java - Object is null set in Defalut add Card in Arraylist -


i create default class see list cart in app 

 public class default extends application {   public arraylist<card> listcard;          public arraylist<card> getlistcard() {             return listcard;         }          public void setlistcard(arraylist<card> listcard) {             this.listcard = listcard;         }      }

next when

public class scanqrcodeactivity extends appcompatactivity {       private arraylist<card> cardlist;

....

                    if (hotpvalue.equals(passwordhotp)) {                          card card = new card(path3, base32, namecard, intervaltotp, passwordhotp, getdate(), expirationdate, hotpvalue);                        default app = (default) getapplicationcontext();                             cardlist = app.getlistcard();                             cardlist.add(card); // show error line code                              app.setlistcard(cardlist);                             cardlist = new arraylist<card>();                             cardlist= app.getlistcard();                             system.out.println("dodanokarte"+card.getnamecard());                      }

see log

process: com.novum.smrtkarta, pid: 13844 java.lang.nullpointerexception: attempt invoke virtual method 'boolean java.util.arraylist.add(java.lang.object)' on null object reference @ com.xxxx.smrtkarta.activity.scanqrcodeactivity$3$1.run(scanqrcodeactivity.java:277) @ android.os.handler.handlecallback(handler.java:739) @ android.os.handler.dispatchmessage(handler.java:95) @ android.os.looper.loop(looper.java:148) @ android.app.activitythread.main(activitythread.java:5417) @ java.lang.reflect.method.invoke(native method) @ com.android.internal.os.zygoteinit$methodandargscaller.run(zygoteinit.java:726) @ com.android.internal.os.zygoteinit.main(zygoteinit.java:616)

what wrong ?

this should work have change change:

arraylist<card> listcard

to:

arraylist<card> list = new arraylist<card>;

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