android - nullpointerexception getSharedPreferences -

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i trying save preferences within android app. when trying sharedpreference getting nullpointerexception. error:

04-25 13:58:44.814: w/system.err(22795): java.lang.nullpointerexception 04-25 13:58:44.824: w/system.err(22795):    @ com.koeriers.standaard.sharedpreferences.setdata(sharedpreferences.java:27) 04-25 13:58:44.829: w/system.err(22795):    @ com.koeriers.standaard.actlogin.oncreate(actlogin.java:79) 04-25 13:58:44.834: w/system.err(22795):    @ android.app.activity.performcreate(activity.java:5206) 04-25 13:58:44.839: w/system.err(22795):    @ android.app.instrumentation.callactivityoncreate(instrumentation.java:1094) 04-25 13:58:44.844: w/system.err(22795):    @ android.app.activitythread.performlaunchactivity(activitythread.java:2074) 04-25 13:58:44.849: w/system.err(22795):    @ android.app.activitythread.handlelaunchactivity(activitythread.java:2135) 04-25 13:58:44.854: w/system.err(22795):    @ android.app.activitythread.access$700(activitythread.java:140) 04-25 13:58:44.859: w/system.err(22795):    @ android.app.activitythread$h.handlemessage(activitythread.java:1237) 04-25 13:58:44.864: w/system.err(22795):    @ android.os.handler.dispatchmessage(handler.java:99) 04-25 13:58:44.869: w/system.err(22795):    @ android.os.looper.loop(looper.java:137) 04-25 13:58:44.874: w/system.err(22795):    @ android.app.activitythread.main(activitythread.java:4921) 04-25 13:58:44.874: w/system.err(22795):    @ java.lang.reflect.method.invokenative(native method) 04-25 13:58:44.879: w/system.err(22795):    @ java.lang.reflect.method.invoke(method.java:511) 04-25 13:58:44.884: w/system.err(22795):    @ com.android.internal.os.zygoteinit$methodandargscaller.run(zygoteinit.java:1027) 04-25 13:58:44.889: w/system.err(22795):    @ com.android.internal.os.zygoteinit.main(zygoteinit.java:794) 04-25 13:58:44.894: w/system.err(22795):    @ dalvik.system.nativestart.main(native method)

this sharedpreferences class:

package com.myapp.standaard;  import android.os.bundle; import android.preference.preferenceactivity; import android.widget.edittext;  public class sharedpreferences extends preferenceactivity {  public static string guid = "8bb4894b-92f7-45af-9a40-b99d7a06a506"; public static string licensekey = "letmein";  edittext etlicense; android.content.sharedpreferences sharedprefs;  @override protected void oncreate(bundle savedinstancestate) {     super.oncreate(savedinstancestate);     try {         addpreferencesfromresource(r.xml.preferences);         etlicense = (edittext) findviewbyid(r.id.etlicense);     } catch (exception e) {         e.printstacktrace();     } }  public boolean setdata(string setpreference, string setvalue) {     android.content.sharedpreferences.editor editor = sharedprefs.edit();     editor.putstring(setpreference, setvalue);     editor.commit();     return true; }  public string getdata(string getpreference, string errormessage) {     sharedprefs = getsharedpreferences(getpreference, mode_private);     string returndata = sharedprefs.getstring(getpreference, errormessage);     return returndata; } }

and place in activity trying retrieve value preference:

try{          sharedpreferences sp = new sharedpreferences();         licentie = sp.getdata("licensekey", "error loading license");     } catch (exception e){         e.printstacktrace();         licentie = "";     }

you have'nt called public boolean

setdata(string setpreference, string setvalue)

anywhere why on licentie = sp.getdata("licensekey", "error loading license");

it giving nullpointerexception.

first set "licensekey" try retrieve it.

note -- kind of implementation used according me not correct.


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