file - check if SharedPrefecences exists in Android -


i want check if have save data in shared preferences read file, because if file not exist , app wont work.

i search stack overflow , offered this:

file f = new file( "/data/data/your_application_package/shared_prefs/name_of_your_preference.xml"); if (f.exists()){     sharedpreferences prefs = getpreferences(mode_private);     string restoredtext = prefs.getstring("text", null); } else     log.d("tag", "setup default preferences");

now don't know use correctly or not. , save pref:

sharedpreferences.editor editor = getpreferences(mode_private).edit(); editor.putstring("text", showcounttv.gettext().tostring()); editor.apply();

edited: of course know can :

sharedpreferences prefs = getpreferences(mode_private); string restoredtext = prefs.getstring("text", null);

but when @ first time app installed because nothing have been saved , program crashed.this logcat:

06-19 09:53:25.794  20485-20485/com.pirisalavat.amirhossein.amir d/androidruntime﹕ shutting down vm 06-19 09:53:25.795  20485-20485/com.pirisalavat.amirhossein.amir e/androidruntime﹕ fatal exception: main     process: com.pirisalavat.amirhossein.amir, pid: 20485     java.lang.runtimeexception: unable start activity componentinfo{com.pirisalavat.amirhossein.amir/com.pirisalavat.amirhossein.amir.mainactivity}: java.lang.nullpointerexception: attempt invoke virtual method 'java.lang.string java.lang.string.tostring()' on null object reference             @ android.app.activitythread.performlaunchactivity(activitythread.java:2325)             @ android.app.activitythread.handlelaunchactivity(activitythread.java:2390)             @ android.app.activitythread.access$800(activitythread.java:151)             @ android.app.activitythread$h.handlemessage(activitythread.java:1303)             @ android.os.handler.dispatchmessage(handler.java:102)             @ android.os.looper.loop(looper.java:135)             @ android.app.activitythread.main(activitythread.java:5257)             @ java.lang.reflect.method.invoke(native method)             @ java.lang.reflect.method.invoke(method.java:372)             @ com.android.internal.os.zygoteinit$methodandargscaller.run(zygoteinit.java:903)             @ com.android.internal.os.zygoteinit.main(zygoteinit.java:698)      caused by: java.lang.nullpointerexception: attempt invoke virtual method 'java.lang.string java.lang.string.tostring()' on null object reference             @ com.pirisalavat.amirhossein.amir.mainactivity.getdataformsharedpref(mainactivity.java:73)             @ com.pirisalavat.amirhossein.amir.mainactivity.oncreate(mainactivity.java:30)             @ android.app.activity.performcreate(activity.java:5990)             @ android.app.instrumentation.callactivityoncreate(instrumentation.java:1106)             @ android.app.activitythread.performlaunchactivity(activitythread.java:2278)             at android.app.activitythread.handlelaunchactivity(activitythread.java:2390)             at android.app.activitythread.access$800(activitythread.java:151)             at android.app.activitythread$h.handlemessage(activitythread.java:1303)             at android.os.handler.dispatchmessage(handler.java:102)             at android.os.looper.loop(looper.java:135)             at android.app.activitythread.main(activitythread.java:5257)             at java.lang.reflect.method.invoke(native method)             at java.lang.reflect.method.invoke(method.java:372)             at com.android.internal.os.zygoteinit$methodandargscaller.run(zygoteinit.java:903)             at com.android.internal.os.zygoteinit.main(zygoteinit.java:698)

there sharedpreferences method called contains can use purpose: 

if (getpreferences(mode_private).contains("text")) {     // }

and don't recommend creating file pointing sharedpreferences - can't know sure file created in directory called "/data/data/your_application_package/shared_prefs" - there plenty of vendors , each of them has plenty of devices, file can contained somewhere else/its name different/etc. contains() enough.


Comments

Post a Comment

Popular posts from this blog

How to connect android app to App engine -

i'm trying connect app in android server i've opened on appengine. my server's name : dddd-daniel-2345 , website server : http://dddd-daniel-2345.appspot.com/ this how connect android app server in app engine: app.yaml: application: dddd-daniel-2345 version: 1 runtime: python27 api_version: 1 threadsafe: yes handlers: - url: .* script: main.app libraries: - name: webapp2 version: "2.5.2" main.py: #!/usr/bin/env python # # copyright 2007 google inc. google.appengine.api import users import webapp2 class userhandler(webapp2.requesthandler): def get(self): user = users.get_current_user() if user: greeting = ('%s,%s,%s' % (user.email(),user.user_id(),user.nickname())) else: greeting = ('not logged in') self.response.out.write(greeting) app = webapp2.wsgiapplication([('/', userhandler),], debug=true) my applications code : add manifast main....
Read more

gcc - MinGW's ld cannot perform PE operations on non PE output file -

i know there other similar questions out there, stackoverflow or not. i've researched lot this, , still didn't find single solution. i'm doing operative system side project. i've been doing in assembly, wanna join c code. test, made assembly code file (called test.asm): [bits 32] global _a section .text _a: jmp $ then made c file (called main.c): extern void a(void); int main(void) { a(); } to link, used file (called make.bat): "c:\mingw\bin\gcc.exe" -ffreestanding -c -o c.o main.c nasm -f coff -o asm.o test.asm "c:\mingw\bin\ld.exe" -ttext 0x100000 --oformat binary -o out.bin c.o asm.o pause i've been researching ages, , i'm still struggling find answer. hope won't flagged duplicate. acknowledge existence of similar questions, have different answers, , none work me. question: what doing wrong? old mingw versions had problem "ld" not able create non-pe files @ all. maybe current versions...
Read more

php - display validation error message next to the textbox in codeigniter -

Image
i'm newbie codeigniter.i want display error message next text box.my view file create.php contains following code. <?php echo validation_errors(); //validation echo form_open('news/create'); //create form ?> <div class="boxes"> <div class="common"> <div class="lables"> <label for="name">name</label> </div> <div class="text_boxes"> <input type="text" name="uname" /><div id="infomessage"><?php echo $message;?></br> </div> </div>` and below controller model: public function create() { $this->load->helper('form'); $this->load->library('form_validation'); $data['title'] = 'insert items'; $this->form_validation->set_rules('uname','required|min_length[6]|m...
Read more