts oronCreate is not called.This question is related to
android
rotation
android-activity
There are multiple ways to do this:
Handle orientation changes by yourself
Another alternative is to handle the orientation changes by yourself. But this is not considered a good practice.
Add this to your manifest file.
android:configChanges="keyboardHidden|orientation"
for Android 3.2 and later:
android:configChanges="keyboardHidden|orientation|screenSize"
@Override
public void onConfigurationChanged(Configuration config) {
super.onConfigurationChanged(config);
if (newConfig.orientation == Configuration.ORIENTATION_PORTRAIT) {
//Handle rotation from landscape to portarit mode here
} else if (newConfig.orientation == Configuration.ORIENTATION_LANDSCAPE){
//Handle rotation from portrait to landscape mode here
}
}
OR Restrict rotation
You can also confine your activity to portrait or landscape mode to avoid rotation.
Add this to the activity tag in your manifest file:
android:screenOrientation="portrait"
Or implement this programmatically in your activity:
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setRequestedOrientation(ActivityInfo.SCREEN_ORIENTATION_PORTRAIT);
}
OR Save Activity State
You can save the activity state in onSaveInstanceState.
@Override
public void onSaveInstanceState(Bundle outState) {
/*Save your data to be restored here
Example : outState.putLong("time_state", time); , time is a long variable*/
super.onSaveInstanceState(outState);
}
and then use the bundle to restore the state.
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
if(savedInstanceState!= null){
/*When rotation occurs
Example : time = savedInstanceState.getLong("time_state", 0); */
} else {
//When onCreate is called for the first time
}
}
Add this line to your manifest :-
android:configChanges="orientation|keyboard|keyboardHidden|screenSize|screenLayout|uiMode"
and this snippet to the activity :-
@Override
public void onConfigurationChanged(Configuration newConfig) {
super.onConfigurationChanged(newConfig);
getWindow().setFlags(WindowManager.LayoutParams.FLAG_FULLSCREEN,
WindowManager.LayoutParams.FLAG_FULLSCREEN);
}
You might also consider using the Android platform's way of persisting data across orientation changes: onRetainNonConfigurationInstance() and getLastNonConfigurationInstance().
This allows you to persist data across configuration changes, such as information you may have gotten from a server fetch or something else that's been computed in onCreate or since, while also allowing Android to re-layout your Activity using the xml file for the orientation now in use.
It should be noted that these methods are now deprecated (although still more flexible than handling orientation change yourself as most of the above solutions suggest) with the recommendation that everyone switch to Fragments and instead use setRetainInstance(true) on each Fragment you want to retain.
Update for Android 3.2 and higher:
Caution: Beginning with Android 3.2 (API level 13), the "screen size" also changes when the device switches between portrait and landscape orientation. Thus, if you want to prevent runtime restarts due to orientation change when developing for API level 13 or higher (as declared by the minSdkVersion and targetSdkVersion attributes), you must include the
"screenSize"value in addition to the"orientation"value. That is, you must declareandroid:configChanges="orientation|screenSize". However, if your application targets API level 12 or lower, then your activity always handles this configuration change itself (this configuration change does not restart your activity, even when running on an Android 3.2 or higher device).
Note: I post this answer if someone in the future face the same problem as me. For me the following line wasn't enought:
android:configChanges="orientation"
When I rotated the screen, the method `onConfigurationChanged(Configuration newConfig) did't get called.
Solution: I also had to add "screenSize" even if the problem had to do with the orientation. So in the AndroidManifest.xml - file, add this:
android:configChanges="keyboardHidden|orientation|screenSize"
Then implement the method onConfigurationChanged(Configuration newConfig)
Every time when screen is rotated, opened activity is finished and onCreate() is called again.
1 . You can do one thing save the state of activity when screen is rotated so that, You can recover all old stuff when activity's onCreate() is called again. Refer this link
2 . If you want to prevent restarting of the activity just place following lines in your manifest.xml file.
<activity android:name=".Youractivity"
android:configChanges="orientation|screenSize"/>
The onCreate method is still called even when you change the orientation of android. So moving all the heavy functionality to this method is not going to help you
I just discovered this lore:
For keeping the Activity alive through an orientation change, and handling it through onConfigurationChanged, the documentation and the code sample above suggest this in the Manifest file:
<activity android:name=".MyActivity"
android:configChanges="orientation|keyboardHidden"
android:label="@string/app_name">
which has the extra benefit that it always works.
The bonus lore is that omitting the keyboardHidden may seem logical, but it causes failures in the emulator (for Android 2.1 at least): specifying only orientation will make the emulator call both OnCreate and onConfigurationChanged sometimes, and only OnCreate other times.
I haven't seen the failure on a device, but I have heard about the emulator failing for others. So it's worth documenting.
After a while of trial and error, I found a solution which fits my needs in the most situations. Here is the Code:
Manifest configuration:
<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="com.pepperonas.myapplication">
<application
android:name=".App"
android:allowBackup="true"
android:icon="@mipmap/ic_launcher"
android:label="@string/app_name"
android:supportsRtl="true"
android:theme="@style/AppTheme">
<activity
android:name=".MainActivity"
android:configChanges="orientation|keyboardHidden|screenSize">
<intent-filter>
<action android:name="android.intent.action.MAIN"/>
<category android:name="android.intent.category.LAUNCHER"/>
</intent-filter>
</activity>
</application>
</manifest>
MainActivity:
import android.content.res.Configuration;
import android.os.Bundle;
import android.support.v4.app.Fragment;
import android.support.v4.app.FragmentManager;
import android.support.v4.app.FragmentTransaction;
import android.support.v7.app.AppCompatActivity;
import android.util.Log;
import android.view.View;
import android.widget.Button;
public class MainActivity extends AppCompatActivity implements View.OnClickListener {
private static final String TAG = "MainActivity";
private Fragment mFragment;
private int mSelected = -1;
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
Log.d(TAG, "onCreate " + "");
// null check not realy needed - but just in case...
if (savedInstanceState == null) {
initUi();
// get an instance of FragmentTransaction from your Activity
FragmentManager fragmentManager = getSupportFragmentManager();
FragmentTransaction fragmentTransaction = fragmentManager.beginTransaction();
/*IMPORTANT: Do the INITIAL(!) transaction only once!
* If we call this everytime the layout changes orientation,
* we will end with a messy, half-working UI.
* */
mFragment = FragmentOne.newInstance(mSelected = 0);
fragmentTransaction.add(R.id.frame, mFragment);
fragmentTransaction.commit();
}
}
@Override
public void onConfigurationChanged(Configuration newConfig) {
super.onConfigurationChanged(newConfig);
Log.d(TAG, "onConfigurationChanged " +
(newConfig.orientation
== Configuration.ORIENTATION_LANDSCAPE
? "landscape" : "portrait"));
initUi();
Log.i(TAG, "onConfigurationChanged - last selected: " + mSelected);
makeFragmentTransaction(mSelected);
}
/**
* Called from {@link #onCreate} and {@link #onConfigurationChanged}
*/
private void initUi() {
setContentView(R.layout.activity_main);
Log.d(TAG, "onCreate instanceState == null / reinitializing..." + "");
Button btnFragmentOne = (Button) findViewById(R.id.btn_fragment_one);
Button btnFragmentTwo = (Button) findViewById(R.id.btn_fragment_two);
btnFragmentOne.setOnClickListener(this);
btnFragmentTwo.setOnClickListener(this);
}
/**
* Not invoked (just for testing)...
*/
@Override
protected void onSaveInstanceState(Bundle outState) {
super.onSaveInstanceState(outState);
Log.d(TAG, "onSaveInstanceState " + "YOU WON'T SEE ME!!!");
}
/**
* Not invoked (just for testing)...
*/
@Override
protected void onRestoreInstanceState(Bundle savedInstanceState) {
super.onRestoreInstanceState(savedInstanceState);
Log.d(TAG, "onSaveInstanceState " + "YOU WON'T SEE ME, AS WELL!!!");
}
@Override
protected void onResume() {
super.onResume();
Log.d(TAG, "onResume " + "");
}
@Override
protected void onPause() {
super.onPause();
Log.d(TAG, "onPause " + "");
}
@Override
protected void onDestroy() {
super.onDestroy();
Log.d(TAG, "onDestroy " + "");
}
@Override
public void onClick(View v) {
switch (v.getId()) {
case R.id.btn_fragment_one:
Log.d(TAG, "onClick btn_fragment_one " + "");
makeFragmentTransaction(0);
break;
case R.id.btn_fragment_two:
Log.d(TAG, "onClick btn_fragment_two " + "");
makeFragmentTransaction(1);
break;
default:
Log.d(TAG, "onClick null - wtf?!" + "");
}
}
/**
* We replace the current Fragment with the selected one.
* Note: It's called from {@link #onConfigurationChanged} as well.
*/
private void makeFragmentTransaction(int selection) {
switch (selection) {
case 0:
mFragment = FragmentOne.newInstance(mSelected = 0);
break;
case 1:
mFragment = FragmentTwo.newInstance(mSelected = 1);
break;
}
// Create new transaction
FragmentTransaction transaction = getSupportFragmentManager().beginTransaction();
// Replace whatever is in the fragment_container view with this fragment,
// and add the transaction to the back stack
transaction.replace(R.id.frame, mFragment);
/*This would add the Fragment to the backstack...
* But right now we comment it out.*/
// transaction.addToBackStack(null);
// Commit the transaction
transaction.commit();
}
}
And sample Fragment:
import android.os.Bundle;
import android.support.v4.app.Fragment;
import android.util.Log;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
/**
* @author Martin Pfeffer (pepperonas)
*/
public class FragmentOne extends Fragment {
private static final String TAG = "FragmentOne";
public static Fragment newInstance(int i) {
Fragment fragment = new FragmentOne();
Bundle args = new Bundle();
args.putInt("the_id", i);
fragment.setArguments(args);
return fragment;
}
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
Log.d(TAG, "onCreateView " + "");
return inflater.inflate(R.layout.fragment_one, container, false);
}
}
Can be found on github.
The way I have found to do this is use the onRestoreInstanceState and the onSaveInstanceState events to save something in the Bundle (even if you dont need any variables saved, just put something in there so the Bundle isn't empty). Then, on the onCreate method, check to see if the Bundle is empty, and if it is, then do the initialization, if not, then do it.
There are several ways to do this:
You can save the activity state in onSaveInstanceState.
@Override
public void onSaveInstanceState(Bundle outState) {
/*Save your data to be restored here
Example : outState.putLong("time_state", time); , time is a long variable*/
super.onSaveInstanceState(outState);
}
and then use the bundle to restore the state.
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
if(savedInstanceState!= null){
/*When rotation occurs
Example : time = savedInstanceState.getLong("time_state", 0); */
} else {
//When onCreate is called for the first time
}
}
Another alternative is to handle the orientation changes by yourself. But this is not considered a good practice.
Add this to your manifest file.
android:configChanges="keyboardHidden|orientation"
for Android 3.2 and later:
android:configChanges="keyboardHidden|orientation|screenSize"
@Override
public void onConfigurationChanged(Configuration config) {
super.onConfigurationChanged(config);
if (newConfig.orientation == Configuration.ORIENTATION_PORTRAIT) {
//Handle rotation from landscape to portarit mode here
} else if (newConfig.orientation == Configuration.ORIENTATION_LANDSCAPE){
//Handle rotation from portrait to landscape mode here
}
}
You can also confine your activity to portrait or landscape mode to avoid rotation.
Add this to the activity tag in your manifest file:
android:screenOrientation="portrait"
Or implement this programmatically in your activity:
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setRequestedOrientation(ActivityInfo.SCREEN_ORIENTATION_PORTRAIT);
}
What you describe is the default behavior. You have to detect and handle these events yourself by adding:
android:configChanges
to your manifest and then the changes that you want to handle. So for orientation, you would use:
android:configChanges="orientation"
and for the keyboard being opened or closed you would use:
android:configChanges="keyboardHidden"
If you want to handle both you can just separate them with the pipe command like:
android:configChanges="keyboardHidden|orientation"
This will trigger the onConfigurationChanged method in whatever Activity you call. If you override the method you can pass in the new values.
Hope this helps.
what I did...
in the manifest, to the activity section, added:
android:configChanges="keyboardHidden|orientation"
in the code for the activity, implemented:
//used in onCreate() and onConfigurationChanged() to set up the UI elements
public void InitializeUI()
{
//get views from ID's
this.textViewHeaderMainMessage = (TextView) this.findViewById(R.id.TextViewHeaderMainMessage);
//etc... hook up click listeners, whatever you need from the Views
}
//Called when the activity is first created.
@Override
public void onCreate(Bundle savedInstanceState)
{
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
InitializeUI();
}
//this is called when the screen rotates.
// (onCreate is no longer called when screen rotates due to manifest, see: android:configChanges)
@Override
public void onConfigurationChanged(Configuration newConfig)
{
super.onConfigurationChanged(newConfig);
setContentView(R.layout.main);
InitializeUI();
}
Instead of trying to stop the onCreate() from being fired altogether, maybe try checking the Bundle savedInstanceState being passed into the event to see if it is null or not.
For instance, if I have some logic that should be run when the Activity is truly created, not on every orientation change, I only run that logic in the onCreate() only if the savedInstanceState is null.
Otherwise, I still want the layout to redraw properly for the orientation.
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_game_list);
if(savedInstanceState == null){
setupCloudMessaging();
}
}
not sure if this is the ultimate answer, but it works for me.
Put the code below inside your <activity> tag in Manifest.xml:
android:configChanges="screenLayout|screenSize|orientation"
you need to use the onSavedInstanceState method to store all the value to its parameter is has that is bundle
@Override
public void onSaveInstanceState(Bundle outState, PersistableBundle outPersistentState) {
super.onSaveInstanceState(outState, outPersistentState);
outPersistentState.putBoolean("key",value);
}
and use
@Override
protected void onRestoreInstanceState(Bundle savedInstanceState) {
super.onRestoreInstanceState(savedInstanceState);
savedInstanceState.getBoolean("key");
}
to retrive and set the value to view objects it will handles the screen rotations
Put this below code in your Activity in Android Manifest.
android:configChanges="orientation"
This will not restart your activity when you would change orientation.
After a while of trial and error, I found a solution which fits my needs in the most situations. Here is the Code:
Manifest configuration:
<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="com.pepperonas.myapplication">
<application
android:name=".App"
android:allowBackup="true"
android:icon="@mipmap/ic_launcher"
android:label="@string/app_name"
android:supportsRtl="true"
android:theme="@style/AppTheme">
<activity
android:name=".MainActivity"
android:configChanges="orientation|keyboardHidden|screenSize">
<intent-filter>
<action android:name="android.intent.action.MAIN"/>
<category android:name="android.intent.category.LAUNCHER"/>
</intent-filter>
</activity>
</application>
</manifest>
MainActivity:
import android.content.res.Configuration;
import android.os.Bundle;
import android.support.v4.app.Fragment;
import android.support.v4.app.FragmentManager;
import android.support.v4.app.FragmentTransaction;
import android.support.v7.app.AppCompatActivity;
import android.util.Log;
import android.view.View;
import android.widget.Button;
public class MainActivity extends AppCompatActivity implements View.OnClickListener {
private static final String TAG = "MainActivity";
private Fragment mFragment;
private int mSelected = -1;
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
Log.d(TAG, "onCreate " + "");
// null check not realy needed - but just in case...
if (savedInstanceState == null) {
initUi();
// get an instance of FragmentTransaction from your Activity
FragmentManager fragmentManager = getSupportFragmentManager();
FragmentTransaction fragmentTransaction = fragmentManager.beginTransaction();
/*IMPORTANT: Do the INITIAL(!) transaction only once!
* If we call this everytime the layout changes orientation,
* we will end with a messy, half-working UI.
* */
mFragment = FragmentOne.newInstance(mSelected = 0);
fragmentTransaction.add(R.id.frame, mFragment);
fragmentTransaction.commit();
}
}
@Override
public void onConfigurationChanged(Configuration newConfig) {
super.onConfigurationChanged(newConfig);
Log.d(TAG, "onConfigurationChanged " +
(newConfig.orientation
== Configuration.ORIENTATION_LANDSCAPE
? "landscape" : "portrait"));
initUi();
Log.i(TAG, "onConfigurationChanged - last selected: " + mSelected);
makeFragmentTransaction(mSelected);
}
/**
* Called from {@link #onCreate} and {@link #onConfigurationChanged}
*/
private void initUi() {
setContentView(R.layout.activity_main);
Log.d(TAG, "onCreate instanceState == null / reinitializing..." + "");
Button btnFragmentOne = (Button) findViewById(R.id.btn_fragment_one);
Button btnFragmentTwo = (Button) findViewById(R.id.btn_fragment_two);
btnFragmentOne.setOnClickListener(this);
btnFragmentTwo.setOnClickListener(this);
}
/**
* Not invoked (just for testing)...
*/
@Override
protected void onSaveInstanceState(Bundle outState) {
super.onSaveInstanceState(outState);
Log.d(TAG, "onSaveInstanceState " + "YOU WON'T SEE ME!!!");
}
/**
* Not invoked (just for testing)...
*/
@Override
protected void onRestoreInstanceState(Bundle savedInstanceState) {
super.onRestoreInstanceState(savedInstanceState);
Log.d(TAG, "onSaveInstanceState " + "YOU WON'T SEE ME, AS WELL!!!");
}
@Override
protected void onResume() {
super.onResume();
Log.d(TAG, "onResume " + "");
}
@Override
protected void onPause() {
super.onPause();
Log.d(TAG, "onPause " + "");
}
@Override
protected void onDestroy() {
super.onDestroy();
Log.d(TAG, "onDestroy " + "");
}
@Override
public void onClick(View v) {
switch (v.getId()) {
case R.id.btn_fragment_one:
Log.d(TAG, "onClick btn_fragment_one " + "");
makeFragmentTransaction(0);
break;
case R.id.btn_fragment_two:
Log.d(TAG, "onClick btn_fragment_two " + "");
makeFragmentTransaction(1);
break;
default:
Log.d(TAG, "onClick null - wtf?!" + "");
}
}
/**
* We replace the current Fragment with the selected one.
* Note: It's called from {@link #onConfigurationChanged} as well.
*/
private void makeFragmentTransaction(int selection) {
switch (selection) {
case 0:
mFragment = FragmentOne.newInstance(mSelected = 0);
break;
case 1:
mFragment = FragmentTwo.newInstance(mSelected = 1);
break;
}
// Create new transaction
FragmentTransaction transaction = getSupportFragmentManager().beginTransaction();
// Replace whatever is in the fragment_container view with this fragment,
// and add the transaction to the back stack
transaction.replace(R.id.frame, mFragment);
/*This would add the Fragment to the backstack...
* But right now we comment it out.*/
// transaction.addToBackStack(null);
// Commit the transaction
transaction.commit();
}
}
And sample Fragment:
import android.os.Bundle;
import android.support.v4.app.Fragment;
import android.util.Log;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
/**
* @author Martin Pfeffer (pepperonas)
*/
public class FragmentOne extends Fragment {
private static final String TAG = "FragmentOne";
public static Fragment newInstance(int i) {
Fragment fragment = new FragmentOne();
Bundle args = new Bundle();
args.putInt("the_id", i);
fragment.setArguments(args);
return fragment;
}
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
Log.d(TAG, "onCreateView " + "");
return inflater.inflate(R.layout.fragment_one, container, false);
}
}
Can be found on github.
There are several ways to do this:
You can save the activity state in onSaveInstanceState.
@Override
public void onSaveInstanceState(Bundle outState) {
/*Save your data to be restored here
Example : outState.putLong("time_state", time); , time is a long variable*/
super.onSaveInstanceState(outState);
}
and then use the bundle to restore the state.
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
if(savedInstanceState!= null){
/*When rotation occurs
Example : time = savedInstanceState.getLong("time_state", 0); */
} else {
//When onCreate is called for the first time
}
}
Another alternative is to handle the orientation changes by yourself. But this is not considered a good practice.
Add this to your manifest file.
android:configChanges="keyboardHidden|orientation"
for Android 3.2 and later:
android:configChanges="keyboardHidden|orientation|screenSize"
@Override
public void onConfigurationChanged(Configuration config) {
super.onConfigurationChanged(config);
if (newConfig.orientation == Configuration.ORIENTATION_PORTRAIT) {
//Handle rotation from landscape to portarit mode here
} else if (newConfig.orientation == Configuration.ORIENTATION_LANDSCAPE){
//Handle rotation from portrait to landscape mode here
}
}
You can also confine your activity to portrait or landscape mode to avoid rotation.
Add this to the activity tag in your manifest file:
android:screenOrientation="portrait"
Or implement this programmatically in your activity:
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setRequestedOrientation(ActivityInfo.SCREEN_ORIENTATION_PORTRAIT);
}
you need to use the onSavedInstanceState method to store all the value to its parameter is has that is bundle
@Override
public void onSaveInstanceState(Bundle outState, PersistableBundle outPersistentState) {
super.onSaveInstanceState(outState, outPersistentState);
outPersistentState.putBoolean("key",value);
}
and use
@Override
protected void onRestoreInstanceState(Bundle savedInstanceState) {
super.onRestoreInstanceState(savedInstanceState);
savedInstanceState.getBoolean("key");
}
to retrive and set the value to view objects it will handles the screen rotations
The onCreate method is still called even when you change the orientation of android. So moving all the heavy functionality to this method is not going to help you
Instead of trying to stop the onCreate() from being fired altogether, maybe try checking the Bundle savedInstanceState being passed into the event to see if it is null or not.
For instance, if I have some logic that should be run when the Activity is truly created, not on every orientation change, I only run that logic in the onCreate() only if the savedInstanceState is null.
Otherwise, I still want the layout to redraw properly for the orientation.
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_game_list);
if(savedInstanceState == null){
setupCloudMessaging();
}
}
not sure if this is the ultimate answer, but it works for me.
You may use ViewModel object in your activity.
ViewModel objects are automatically retained during configuration changes so that data they hold is immediately available to the next activity or fragment instance. Read more:
https://developer.android.com/topic/libraries/architecture/viewmodel
Changes to be made in the Android manifest are:
android:configChanges="keyboardHidden|orientation"
Additions to be made inside activity are:
public void onConfigurationChanged(Configuration newConfig) {
super.onConfigurationChanged(newConfig);
// Checks the orientation of the screen
if (newConfig.orientation == Configuration.ORIENTATION_LANDSCAPE) {
Toast.makeText(this, "landscape", Toast.LENGTH_SHORT).show();
} else if (newConfig.orientation == Configuration.ORIENTATION_PORTRAIT) {
Toast.makeText(this, "portrait", Toast.LENGTH_SHORT).show();
}
}
In the activity section of the manifest, add:
android:configChanges="keyboardHidden|orientation"
People are saying that you should use
android:configChanges="keyboardHidden|orientation"
But the best and most professional way to handle rotation in Android is to use the Loader class. It's not a famous class(I don't know why), but it is way better than the AsyncTask. For more information, you can read the Android tutorials found in Udacity's Android courses.
Of course, as another way, you could store the values or the views with onSaveInstanceState and read them with onRestoreInstanceState. It's up to you really.
What you describe is the default behavior. You have to detect and handle these events yourself by adding:
android:configChanges
to your manifest and then the changes that you want to handle. So for orientation, you would use:
android:configChanges="orientation"
and for the keyboard being opened or closed you would use:
android:configChanges="keyboardHidden"
If you want to handle both you can just separate them with the pipe command like:
android:configChanges="keyboardHidden|orientation"
This will trigger the onConfigurationChanged method in whatever Activity you call. If you override the method you can pass in the new values.
Hope this helps.
In the activity section of the manifest, add:
android:configChanges="keyboardHidden|orientation"
I just discovered this lore:
For keeping the Activity alive through an orientation change, and handling it through onConfigurationChanged, the documentation and the code sample above suggest this in the Manifest file:
<activity android:name=".MyActivity"
android:configChanges="orientation|keyboardHidden"
android:label="@string/app_name">
which has the extra benefit that it always works.
The bonus lore is that omitting the keyboardHidden may seem logical, but it causes failures in the emulator (for Android 2.1 at least): specifying only orientation will make the emulator call both OnCreate and onConfigurationChanged sometimes, and only OnCreate other times.
I haven't seen the failure on a device, but I have heard about the emulator failing for others. So it's worth documenting.
The way I have found to do this is use the onRestoreInstanceState and the onSaveInstanceState events to save something in the Bundle (even if you dont need any variables saved, just put something in there so the Bundle isn't empty). Then, on the onCreate method, check to see if the Bundle is empty, and if it is, then do the initialization, if not, then do it.
Fix the screen orientation (landscape or portrait) in AndroidManifest.xml
android:screenOrientation="portrait" or android:screenOrientation="landscape"
for this your onResume() method is not called.
The approach is useful but is incomplete when using Fragments.
Fragments usually get recreated on configuration change. If you don't wish this to happen, use
setRetainInstance(true); in the Fragment's constructor(s)
This will cause fragments to be retained during configuration change.
http://developer.android.com/reference/android/app/Fragment.html#setRetainInstance(boolean)
Add this line in manifest : android:configChanges="orientation|screenSize"
Note: I post this answer if someone in the future face the same problem as me. For me the following line wasn't enought:
android:configChanges="orientation"
When I rotated the screen, the method `onConfigurationChanged(Configuration newConfig) did't get called.
Solution: I also had to add "screenSize" even if the problem had to do with the orientation. So in the AndroidManifest.xml - file, add this:
android:configChanges="keyboardHidden|orientation|screenSize"
Then implement the method onConfigurationChanged(Configuration newConfig)
It is very simple just do the following steps:
<activity
android:name=".Test"
android:configChanges="orientation|screenSize"
android:screenOrientation="landscape" >
</activity>
This works for me :
Note: orientation depends on your requitement
Use orientation listener to perform different tasks on different orientation.
@Override
public void onConfigurationChanged(Configuration myConfig)
{
super.onConfigurationChanged(myConfig);
int orient = getResources().getConfiguration().orientation;
switch(orient)
{
case Configuration.ORIENTATION_LANDSCAPE:
setRequestedOrientation(ActivityInfo.SCREEN_ORIENTATION_LANDSCAPE);
break;
case Configuration.ORIENTATION_PORTRAIT:
setRequestedOrientation(ActivityInfo.SCREEN_ORIENTATION_PORTRAIT);
break;
default:
setRequestedOrientation(ActivityInfo.SCREEN_ORIENTATION_UNSPECIFIED);
}
}
onConfigurationChanged is called when the screen rotates. (onCreate is no longer called when screen rotates due to manifest, see: android:configChanges)
What part of the manifest tells it "don't call onCreate()"?
Also,
Google's docs say to avoid using android:configChanges (except as a last resort).... But then the alternate methods they suggest all DO use android:configChanges.
It has been my experience that the emulator ALWAYS calls onCreate() upon rotation.
But the 1-2 devices that I run the same code on... do not.
(Not sure why there would be any difference.)
Add this line in manifest : android:configChanges="orientation|screenSize"
onConfigurationChanged is called when the screen rotates. (onCreate is no longer called when screen rotates due to manifest, see: android:configChanges)
What part of the manifest tells it "don't call onCreate()"?
Also,
Google's docs say to avoid using android:configChanges (except as a last resort).... But then the alternate methods they suggest all DO use android:configChanges.
It has been my experience that the emulator ALWAYS calls onCreate() upon rotation.
But the 1-2 devices that I run the same code on... do not.
(Not sure why there would be any difference.)
One of the best component of android architechure introduce by google will fulfill your all the requirement that is ViewModel.
That is designed to store and manage UI related data in lifecycle way plus that will allow data to survive as screen rotates
class MyViewModel : ViewModel() {
Please refer this:https://developer.android.com/topic/libraries/architecture/viewmodel
add this code to your menufests.xml .
this is your activity.
<activity
....
..
android:configChanges="orientation|screenSize"/>
I just simply added
android:configChanges="keyboard|keyboardHidden|orientation"
in the manifest file and did not add any onConfigurationChanged method in my activity.
So every time the keyboard slides out or in nothing happens.
Fix the screen orientation (landscape or portrait) in AndroidManifest.xml
android:screenOrientation="portrait" or android:screenOrientation="landscape"
for this your onResume() method is not called.
Update for Android 3.2 and higher:
Caution: Beginning with Android 3.2 (API level 13), the "screen size" also changes when the device switches between portrait and landscape orientation. Thus, if you want to prevent runtime restarts due to orientation change when developing for API level 13 or higher (as declared by the minSdkVersion and targetSdkVersion attributes), you must include the
"screenSize"value in addition to the"orientation"value. That is, you must declareandroid:configChanges="orientation|screenSize". However, if your application targets API level 12 or lower, then your activity always handles this configuration change itself (this configuration change does not restart your activity, even when running on an Android 3.2 or higher device).
Add this line to your manifest :-
android:configChanges="orientation|keyboard|keyboardHidden|screenSize|screenLayout|uiMode"
and this snippet to the activity :-
@Override
public void onConfigurationChanged(Configuration newConfig) {
super.onConfigurationChanged(newConfig);
getWindow().setFlags(WindowManager.LayoutParams.FLAG_FULLSCREEN,
WindowManager.LayoutParams.FLAG_FULLSCREEN);
}
You can lock to the current orientation of screen using this code...
int currentOrientation =context.getResources().getConfiguration().orientation;
if (currentOrientation == Configuration.ORIENTATION_PORTRAIT) {
((Activity) context).setRequestedOrientation(ActivityInfo.SCREEN_ORIENTATION_PORTRAIT);
} else {
((Activity) context). setRequestedOrientation(ActivityInfo.SCREEN_ORIENTATION_LANDSCAPE);
}
what I did...
in the manifest, to the activity section, added:
android:configChanges="keyboardHidden|orientation"
in the code for the activity, implemented:
//used in onCreate() and onConfigurationChanged() to set up the UI elements
public void InitializeUI()
{
//get views from ID's
this.textViewHeaderMainMessage = (TextView) this.findViewById(R.id.TextViewHeaderMainMessage);
//etc... hook up click listeners, whatever you need from the Views
}
//Called when the activity is first created.
@Override
public void onCreate(Bundle savedInstanceState)
{
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
InitializeUI();
}
//this is called when the screen rotates.
// (onCreate is no longer called when screen rotates due to manifest, see: android:configChanges)
@Override
public void onConfigurationChanged(Configuration newConfig)
{
super.onConfigurationChanged(newConfig);
setContentView(R.layout.main);
InitializeUI();
}
There are multiple ways to do this:
Handle orientation changes by yourself
Another alternative is to handle the orientation changes by yourself. But this is not considered a good practice.
Add this to your manifest file.
android:configChanges="keyboardHidden|orientation"
for Android 3.2 and later:
android:configChanges="keyboardHidden|orientation|screenSize"
@Override
public void onConfigurationChanged(Configuration config) {
super.onConfigurationChanged(config);
if (newConfig.orientation == Configuration.ORIENTATION_PORTRAIT) {
//Handle rotation from landscape to portarit mode here
} else if (newConfig.orientation == Configuration.ORIENTATION_LANDSCAPE){
//Handle rotation from portrait to landscape mode here
}
}
OR Restrict rotation
You can also confine your activity to portrait or landscape mode to avoid rotation.
Add this to the activity tag in your manifest file:
android:screenOrientation="portrait"
Or implement this programmatically in your activity:
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setRequestedOrientation(ActivityInfo.SCREEN_ORIENTATION_PORTRAIT);
}
OR Save Activity State
You can save the activity state in onSaveInstanceState.
@Override
public void onSaveInstanceState(Bundle outState) {
/*Save your data to be restored here
Example : outState.putLong("time_state", time); , time is a long variable*/
super.onSaveInstanceState(outState);
}
and then use the bundle to restore the state.
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
if(savedInstanceState!= null){
/*When rotation occurs
Example : time = savedInstanceState.getLong("time_state", 0); */
} else {
//When onCreate is called for the first time
}
}
You can lock to the current orientation of screen using this code...
int currentOrientation =context.getResources().getConfiguration().orientation;
if (currentOrientation == Configuration.ORIENTATION_PORTRAIT) {
((Activity) context).setRequestedOrientation(ActivityInfo.SCREEN_ORIENTATION_PORTRAIT);
} else {
((Activity) context). setRequestedOrientation(ActivityInfo.SCREEN_ORIENTATION_LANDSCAPE);
}
People are saying that you should use
android:configChanges="keyboardHidden|orientation"
But the best and most professional way to handle rotation in Android is to use the Loader class. It's not a famous class(I don't know why), but it is way better than the AsyncTask. For more information, you can read the Android tutorials found in Udacity's Android courses.
Of course, as another way, you could store the values or the views with onSaveInstanceState and read them with onRestoreInstanceState. It's up to you really.
Put the code below inside your <activity> tag in Manifest.xml:
android:configChanges="screenLayout|screenSize|orientation"
Use orientation listener to perform different tasks on different orientation.
@Override
public void onConfigurationChanged(Configuration myConfig)
{
super.onConfigurationChanged(myConfig);
int orient = getResources().getConfiguration().orientation;
switch(orient)
{
case Configuration.ORIENTATION_LANDSCAPE:
setRequestedOrientation(ActivityInfo.SCREEN_ORIENTATION_LANDSCAPE);
break;
case Configuration.ORIENTATION_PORTRAIT:
setRequestedOrientation(ActivityInfo.SCREEN_ORIENTATION_PORTRAIT);
break;
default:
setRequestedOrientation(ActivityInfo.SCREEN_ORIENTATION_UNSPECIFIED);
}
}
Even though it is not "the Android way" I have gotten very good results by handling orientation changes myself and simply repositioning the widgets within a view to take the altered orientation into account. This is faster than any other approach, because your views do not have to be saved and restored. It also provides a more seamless experience to the user, because the respositioned widgets are exactly the same widgets, just moved and/or resized. Not only model state, but also view state, can be preserved in this manner.
RelativeLayout can sometimes be a good choice for a view that has to reorient itself from time to time. You just provide a set of portrait layout params and a set of landscaped layout params, with different relative positioning rules on each, for each child widget. Then, in your onConfigurationChanged() method, you pass the appropriate one to a setLayoutParams() call on each child. If any child control itself needs to be internally reoriented, you just call a method on that child to perform the reorientation. That child similarly calls methods on any of its child controls that need internal reorientation, and so on.
You may use ViewModel object in your activity.
ViewModel objects are automatically retained during configuration changes so that data they hold is immediately available to the next activity or fragment instance. Read more:
https://developer.android.com/topic/libraries/architecture/viewmodel
Put this below code in your Activity in Android Manifest.
android:configChanges="orientation"
This will not restart your activity when you would change orientation.
add this code to your menufests.xml .
this is your activity.
<activity
....
..
android:configChanges="orientation|screenSize"/>
Every time when screen is rotated, opened activity is finished and onCreate() is called again.
1 . You can do one thing save the state of activity when screen is rotated so that, You can recover all old stuff when activity's onCreate() is called again. Refer this link
2 . If you want to prevent restarting of the activity just place following lines in your manifest.xml file.
<activity android:name=".Youractivity"
android:configChanges="orientation|screenSize"/>
You might also consider using the Android platform's way of persisting data across orientation changes: onRetainNonConfigurationInstance() and getLastNonConfigurationInstance().
This allows you to persist data across configuration changes, such as information you may have gotten from a server fetch or something else that's been computed in onCreate or since, while also allowing Android to re-layout your Activity using the xml file for the orientation now in use.
It should be noted that these methods are now deprecated (although still more flexible than handling orientation change yourself as most of the above solutions suggest) with the recommendation that everyone switch to Fragments and instead use setRetainInstance(true) on each Fragment you want to retain.
What you describe is the default behavior. You have to detect and handle these events yourself by adding:
android:configChanges
to your manifest and then the changes that you want to handle. So for orientation, you would use:
android:configChanges="orientation"
and for the keyboard being opened or closed you would use:
android:configChanges="keyboardHidden"
If you want to handle both you can just separate them with the pipe command like:
android:configChanges="keyboardHidden|orientation"
This will trigger the onConfigurationChanged method in whatever Activity you call. If you override the method you can pass in the new values.
Hope this helps.
Even though it is not "the Android way" I have gotten very good results by handling orientation changes myself and simply repositioning the widgets within a view to take the altered orientation into account. This is faster than any other approach, because your views do not have to be saved and restored. It also provides a more seamless experience to the user, because the respositioned widgets are exactly the same widgets, just moved and/or resized. Not only model state, but also view state, can be preserved in this manner.
RelativeLayout can sometimes be a good choice for a view that has to reorient itself from time to time. You just provide a set of portrait layout params and a set of landscaped layout params, with different relative positioning rules on each, for each child widget. Then, in your onConfigurationChanged() method, you pass the appropriate one to a setLayoutParams() call on each child. If any child control itself needs to be internally reoriented, you just call a method on that child to perform the reorientation. That child similarly calls methods on any of its child controls that need internal reorientation, and so on.
It is very simple just do the following steps:
<activity
android:name=".Test"
android:configChanges="orientation|screenSize"
android:screenOrientation="landscape" >
</activity>
This works for me :
Note: orientation depends on your requitement
The approach is useful but is incomplete when using Fragments.
Fragments usually get recreated on configuration change. If you don't wish this to happen, use
setRetainInstance(true); in the Fragment's constructor(s)
This will cause fragments to be retained during configuration change.
http://developer.android.com/reference/android/app/Fragment.html#setRetainInstance(boolean)
One of the best component of android architechure introduce by google will fulfill your all the requirement that is ViewModel.
That is designed to store and manage UI related data in lifecycle way plus that will allow data to survive as screen rotates
class MyViewModel : ViewModel() {
Please refer this:https://developer.android.com/topic/libraries/architecture/viewmodel
I just simply added
android:configChanges="keyboard|keyboardHidden|orientation"
in the manifest file and did not add any onConfigurationChanged method in my activity.
So every time the keyboard slides out or in nothing happens.
Source: Stackoverflow.com