android - How to call a method of another class from onAuthenticationSucceeded method? -

i have used fingerprint login in android app. if authentication success,it call onauthenticationsucceeded method. after success authentication of fingerprint want verify username within onauthenticationsucceeded. couldn't call method(for verifying username) of class within onauthenticationsucceeded method. app seems stopped.

how acheive it? please me. thank you

• this in fingerprinthandler.java

  public void onauthenticationsucceeded(fingerprintmanager.authenticationresult result{ login log=new login(); log.unamecheck(); }

• this method in login.java

public void unamecheck(){ string uname=edit_username.gettext().tostring(); string storedpassword=mydb.getsingleentry(uname); if(storedpassword!=0){ toast.maketext(login.this,"login successfull",toast.length_long).show(); intent intent =new intent("michel.maan.login1"); startactivity(intent); } else{ toast.maketext(login.this,"login failed",toast.length_long).show(); } }

• this databasehelper.java

  public string getsingleentry(string username){ sqlitedatabase db=this.getwritabledatabase(); cursor cursor=db.query("user_table".null,"name=?",new string[]{username},null,null,null); if(cursor.getcount()<1){
cursor.close();
return"not exist"; } cursor.movetofirst(); string password=cursor.getstring(cursor.getcolumnindex("password")); cursor.close(); return password; }

• the exception showing in android monitor is

  java.lang.nullpointerexceptio:attempt invoke virtual method 'android.content.res.resources android.content.context.getresources()' on null object reference

this code referred project android authority

simplest way startactivity on onauthenticatinsucceed method , pass intent

intent intent=new intent(this,secondactivity.class); intent.putextra("authentication","done"); startactivity(intent); 

and in oncreate of secondactiviy , check this

if(getintent.getextra("authentication").equals("done"))  callverifyusername(); 

and if want can pass username fingerprintactivity in intent. if want previous screen if username not verified can call

finish();