Code working on emulator but not on real android phone

The following activity launches well in my emulator but shows an error message wen I try and launch it on a real android phone.I dont know what the problem is. I dont know how i can get the coz the error is in the phone. Here is the code:

package com.messageHider;

import java.util.ArrayList;

import android.app.Activity;
import android.content.Intent;
import android.content.SharedPreferences;
import android.database.Cursor;
import android.net.Uri;
import android.os.Bundle;
import android.provider.ContactsContract;
import android.telephony.PhoneNumberUtils;
import android.view.Menu;
import android.view.MenuInflater;
import android.view.MenuItem;
import android.view.View;
import android.widget.AdapterView;
import android.widget.AdapterView.OnItemClickListener;
import android.widget.ArrayAdapter;
import android.widget.Button;
import android.widget.ListView;
import android.widget.SimpleCursorAdapter;
import android.widget.TextView;
import android.widget.Toast;

public class sms extends Activity implements OnItemClickListener
{
    ListView listViewSMS;
    Button addMenuItem;
    Uri smsUri=Uri.parse("content://sms");
    Uri contactUri=ContactsContract.Contacts.CONTENT_URI;
    Uri phoneUri=ContactsContract.CommonDataKinds.Phone.CONTENT_URI;
    Cursor cursor;
    SimpleCursorAdapter adapter;
    public String menu_name;
    private SharedPreferences prefs;
    public static final String PREFERENCE_FILE="prefs";
    public long sms_id;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.sms);
        listViewSMS=(ListView)findViewById(R.id.listViewsms);
        listViewSMS.setOnItemClickListener(this);
    }
    @Override
    protected void onStart() {
        super.onStart();
        getsms();
    }
    private void getsms()
    {
        int count=cursor.getCount();
        String[]sender_number=new String[count];
        String[]sender_names=new String[count];
        String[]contact_id=new String[count];
        int counter=0;
        while(cursor.moveToNext())
        {
            sender_number[counter]=cursor.getString(cursor.getColumnIndex("address"));
            counter++;
        }
        int mycounter=0;
        for(int x=0;x<sender_number.length;x++)
        {
            Cursor mycursor=getContentResolver().query(phoneUri,null,ContactsContract.CommonDataKinds.Phone.NUMBER+"=?" ,new String[]{PhoneNumberUtils.formatNumber(sender_number[x])}, null);
            while(mycursor.moveToNext())
            {
                contact_id[mycounter]=mycursor.getString(mycursor.getColumnIndex(ContactsContract.CommonDataKinds.Phone.CONTACT_ID));
                mycounter++;
            }
        }
        int names_counter=0;
        for(int i=0;i<contact_id.length;i++)
        {
            if(contact_id[i]!=null)
            {
            Cursor cursor_names=getContentResolver().query(contactUri, null, ContactsContract.Contacts._ID+"=?", new String[]{contact_id[i]}, null);
            while(cursor_names.moveToNext())
            {
                sender_names[names_counter]=cursor_names.getString(cursor_names.getColumnIndex(ContactsContract.Contacts.DISPLAY_NAME));
                names_counter++;
            }
            }
        }
        //Populate the list with the array content
        ArrayList<String>arrayList=new ArrayList<String>();
        for(int j=0;j<sender_names.length;j++)
        {
            if(!arrayList.contains(sender_names[j]))
            {
                arrayList.add(sender_names[j]);
            }
        }
        ArrayAdapter<String> sendersArrayAdapter=new ArrayAdapter<String>(getApplicationContext(),android.R.layout.simple_list_item_1,arrayList);
        listViewSMS.setAdapter(sendersArrayAdapter);
    }
    @Override
    public void onItemClick(AdapterView<?> arg0, View v, int position, long id) {
        String sender=((TextView)v).getText().toString();
        Toast.makeText(getApplicationContext(),sender,Toast.LENGTH_LONG).show();
        prefs=getSharedPreferences(PREFERENCE_FILE, 0);
        SharedPreferences.Editor editor=prefs.edit();
        editor.putString("smsid", String.valueOf(id));
        editor.putString("smssender", sender);
        editor.commit();
        Intent intent=new Intent(sms.this,contactsmses.class);
        intent.putExtra("sender",sender);
        startActivity(intent);
    }
    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        MenuInflater inflator=getMenuInflater();
        inflator.inflate(R.menu.smsmenu, menu);
        return super.onCreateOptionsMenu(menu);
    }
    @Override
    public boolean onOptionsItemSelected(MenuItem item) {
        switch(item.getItemId())
        {
        case R.id.itemAutoHide:
            startActivity(new Intent(sms.this,autohide.c开发者_运维技巧lass));
            break;
        case R.id.itemHiddenMessages:
            startActivity(new Intent(sms.this,hiddenMessages.class));
            break;
        }
        return super.onOptionsItemSelected(item);
    }

}

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You are not initialising cursor before you start using it at the beginning of getsms(), and this will throw a NullPointerException.

I would be extremely surprised if this was working in the emulator.