java - Attempt to invoke interface method android -

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• what nullpointerexception, , how fix it? 12 answers

i have code in class a

 private rtclistener mlistener;  @override public void update(string string) {     //here work want pass data interface           mlistener.onupdate(sometext);   }   public interface rtclistener{      void onupdate(string string);  } 

now in class , b

i implements interface

public class b extends service implements a.rtclistener{  // here override interface method   @override public void onupdate(string string) {   log.d("dwdwadwadwd"," data is"+string);  }    } 

its give me error

 attempt invoke interface method 'void .....  on null object reference 

i solve in class b

construct class

a in class b

a myclass = new a(this,another prameter if u have,another prameter if u have); 

and in class a on construct function this

public a(rtclistener l , other prameter , other prameter){ //construct method //rtclistener  interface name mlistener = l; } 

just sure code interface code above in question implements

that's :)