Android using shared preference and Dispatcher activity, to get back to the last activity (after reboot the phone)

Question

I'm using a Shared Preferences to save the state of my application to be able to get to the last activity before my Android Handphone got re-boot-ed. My purpose is when Android system manage the memory and push out my apps, when users re-enter to the apps, they will get to the last Activity and screen of my apps.

And this is some of my code :

First is DispatcherActivity.java :

> package com.lm.rosary;
> 
> import android.app.Activity; import android.content.Intent; import
> android.content.SharedPreferences; import android.os.Bundle;
> 
> 
> public class DispatcherActivity extends Activity {
> 
>       @Override
>       protected void onCreate(Bundle savedInstanceState) {
>           super.onCreate(savedInstanceState);
> 
>           Class<?> activityClass;
> 
>           try {
>               SharedPreferences prefs = getSharedPreferences("X", MODE_PRIVATE);
>               activityClass = Class.forName(
>                   prefs.getString("lastActivity", Jfp1.class.getName()));
>           } catch(ClassNotFoundException ex) {
>               activityClass = Jfp1.class;
>           }
> 
>           startActivity(new Intent(this, activityClass));
>       }   }

Second is my sample activity ( Jfp1.java ) that I want users to get back to this screen when phone re-boot or re-started. Jfp1.java :

> import android.content.SharedPreferences; import
> android.content.SharedPreferences.Editor;
> 
> 
> public class Jfp1 extends Activity implements OnClickListener { .... 
> 
> SharedPreferences prefs;
> SharedPreferences.Editor editor; 
> .... @Override    protected void onPause() {      super.onPause();
>       SharedPreferences prefs = getSharedPreferences("X", MODE_PRIVATE);
>       Editor editor = prefs.edit();
>       editor.putString("lastActivity", getClass().getName());
>       editor.commit();    }

My apps, start from MainActivity to Mysterytopray and to Jfp1 class. DispatcherActivity.java is on separate class.

And third my Manifest as usual :

> <activity
>             android:name=".MainActivity"
>             android:label="@string/app_name" >
>             <intent-filter>
>                 <action android:name="android.intent.action.MAIN" />
> 
>                 <category android:name="android.intent.category.LAUNCHER" />
>             </intent-filter>
>         </activity>
>       
>         <activity
>             android:name="com.lm.rosary.DispatcherActivity"
>             android:label="@string/app_name" >
>             <intent-filter>
>                 <action android:name="android.intent.action.MAIN" />
>             </intent-filter>
>         </activity>
>         
>         <activity
>             android:name="com.lm.rosary.Jfp1"
>             android:label="@string/app_name"  >
>         </activity>

I'm on the Jfp1 screen, and I reboot the HP. But after HP restarted, I'm clicking my apps icon, but Jfp1 activity is not appeared first. Main Activity that come first. But actually, I want it to get back to the last Activity that is Jfp1.java.

I'm not experienced on Android, so anyone please give me some advice and correct my coding. Thanks a lot.

what is your exact use case? this might lead to more problems in the future especially if your Dispatcher jumps to a screen, where the screen may have been part of a flow and assumes the back stack contains the previous screens in the flow... and if the activity your jumping to is truly of depth=1 starting from your dispatcher, then why perform a jump at all? the UX should provide a straight-forward path to the activity.... these are just suggestions, knowing your exact use case would help. — Ryhan, Feb 25 '16 at 08:28

score 1 · Answer 1 · answered Feb 25 '16 at 08:16

1

You manifest specifies that MainActivity is the one opened with the application as it has the options

<intent-filter>
    <action android:name="android.intent.action.MAIN" />

    <category android:name="android.intent.category.LAUNCHER" />
</intent-filter>

If you want your process to work, you will have to make you DispatcherActivity the only main activity of your app by setting these options on it.

answered Feb 25 '16 at 08:16

malrok44

592
6
17

I have tried as you suggested, and It is work okay. . But another this happened, that is : after reboot HP and Jfp1 screen appeared, and I pressed 'back' button on HP, it is showed only blank screen. How to avoid that, so I can directly closed the apps without blank screen appeared ? Thanks a lot for your advice. – Leonard Mamangkey Feb 26 '16 at 04:38

score 1 · Answer 2 · answered Feb 25 '16 at 08:17

1

MainActivity is your launcher so it will always start.

Solution - In MainActivity onCreate read data from SharedPreference if it is Jfp1 open JFp1 screen if it is other activity start another activity and then call finish() on main activity.

answered Feb 25 '16 at 08:17

sanky jain

873
1
6
14

I tried your suggestion , and success. Thanks a lot. – Leonard Mamangkey Feb 26 '16 at 08:42
@LeonardMamangkey why did you unmarked my answer.You said it worked right? – sanky jain Mar 07 '16 at 05:28
if they are 2 or more answer that can solved the problem....only 1 green correct marks that I can put. Is there any way to have 2 or more green correct marks ? Thaks. – Leonard Mamangkey Mar 08 '16 at 06:06
I don't know way to have 2 or more green correct marks. But incase of multiple correct answers you should put correct to the one which is posted first. – sanky jain Mar 08 '16 at 06:39

Huteri · Accepted Answer · 2016-02-26T09:19:12.057

1

Use this new code

    <activity
        android:name=".MainActivity"
        android:label="@string/app_name" >
    </activity>

    <activity
        android:name="com.lm.rosary.DispatcherActivity"
        android:label="@string/app_name" >
        <intent-filter>
            <action android:name="android.intent.action.MAIN" />

            <category android:name="android.intent.category.LAUNCHER" />
        </intent-filter>
    </activity>

    <activity
        android:name="com.lm.rosary.Jfp1"
        android:label="@string/app_name"  >
    </activity>

UPDATE: Call finish() is much more appropriate, add this below

startActivity(new Intent(this, activityClass));
finish();

edited Feb 26 '16 at 09:19

answered Feb 25 '16 at 08:20

Huteri

158
2
12

I have tried as you suggested, and It is work okay. . But another this happened, that is : after reboot HP and Jfp1 screen appeared, and I pressed 'back' button on HP, it is showed only blank screen. How to avoid that, so I can directly closed the apps without blank screen appeared ? Thanks a lot for your advice. – Leonard Mamangkey Feb 26 '16 at 04:39
@LeonardMamangkey it is because DispatcherActivity is a blank page. Add intent flags Intent.FLAG_ACTIVITY_NEW_TASK – Huteri Feb 26 '16 at 05:49
where should I put that ? on the manifest ? or on the DispatcherActivity.java ? Could you please give an example for that ? Appreciate that.very much. – Leonard Mamangkey Feb 26 '16 at 08:52
Seems like you already got the answer, use finish() is simpler. – Huteri Feb 26 '16 at 09:16
thanks a lot, it is works okay and you saved my days. – Leonard Mamangkey Feb 29 '16 at 03:26

Android using shared preference and Dispatcher activity, to get back to the last activity (after reboot the phone)

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