What is wrong with this Android code that uses the parse.com database to store data -

string nametxt; string bloodtxt; string agetxt; string mobiletxt; button register; edittext name; edittext age; edittext blood; edittext mobile;    @override protected void oncreate(bundle savedinstancestate) {     super.oncreate(savedinstancestate);     setcontentview(r.layout.activity_register);     name = (edittext) findviewbyid(r.id.name);     age = (edittext) findviewbyid(r.id.age);     blood = (edittext)findviewbyid(r.id.blood);     age = (edittext)findviewbyid(r.id.age);     register =(button)findviewbyid(r.id.register);     register.setonclicklistener(new view.onclicklistener() {         @override         public void onclick(view v) {             nametxt = name.gettext().tostring();             agetxt = age.gettext().tostring();             bloodtxt = blood.gettext().tostring();//logcat pointing exception here//             mobiletxt = mobile.gettext().tostring();             if (nametxt.equals("") && agetxt.equals("")) {                 toast.maketext(getapplicationcontext(),                         "please complete sign form",                         toast.length_long).show();             }             else             {                 parseuser user = new parseuser();                 user.setusername(nametxt);                 user.setpassword(agetxt);                 user.put("blood", bloodtxt);                 user.put("mobile",mobiletxt);                 user.signupinbackground(new signupcallback() {                     @override                     public void done(parseexception e) {                         if (e == null) {                             toast.maketext(getapplicationcontext(), "succesfully registered", toast.length_long).show();                         } else {                             toast.maketext(getapplicationcontext(), "hey %d registered in blood database.." + nametxt, toast.length_long).show();                           }                     }                 });             }          }     });  } 

i'm getting error:

process: com.blooddata.lemuriadigitallab.blooddata, pid: 26845 java.lang.nullpointerexception: attempt invoke virtual method 'android.text.editable android.widget.edittext.gettext()' on null object reference @ com.blooddata.lemuriadigitallab.blooddata.register$1.onclick(register.java:43) @ android.view.view.performclick(view.java:5181) @ android.view.view$performclick.run(view.java:20887) @ android.os.handler.handlecallback(handler.java:739) @ android.os.handler.dispatchmessage(handler.java:95) @ android.os.looper.loop(looper.java:145) @ android.app.activitythread.main(activitythread.java:5942) @ java.lang.reflect.method.invoke(native method) @ java.lang.reflect.method.invoke(method.java:372) @ com.android.internal.os.zygoteinit$methodandargscaller.run(zygoteinit.java:1400) @ com.android.internal.os.zygoteinit.main(zygoteinit.java:1195)

initialize "mobile" edittext variable.

the nullpointerexception raised here:

  mobile.gettext().tostring();