java - Can someone who uses android studio tell me what to do? -

my app shuts down when clicking button, knows why? , if fins errors please tell me ;)this activity 2 buttons when pressed show timepickerdialog , save time.

here's code:

package app.alexdickson.com.workout1;  import android.app.dialog; import android.app.timepickerdialog; import android.support.v7.app.appcompatactivity; import android.os.bundle; import android.view.view; import android.widget.imagebutton; import android.widget.timepicker; import android.widget.toast;   public class main2activity extends appcompatactivity implements   view.onclicklistener{ imagebutton botoflexio; imagebutton botoabdominals; static final int dialog_id = 0; int hour_x; int minute_x; int hourdefinitivaflexio; int minutedefinitvaflexio; int hourdefinitivaabs; int minutedefinitivaabs;  @override protected void oncreate(bundle savedinstancestate) {      super.oncreate(savedinstancestate);     setcontentview(r.layout.activity_main2);      botoflexio = (imagebutton) findviewbyid(r.id.botoflexio);     botoabdominals =  (imagebutton) findviewbyid(r.id.botoabdominals);  botoflexio.setonclicklistener(this);  botoabdominals.setonclicklistener(this);   }  @override public void onclick(view v) {     switch (v.getid()){         case r.id.botoflexio:             botoflexio.setbackgroundresource(r.drawable.flexioclicat);             showdialog(dialog_id);             hourdefinitivaflexio = hour_x;             minutedefinitvaflexio = minute_x;             break;          case r.id.botoabdominals:             botoflexio.setbackgroundresource(r.drawable.abdominalsclicat);             showdialog(dialog_id);             hourdefinitivaabs = hour_x;             minutedefinitivaabs = minute_x;             break;      } }  @override protected dialog oncreatedialog(int id) {     if (id == dialog_id)          return new timepickerdialog(main2activity.this, ktimepickerlistener, hour_x, minute_x, true);     return null; }  protected timepickerdialog.ontimesetlistener ktimepickerlistener =         new timepickerdialog.ontimesetlistener() {             @override             public void ontimeset(timepicker view, int hourofday, int minute) {                 hour_x = hourofday;                 minute_x = minute;                 toast.maketext(main2activity.this, hour_x + ": " + minute_x, toast.length_long).show();             }         }; 

and here's xml:

<?xml version="1.0" encoding="utf-8"?> <linearlayout   xmlns:android="http://schemas.android.com/apk/res/android" android:layout_width="match_parent" android:layout_height="wrap_content" android:weightsum="2" android:orientation="horizontal" android:theme="@android:style/theme.black.notitlebar.fullscreen" >  <imagebutton     android:layout_width="0dp"     android:layout_height="400dp"     android:layout_weight="1"     android:id="@+id/botoabdominals"     android:background="@drawable/abdominals"     android:contentdescription="imatgeabdominals"     android:layout_margintop="50dp"     android:layout_marginright="10dp"     android:layout_marginleft="10dp"     />   <imagebutton     android:layout_width="0dp"     android:layout_height="400dp"     android:layout_weight="1"     android:id="@+id/botoflexio"     android:layout_gravity="top"     android:layout_margintop="50dp"     android:layout_marginleft="10dp"     android:layout_marginright="10dp"     android:background="@drawable/flexio"     android:contentdescription="imatgeflexio"     /> 

thanks !!!!

register listener button after initialize it.

 botoflexio.setonclicklistener(this);  botoabdominals.setonclicklistener(this);