java - Updating each second in Android -

i making app counts every second based on rate of pay, , written now, crashes on startup.

am doing thread section wrong?

i kind of new android, bit unclear on oncreate method in general. clarification , how relates code helpful well.

the button supposed start count. think it's crashing due t.start() line, don't know how trigger event.

package com.example.terik.myapplication;  import android.os.bundle; import android.support.v7.app.actionbaractivity; import android.view.menu; import android.view.menuitem; import android.widget.textview;   public class mainactivity extends actionbaractivity {      @override     protected void oncreate(bundle savedinstancestate) {         super.oncreate(savedinstancestate);         setcontentview(r.layout.activity_main);         textview text2;         text2 = (textview) findviewbyid(r.id.textview2);          thread t = new thread() {              @override             public void run() {                 try {                     while (!isinterrupted()) {                         thread.sleep(1000);                         runonuithread(new runnable() {                             @override                             public void run() {                                 updatetextview();                             }                         });                     }                 } catch (interruptedexception e) {                 }             }         };          t.start();     }      private void updatetextview() {         textview text2;         double update;         double rateofpay = 9.00;         text2 = (textview)findviewbyid(r.id.textview2);        charsequence newtime = text2.gettext();         int number = integer.parseint(newtime.tostring());         update = number+ rateofpay;         text2.settext((int) update);      }         @override     public boolean oncreateoptionsmenu(menu menu) {         // inflate menu; adds items action bar if present.         getmenuinflater().inflate(r.menu.menu_main, menu);         return true;     }      @override     public boolean onoptionsitemselected(menuitem item) {         // handle action bar item clicks here. action bar         // automatically handle clicks on home/up button, long         // specify parent activity in androidmanifest.xml.         int id = item.getitemid();          //noinspection simplifiableifstatement         if (id == r.id.action_settings) {             return true;         }          return super.onoptionsitemselected(item);     } } 

one problem numberformatexception when trying parse double integer.

the other problem trying call settext() int on line:

text2.settext((int) update); 

this fixed it:

private void updatetextview() {     textview text2;     double update;     double rateofpay = 9.00;     text2 = (textview)findviewbyid(r.id.textview2);     charsequence newtime = text2.gettext();     double number = double.parsedouble(newtime.tostring());     update = number+ rateofpay;     text2.settext(string.valueof(update)); } 

edit:

here's how start thread when click button. first make thread t instance variable, can accessed in button click run() method (you might want re-name method too!).

i tested this, worked me:

public class mainactivity extends actionbaractivity {      thread t;      @override     protected void oncreate(bundle savedinstancestate) {         super.oncreate(savedinstancestate);         setcontentview(r.layout.activity_main);         textview text2;         text2 = (textview) findviewbyid(r.id.textview2);          t = new thread() {              @override             public void run() {                 try {                     while (!isinterrupted()) {                         thread.sleep(1000);                         runonuithread(new runnable() {                             @override                             public void run() {                                 updatetextview();                             }                         });                     }                 } catch (interruptedexception e) {                 }             }         };      }      public void run(view v) {         t.start();     }      private void updatetextview() {         textview text2;         double update;         double rateofpay = 9.00;         text2 = (textview)findviewbyid(r.id.textview2);         charsequence newtime = text2.gettext();         double number = double.parsedouble(newtime.tostring());         update = number+ rateofpay;         text2.settext(string.valueof(update));     }      //......... 

edit 2:

as @bladecoder mentioned in comments, thread over-kill this. using handler , postdelayed() best route this.

also, better make textview instance variable don't create new reference every time update it.

i tested version well:

public class mainactivity extends actionbaractivity {      textview text2;     handler handler;      @override     protected void oncreate(bundle savedinstancestate) {         super.oncreate(savedinstancestate);         setcontentview(r.layout.activity_main);          text2 = (textview) findviewbyid(r.id.textview2);          handler = new handler();      }      runnable updatetext = new runnable(){         @override         public void run(){             updatetextview();             handler.postdelayed(this, 1000);         }     };      public void run(view v) {         handler.postdelayed(updatetext, 1000);     }      private void updatetextview() {          double update;         double rateofpay = 9.00;         charsequence newtime = text2.gettext();         double number = double.parsedouble(newtime.tostring());         update = number+ rateofpay;         text2.settext(string.valueof(update));     }      //.............