How to set dropdown arrow in spinner?

I tried to set spinner with drop down arrow but i couldn't fix it can anyone help me with this? I have attached the source code. my class file: ``` import android.os.Bundle; import android.view.View; import android.widget.AdapterView; import android.widget.ArrayAdapter; import android.widget.Button; import android.widget.EditText; import android.widget.Spinner; import android.widget.AdapterView.OnItemSelectedListener; import android.widget.Toast; public class topup extends Activity { Spinner spinner,spin1,spin2,spin3; EditText ed,ed1; Button btn; List<String> list, list1,list2,list3; private String[] countries_list={"01","02","03","04","05","06","07","08","09","10","11","12"}; protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.topup); spinner = (Spinner) findViewById(R.id.spinner1); spin1= (Spinner) findViewById(R.id.spinner2); spin2= (Spinner) findViewById(R.id.spinner3); spin3= (Spinner) findViewById(R.id.spinner4); ed = (EditText) findViewById(R.id.editText3); list = new ArrayList<String>(); list.add(""); list.add("select"); list.add("01"); list.add("02"); list.add("03"); list.add("04"); list.add("05"); list.add("06"); list.add("07"); list.add("08"); list.add("09"); list.add("10"); list.add("11"); list.add("12"); ArrayAdapter<String> adp = new ArrayAdapter<String> (this, android.R.layout.simple_spinner_item, list); //adp.setDropDownViewResource(android.R.layout.simple_spinner_dropdown_item); spinner.setAdapter(adp); spinner.setOnItemSelectedListener(new OnItemSelectedListener() { //@Override public void onItemSelected(AdapterView<?> parent, View arg1,int arg2, long arg3) { // TODO Auto-generated method stub String item = spinner.getItemAtPosition(1).toString(); //Toast.makeText(spinner.getContext(), "Selected: " + item, Toast.LENGTH_LONG).show(); String ss=spinner.getSelectedItem().toString(); String } public void onNothingSelected(AdapterView<?> arg0) { // TODO Auto-generated method stub } }); ``` my xml file: ``` <?xml version="1.0" encoding="UTF-8"?> <RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android" xmlns:tools="http://schemas.android.com/tools" android:layout_width="match_parent" android:layout_height="match_parent" android:background="@drawable/back1" android:paddingBottom="@dimen/activity_vertical_margin" android:paddingLeft="@dimen/activity_horizontal_margin" android:paddingRight="@dimen/activity_horizontal_margin" android:paddingTop="@dimen/activity_vertical_margin" tools:context=".MainActivity" > <LinearLayout android:id="@+id/linearLayout1" android:layout_width="wrap_content" android:layout_height="55dp" android:layout_alignParentLeft="true" android:layout_alignParentRight="true" android:layout_alignParentTop="true" android:layout_marginTop="20dp" android:background="@drawable/red"> <Spinner android:id="@+id/spinner1" android:layout_width="match_parent" android:layout_height="match_parent" android:dropDownWidth="fill_parent" /> </LinearLayout> <EditText android:id="@+id/editText1" android:layout_width="wrap_content" android:layout_height="55dp" android:layout_alignLeft="@+id/linearLayout1" android:layout_alignRight="@+id/linearLayout1" android:layout_below="@+id/linearLayout1" android:layout_marginTop="25dp" android:background="@drawable/red" android:ems="10" android:hint="enter card number" > <requestFocus /> </EditText> <LinearLayout android:id="@+id/linearLayout2" android:layout_width="wrap_content" android:layout_height="55dp" android:layout_alignLeft="@+id/editText1" android:layout_alignRight="@+id/editText1" android:layout_below="@+id/editText1" android:layout_marginTop="33dp" android:orientation="horizontal" android:background="@drawable/red"> <Spinner android:id="@+id/spinner3" android:layout_width="72dp" android:layout_height="wrap_content" /> <Spinner android:id="@+id/spinner2" android:layout_width="72dp" android:layout_height="wrap_content" /> <EditText android:id="@+id/editText2" android:layout_width="22dp" android:layout_height="match_parent" android:layout_weight="0.18" android:ems="10" android:hint="enter cvv" /> </LinearLayout> <LinearLayout android:id="@+id/linearLayout3" android:layout_width="wrap_content" android:layout_height="55dp" android:layout_alignParentLeft="true" android:layout_alignRight="@+id/linearLayout2" android:layout_below="@+id/linearLayout2" android:layout_marginTop="26dp" android:orientation="vertical" android:background="@drawable/red" > </LinearLayout> <Spinner android:id="@+id/spinner4" android:layout_width="15dp" android:layout_height="18dp" android:layout_alignBottom="@+id/linearLayout3" android:layout_alignLeft="@+id/linearLayout3" android:layout_alignRight="@+id/linearLayout3" android:layout_alignTop="@+id/linearLayout3" /> <Button android:id="@+id/button1" android:layout_width="wrap_content" android:layout_height="wrap_content" android:layout_alignParentLeft="true" android:layout_alignParentRight="true" android:layout_below="@+id/linearLayout3" android:layout_marginTop="18dp" android:text="Add Amount" android:background="@drawable/buttonsty"/> </RelativeLayout> ```