Null Pointer using SharedPreferences

Question

I am passing and showing values from one activity to another activity, and making file name using those string like this:

 AU_20140312_160107_65.jpg

AU - simple prefix

20140312_160107 - yyyyMMdd_HHmmss

6 - event_id (getting from LoginActivity.java)

5 - operative_id (getting from LoginActivity.java)

see my code below:

LoginActivity.java:

static SharedPreferences sharedprefs;

static String event_id, operative_id ;

sharedprefs = getApplicationContext().getSharedPreferences(
    "com.example.app", Context.MODE_PRIVATE);


 Intent intent = getIntent();
 event_id = intent.getStringExtra("event_id");
 sharedprefs.edit().putString("EVENT_ID", event_id).commit();
 operative_id = intent.getStringExtra("operative_id");
 sharedprefs.edit().putString("OPERATIVE_ID", operative_id).commit();

CameraLauncherActivity.java:

static File getOutputMediaFile() {


            String event_ID = LoginActivity.sharedprefs.getString("EVENT_ID", null);
            Log.d("shared >>> eventID : ", event_ID);
            String operative_ID = LoginActivity.sharedprefs.getString("OPERATIVE_ID", null);
            Log.d("shared >>> operativeID : ", operative_ID);

            timeStamp = new SimpleDateFormat("yyyyMMdd_HHmmss")
            .format(new Date());            

            // file name
                mediaFile = new File(LoginActivity.mediaStorageDir.getPath() + File.separator
        + "AU_" + timeStamp + "_" + event_ID + operative_ID + ".jpg");

            return mediaFile;
        }

when launching first time, Log says:

shared >>> eventID :(29917): 12
shared >>> operativeID :(29917): 4

like you can see above, everything works fine, and getting eventID and operativeID using log as well

but once i will launch my app again, after closing it, and caputre image, then getting NPE and Log :

FATAL EXCEPTION: main
java.lang.NullPointerException: println needs a message
at android.util.Log.println_native(Native Method)
at android.util.Log.d(Log.java:155)
 app.mac.Camera.CameraLauncherActivity.getOutputMediaFile(CameraLauncherActivity.java:386)
at app.mac.Camera.CameraLauncherActivity$2.onPictureTaken(CameraLauncherActivity.java:362)
at android.hardware.Camera$EventHandler.handleMessage(Camera.java:789)
at android.os.Handler.dispatchMessage(Handler.java:99)
at android.os.Looper.loop(Looper.java:137)
at android.app.ActivityThread.main(ActivityThread.java:4921)
at java.lang.reflect.Method.invokeNative(Native Method)
at java.lang.reflect.Method.invoke(Method.java:511)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1036)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:803)
at dalvik.system.NativeStart.main(Native Method)

u need to saved values onPause() and load older values in onResume() — M D, Mar 13 '14 at 06:50

score 1 · Accepted Answer · answered Mar 13 '14 at 06:52

1

Instead of assigning the values directly to the variables event_id and operative_id store them in the db or preferences.

Instead of directly assigning like this this : event_id = intent.getStringExtra("event_id"); operative_id = intent.getStringExtra("operative_id");

check the intent.getStringExtra("event_id") and intent.getStringExtra("operative_id") for null.

If null fetch from stored values. If not null assign to variables and overwrite stored values with the new one for next time.

answered Mar 13 '14 at 06:52

Viral Patel

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I meant SharedPreferences. Refer this question to know how to do it. http://stackoverflow.com/questions/3624280/how-to-use-sharedpreferences-in-android-to-store-fetch-and-edit-values – Viral Patel Mar 13 '14 at 07:11
more on the class - [SharedPreferences](http://developer.android.com/reference/android/content/SharedPreferences.html) – Viral Patel Mar 13 '14 at 07:13

score 0 · Answer 2 · edited Mar 13 '14 at 07:27

//Initialization 
SharedPreferences _mypref = getApplicationContext().getSharedPreferences("mypref", 0);

//store data in shared preferences
Editor editor = _mypref.edit();

//Storing boolean - true/false;     
editor.putBoolean("key_name", true);  

//Storing string
editor.putString("key_name", "string value");

//Storing integer
editor.putInt("key_name", "int value");    

//Storing float
editor.putFloat("key_name", "float value");       

//Storing long 
editor.putLong("key_name", "long value"); 

//commit changes
editor.commit();       

// retrive data

//getting String
_mypref .getString("key_name", null); 

//getting Integer
_mypref .getInt("key_name", null);         

//getting Float
_mypref .getFloat("key_name", null);   

//getting Long
_mypref .getLong("key_name", null);    


//getting boolean
_mypref.getBoolean("key_name", null);     


//remove Data
editor.remove("name");
editor.commit();


//Clear all Data 
editor.clear();
editor.commit();

@Moon For More You can refer this : http://androiddevelopmentworld.blogspot.in/2013/04/shared-preferences-in-android.html :) — Hardik Joshi, Mar 13 '14 at 07:23

Null Pointer using SharedPreferences

2 Answers2